@@TheDigitalMermaid I'm starting my second battery build 560 ah 24 volt from eve 280k cells grade a with the 2 hole welded terminal. I think I'm gonna use home made buss bars to link the cells. The flexible buss bars are great for links between cells in series but I'm making my own to link 2 cells in parallel then doing the series with the supplied flexible ones that came with the cells. I wonder if the 5 amp active balancers can be ran with the jk bms that has the 2 amp balancers or if I might not even need extra balancers? Any advice would be greatly appreciated
@@matthewknight5641 I've not played with external active balancers, but for the most part, you can ignore that cells in parallel are separate, and treat them like a single cell from a balancing perspective. The cells in parallel will balance amongst themselves, and if that means the group goes lower on average, they'll get charged up just the same, it'll just take longer.
Hi, cool videos ;-) A remark to the starting procedure of the JK BMS: I used the version for 8S-Systems and I found out that there is a simple way to start the BMS. Take a digital multimeter and switch it to Diode Test mode. Then contact the P- and B- with the test pins (minus to P- and plus to B-). The measurement voltage of the multimeter is enough to start the BMS! Hopefully this works also with the 20S version. Merry Christmas!
Really enjoying all the iterative build, test, change repeat. Just got Electrodacus BMS in the mail. I think I am going to really like this approach to BMS, where the BMS tells Multi and MPPT to quit charging or quit drawing instead of just shutting the battery off.
I'm hoping to create a bridge between the JK and the Victron gear, got a USB to RS-485 adapter on order. Any part being great in isolation has limited value.
@@TheDigitalMermaid I do that with a Raspberry Pi. The Pi acts as the main control unit for all the other stuff. It can control the charge controller, inverter, etc. and also can control e.g. diversion of excess power to the hot water tank when the battery is full.
Uh Oh... looks like JK is taking over. You're spot on with JK being a bit quirky, I've had it running for almost 3 weeks and I get occasional blank screens like you do. I've found closing the app (force close), and turning the BT off-on seems to make it happy again. The readout is not as easy to see at-a-glance as a lot of the others with a dial or bigger numbers, but that's well and truly offset by how well it works. I swapped from a Daly and this JK is much more accurate. The downside is readability, and current capacity. For me I'll be doing a 3P or 4P 16S system, and I know my 8kW inverter will draw 180A at times, so I'm close to the limit for a 200A BMS. If JK brings out a 12v 250A BMS, they will capture a massive market. Very methodical measurements tactics for the bus bars too. Not many people have that much attention to detail, you can use those skills in so many industries so keep it up. Thanks again for a very informative video!
There are (or at least used to be) 300A and 400A version with MOSFETS but they're hard to find. A 600A version (with relays) is available as well. By the way, did you find those MG Chemicals test results I did?
I had tried force killing without much luck. I didn't try cycling Bluetooth though. I also agree on the readout... It feels more stylish over function. Being able to pull 150A at 48v is really nice, and the balancing is fantastic. Quality and reliability though, the Overkill solar seems more reliable and easier to use. I'm torn. I think JK needs to step up their software to earn better marked share. If Overkill comes out with an active balancer version... Thanks again for the kind words. :)
@@TheDigitalMermaid Personally I prefer the JK software to the Overkill. You get instant feedback on settings you change (no load/store all settings at once), for example. The fact that the BMS can shut itself off to prevent further draining a battery that is low is awesome. All the little things, and the BMS wire resistance, etc in the software are in my opinion also better.
I enjoyed your battery re-assembly - and looking forward to see many more :) DigMer, I wish you the best for your holidays. Get rest, relax, meditate, get fresh air, meet with your family and friends. And please keep healthy. We await you on your channel to come back. See You!
Bolt down just one end to get the connection resistance. Post to near hole includes the contact resistance on one end. That minus hole to hole is the contact resistance.
For labels, lots of them will eventually fall of in my experience. (Glue just dissolves). I now have a Dymo labelwriter and use heatshrink, the dymo offers printable heatshrink. Love it!
I'm using the "extra adhesive" labels, same as I've used for about 15 years in my day job in IT. I've got the very first test label I put on the printer's power cable and it's still stuck as good as the day I put it on. I've had them sit in the hot-aisle of server racks for almost 10 years on ethernet, power cables and on the metal chassis without any failures. So I'm pretty confident in these.
@@TheDigitalMermaid Diesel is a miracle at removing things you don't want removed that uses glue, so ask a friend for a drip of diesel and dip one in that and let sit, this being said, that should be no issue for the battery as it should never see any!
A simple multimeter based resistance value should only be used in determining a fault in the system, not a rule or an constant of the overall system. There exist analytical testers, but those are complex instruments, used only in research labs, and those are very expensive stations and need special training and experience. The correct way to determine the overall DC resistance between two terminal posts is I-U method(voltage drop with known current). The method is simple and gives a lot of information not only about the performance of the bridge (bridge is the correct name, not bus bar/wire), but even overall performance of the whole battery assembly, and can be done with standard equipment. To measure the voltage drop, we need to introduce a known load current to the system and measure the voltage drop between the battery terminals( correct measurement location is batteries terminal itself, not the bolt/bolt head/etc.). For a known active resistance load we can use automotive halogen bulbs 24V 100W or even 200W connected in series-paralel. Those bulbs can safely operate to 29V DC, two in series =58V. Connecting those series strings to parallel we can have a step-by-step variable active resistance load and its cheaper than building a power resistor bank of expensive high power resistors, which would need a more expensive and bulky heat sink. For cooling those halogen bulbs we can use an inexpensive large PC cooler (in my experiments, below 80V DC, I drown the bulbs in a 12l plastic bucket of distilled water). To determine the current, we should use a calibrated DC current clamp or DC current transformer with calibrated voltmeter, not a shunt. A shunt will introduce an active series resistance to our system and could introduce an error of measurement to our overall battery assemblies performance. Using an inverter for load is not recommended bcs of the HF noise and non linear load it introduces to the overall battery assembly. The amount of tests performed should be at least 3 low current and atleast one high current equal or slightly exceeding the maximum current draw of the systems design. The first 3 tests (lets say 10A, 25A and 75A) we measure and record the voltage drop between the bridged terminal posts and the load current at the same time; so on with all the bridges of the battery. The measurements should take place after abut one minute of the load introduction to the system to let the temperature and so called "current shock" to stabilize(electrochemical processes are complex and batteries have ionistor/supercapacitor effect also). The last test, or so called the maximum load current(I recommend +10% of the designs max load current level), should be carried out after about 10 minutes of introduction of the load. That test will show us the worst case temperature rise of the connections aswell(use a dedicated IR thermometer on the bridges and terminal bolts/posts, do not trust uncalibrated IR cameras on some sort of a phone; using siedbeck effect thermal sensors is not advisable bcs of the hall effect near high intensity magnetic field). The 10 minute time is not a law, it only a ballpark, and is determined of the thermal mass of the system itself(the longer, the better). This test will give us the information of the worst situation possible of that particular system: the temperature rise, internal resistance rise of the whole pack, efficiency drop, etc. My recommendation is to draw graphs to paper or PC and You will have a visual representation of Your work and it will give hints for improvements. Once You have the "picture" in Your mind, You will have much less of a hassle to engineer and build the next one. The main problem in marine type of electrical systems(not only electrical, but all the mechanical/physical contacts between two different metals) is electrochemical corrosion. There are different ways to rectify the problem(elimination is impossible) and the simplest way is to use the same metals of contact. Stainless steel has limited chemical resistance, zero electrochemical(have seen the bolts used for connection of the batteries?). There is a lot of mumbo-jumbo of stainless steel bolts and nuts used in battery terminals, and even in marine conditions, but its all wrong. The problem is that most Li based large batteries use aluminium terminals(not only in ion battery systems, but all battery chemistries); its chemically active material. Yes, it summons a protective layer of oxide in contact with oxygen, but its not resistant to electrochemical corrosion when introduced with different metal surface contact with the presence of an ionic/acidic/etc. fluid/salt; aluminium will rot away in most cases(basic chemistry, remember the line of active-passive metals). For stationary battery installations, even stainless steel is not recommended bcs of the high electrical resistance; use bronze or messing bolts/nuts. Pure copper is also not recommended even in stationary installations with contact of aluminium. My recommendation is to use aluminium U shaped bridges between the battery posts and aluminium bolts(duraluminium/aviation aluminium/ etc.). They are expensive, but its a lifetime warranty. If there is no way of getting those, use bronze(heavy nickel plating is also acceptable) and after the tightening/full testing, coat the terminals and bridges with petroleum jelly, silicone fat(not silicone oil!) or V-66 aerosol compound(used in PCB prototyping, use 6 layers atleast). I recommend the use of V-66 PCB varnish, bcs its not that messy and is resistant to chemical/temperature/static discharge/ etc. attacks. It can be removed with slightly abrasive plastic sponge(the same used to clean dishes). Those coatings will not let the corrosion allowable media to come into contact/between the different metals. Surface area and current density are the fundamental constants in determining the battery assemblies performance, and the efficiency of transmission to the load. The tables on the the internet are actually useless. They are a guide of max temperature rise of a particular wire and isolation performance according to current and installation method. In battery installations, especially low voltage/high current, we need to know the max allowable voltage drop between the source and load; it determines the efficiency of overall system. Example: 1mm^2 copper can withstand 1kA(temp rise can be about 800C, isolation will fail, conductor stays), but that size is an inefficient conductor for a battery installation; voltage drop squared=power dissipation. The right question here is, how much do we allow to lose? Aluminium has about 2x less electrical conductivity per sqr-mm, but its an ideal conductor to make contacts between the batteries aluminium terminals(near 0 electrochemical corrosion). Problem here is: where to get aluminium bridges that are mechanically soft (woven belt like conductor with aluminium terminals). BMS and the right place of balance/measuring wire is also dependent of the current draw/voltage drop between the batteries bridge terminals. To minimize the voltage error(adds to voltage drop of the bridge between batteries and its temperature dependent) the right place of single series connected battery assemblies BMS wire connection is the midpoint of the bridge. That way we ensure, that the voltage drop is symmetrical between two series batteries, and its absolute value is independent of the overall load current(charging and discharging of the battery represent a load to the bridge connector, only the current way changes not the voltage drop polarity). Too much information for the first time. Next time I will introduce You to the secret world of electrochemical isolation and hydro isolation of marine installations. Maybe will type some musings of electric drives also... If You, and the respected public, are interested.
for marine purposes you have to solder all wires. In the long run humidity shall corrode connections. Been boating for more the 40 years. Had my portion of corroded bad connection LOL
the important thing is to calculate the voltage drops .. singularly and end to end .. then consider whether it is SIGNIFICANT .. there are always variations as you know .. the aim is to be better than the spec ... a few calculations loaded in excel and you have it ... if it is in the ok range .. then you can determine the physical attributes as to length and stresses on terminals .. how it affects your long term mechanical stress on the terrminals /batteries .. smiles .. which i agree with you .. critical over time in moving dynamic environment .. you are doing excellent work .. i have found over many years of computing it is more relevant to ensure imaCULATE connection/contact resistance by using no-oxide A or similar to seal the joint from atmospheric attack and verdigree build up.. MEANS LESS MAINTENANCE OVER TIME TO TRACK .. opps .. erroneous problems in a stacked and loaded system.. hopefully none.. but reality is always MURPHY comes to town ...lol... merry xmass and happy new year to u and urs !
Power supplies/batteries create or are a voltage difference. Just add a 5V power supply in series to the battery. Attach the negative of a 5V power supply to the positive of the battery, then there should be (battery-voltage + 5V) between the negative of the battery and the positive of the power supply. It's the exact same thing that you are doing by putting your battery cells in series. Iirc, Andy also seemed to be wanting to use a powersupply to create the full voltage to boot the bms. Even a simple usb power bank will do just fine.
Resistance in any conductor is directly proportional to the length. If you want to lower it at a specific needed length you need higher GA or put more in parallel. To see how much the resistance of the wires influences things, you need to know the internal resistance of the batteries. Then you can see if that % is significant or irrelevant.
You can also boot the JK with a 9V battery. The Bluetooth range is limited because the module sits in a metal enclosure. You could actually put an external antenna on it, but it requires you to take the thing apart.
Can also write it here that Andy uploaded one of the manuals for the JK-BMS under the BMS section, that also show how to do it. There is also another YTvideo that show this I linked to under the Andys JK-BMS-video comments.
I thought it was as simple as putting a 9V battery in your enclosure, adding a momentary switch and putting the pos and neg across the P- and B- on the BMS? All it requires is a voltage greater than 5V. A 9V battery is cheap, small and easy to replace than needing a dedicated workshop powersupply or using your generator on the boat just for a >5V jump.
Probably not relevant today but love your enthusiasm.. Very interesting that you are paying attention to the cell to cell resistance. I'm a person of simplicity and would like to say; I wouldn't pay much mind to the resistance values from that meter. Verifying the resistance of the buss bar over your home made paralleled 10AWG jumper you should be measuring at micro ohms with at least a 3 amp to 10 amp current signal calibrated to conductor temperature. lets agree that's really not necessary for this build however nice. Unless you are building to sell and you are trying to pinch pennies for production. The 3 points that matter as you build your battery. #1 resistance needs to be low at each cell connection, #2 resistance needs to be low in the connector from cell to cell. #3 the connector needs to be flexible for expansion and contraction of cells during transportation, heating - cooling from charge discharge cycles. Address #1 make sure the cell post contact area is flat and smooth, clean, and big. You can only ensure you clean the post and use as much of the post you can with your cell to cell jumper lugs. Address #2 from what I see of what you built, the 1'st option is perfect as long as you are allowing for 125% max current the lugs you are using have what looks like adequate surface area. Address #3 the short size of the 1st jump which has enough elasticity required, as nice as that 2nd loop jumper is you don't need to over build as in that example. What I mean is different length #10 cables and a big loop adds more that can go wrong than right. Finally need to be sure you clean the lug and use stainless hardware with a beveled washer pointed correctly, and torque each and every bolt as specified by the battery manufacture mark each connection after you torque it. PS. use de-natured alcohol for cleaning connection points avoid using greenies you want smooth surfaces to contact each other. and please put some venting in that wooden box top and bottom...
On the victron check that you have a tail current of something low (like 0.1amps). It will then stay in absorption longer to slower more filling the battery at the top end when charge suddenly drops off. Maybe I’m wrong about this but helps me on my MPPT. I’m pretty sure the multi and Quattro have similar settings.
Have 1/16" thick aluminum busbars made. The ones I made IIRC were 1.5" or 2" wide. Because they are thin the flex if required to make good contact with the terminal end. I have a few spare I can send you if you want to test them.
Very kind of you to offer. I think I'm settled on the shorter 4x 10awg though. A big reason being that I can make them as I need them, even later when on the boat. You might want to check with one of the other, more testing focused, channels though. Cheers
There’s many ways to figure out bus bar/wire resistance and the losses on your LifePo4 banks. You can measure the mV voltage drop while under load and even figure out the Watts lost in each connection. You can measure the width x thickness like 2mm x 20mm and use online charts to show the resistance per inch of foot. You can use a thermal camera and under load you can see the connection quality and losses for each connection and the entire battery at once to spot all the high loss spots you need to correct. You can also check a few types of bus bars at the same time with a thermal camera. You could heads up compare a solid copper bus bar, the flexible 10 AWGx4 and 4 AWG while under load and you will see all the problem connections stand out instantly. Also check wire charts as true Gauge properly made pure copper 10 AWGx4 and 4 AWG have almost exactly the same resistance per foot. The millivolt drop with a set load in Amps will allow you to calculate the resistance without a milli ohm meter and show you how many watts are lost at that junction. Does your fuse drop 40mV when under a 100 Amp load? So is your fuse wasting 4 Watts and how many kWh’s will be lost over time? How about your switch? You can even figure out the losses in your BMS by the voltage drop on a load. You can even figure out the total losses and efficiency of your battery as a whole. Is only 80% of the kWh’s going to the motor or 98%? You can measure the voltage drop under load and know. Also there’s also pre-made copper "braided" “flexible” busbars. By using 4AWG busbars instead of 1/0 or 4/0 are the total losses of all connections on all 6 battery banks at 100Amps causing you to lose the 20% of energy of an entire battery bank or just 1%? You should know as 20% would be like having 4.8 battery banks not 6. I’m just trying to get you to calculate the total losses NOW and it should have been done before you started as you might find cutting 1 pound off of bus bar wire might be like losing 2, 5 or 20 or 50 pounds of battery capacity and battery cost and charging losses and boat loading and motor efficiency due to added drag. Also what will be the bus bar battery losses at 10%, 50% and 100% throttle? Using 4AWG or 1/0 or 4/0 AWG bus bars. It’s pretty easy to figure out. Personally I would have a FLIR thermal camera with me at all times as there are 100’s of problems and uses for it inside a boat and a laser thermometer gun. You can quickly spot a crimp or terminal failing on all your battery banks at once. Using an ohm meter on 100’s of terminals takes forever and is hard work on a boat in the water. Even when you’re done you won’t know what side of the terminal or crimp is the problem like you can with a Flir Thermal Camera. Even the phone Thermal camera’s like a $200-300 FLIR one or FLIR one Pro are plenty good for this. You can spot hull delamintion and weak pipes, bad insulation, water leaks and intrusion and endless other stuff like hot spots on solar cells and bad wiring!@! all over your boat. Google and look at a bunch of FLIR thermal images of Marine Surveys and hull delamination.
I was thinking about making busbars from 2/0 cable, short as possible, using welder cable, for a peak of 250 amps, I was hoping resistance would be low, and still be flexible!
You should try making some flex bus "bars" with multiple thin flat stock. I bought some but they haven't come yet, to see how they are made. But i think it is just multiple thin flat stock.
@@TheDigitalMermaid that is true. wish I had thought of that before ordering 7. they ain't giving those away. lol. On my last two 8s 105Ah, packs I built, I made my own but they were so short, they really didn't have much give. I think I'm going to do those two packs over with these curly bus bars. they kinda look cool too. have you tried the braided type used for grounding in vehicles?
@@immrnoidall I haven't, but Andy did, and I can't say he was impressed. He tested them at the same time as he tested the two types of "flexible bus bars" I made. The ones I chose to build for my boat are the 4x 10awg ones, as they give the best flexibility in all axis of movement. th-cam.com/video/EjBqng70ORc/w-d-xo.html
@@TheDigitalMermaid blue tooth slowly died and finaly stopped working. uninstalled the app to reinstall and nope. will not install . installed a bunch of other stuff on the phone fine . not this JK bms from hell. and no support from seller or anyone. TRASH.
if you look on the back of the plug you find a strip gauge also if this is for the boat you said it was for your shore power. Shore power will be a 30 amp 120 volt twist lock ore are talking about pluging into the 120 volt outlet in your boat
There was a video i watched where someone used one extra battery somehow with their pack to start the bms up (like a 6v or 9v). i got a jk bms and plan to be without mains but it has the extra screen and button and the renogy rover charge controller has a lithium wake up function provided there's sun. i hope you work out a good solution
Couldn't you use a simple double pole switch with a 5v+ reduction resistor to momentarily connect a drop in battery voltage to trigger it to start? Also I'm curious how my battery busbars would perform vs your flexible. I used copper pipe that I flattened into busbars and drilled holes in each end, but for relief as I was worried about expansion, I made the DIY copper busbars 1 inch longer than needed and bent a small 1 inch wide V in the middle, which gives the busbar the ability to expand with the batteries if its ever an issue, since the busbar is able to move pretty easily with that V bend in the middle a slight amount.
If you have the movement problem, why don't you fix the batteries together then? You will even get a bonus with more cycles to then? (First time watching the first video from you) cheers from 🇧🇻
To turn on the JK BMS. Just buy their LCD... It has a power Button. And the added bonus of a visual status of the Battery (Voltage, capacity, current).
One problem with the "LithiumSolar loop" idea is that each loop has more inductance than a straight-ish wire. This higher inductance will cause trouble during load transitions in your power system, such as when turning on or off a large motor, which is yet another reason for you to return to your original flexible bus bar idea.
You were stressing over not having a 5v battery but the requirement is greater than 4v so you can use (3) AAA in series or a 9v battery which is a much simpler method. JK also now offers a display that has a built-in on/off button.
0.19 mOhm loop busbar have inductance and its not accurate to measure it like this. I suggest to make Voltage drop in ohms law.. but flat metal busbar is the best. i am making aluminum bubars for my cells with length of 14 cm and resistance 0.074 mOhm
How do I make a 64S BMS if I only have 4pcs of 16S BMS? Do I make 4units of 16S batteries, then connect all these 16S batteries in series (of course only through the BMS)?
A 64s pack would be 204.8v, I'm guessing that's not what you actually want, is it? If you mean to run all 64 cells off one 16S BMS, then you could create 16 separate 4p packs (connect the positive of four cells together, and their negatives together) to create a single 3.2v cells with 4x the amperage, then connect those 16x 4p sub packs in series. This would give you a 16s4p config at 48v.
@@TheDigitalMermaid Actually, yes I want to make high voltage battery bank using just 16S BMSs. I am thinking it would eventually fail because they wont balance each other. Why High voltage? Some inverters use high voltage to reduce current draw and heat on the batteries.
Given the cells are quite "snug" within the box (I forget if you bound the cell blocks with fibretape or something else) it is "So Unlikely" that the cells will ever expand or contract to any noticeable point. They will ONLY swell is you over charge at a Hi C-Rate or Over Voltage which is not likely with the system being setup properly. I've read & seen vid's by Marine Folk and most of them use the standard busbars. The fixation on flexible to this extent honestly seems too overkill. The JK will also show you what it sees for resistance per cell, will be interesting to see you compare those readings with the TR-1035 tester. One you do that, "Just for Fun" then replace one of your "fancy flexies" with a solid bar and see what the JK & TR say in comparison. Might be interesting. BMS -B -P wires are AWG-7. 2x7-AWG = 4-AWG. One Option to extend wires, you can use a 4-AWG Barrel Connector and extend with a single 4AWG wire to Lug. BMS Sense Leads are 22-AWG 22 AWG x2 (folded over as done in this vid) = 19 gaugue effectively. Excellent Wire Gauge calculators here: www.wirebarn.com/Combined-Wire-Gauge-Calculator_ep_42.html
Keep in mind, "marine use" is a very broad classification. If I only planned coastal cruising and the loss of power meant I lost my fridge, i'd agree that I am obsessing too much. In my case, I will live on the boat and I will be doing crossings. I will be sailing in bad weather and pounding seas. The shock loads will be fairly frequent and strong, relatively speaking. Also, my batteries are my house bank and my fuel tank. The loss of power, or worse, over heating from a loose terminal when I'm off shore, have significant consequences for me. In this light, I don't think it's unwarranted obsession.
Think each bus bar as small resistor. That includes ring terminal. In series resistance increases, in parallel it gets half. Ring terminals are always weak spot. Because unlike wire that has lots of strands to carry current. Ring terminals don't have the same amount surface area. Try 2 two wire ones in parallel might be better than one 4 wire one.
Also 10AVG silicone wires have difference. Most chinese wires have 1050 strands of 0.08 wires. When i got my self 8ne with 1946 strands of 0.06 wire. Core does not matter only surface area of the wire.
Hi Digital Mermaid, new subscriber to Andy's channel which sent me your way by his recomendation. (Yes, new sub for you :)) You've gone to the detail of checking internal resitances and logging for each battery, terminal.... and derived the relationship of resistance with diameter and length, does your BMS allow for different resistance values across each of your balance leads? If they are different lengths or trimmed down to reduce excess and have a neater install, would there not be a difference in behaviour from the BMS charging a cell with the shortest balance lead vs longest due to the reistance of the balance lead itself? Keep up the good work and learning!!!
Would it not be more practical to protect the battery box from vibrations then going down the rabbit hole and protect every connection? example put the battery box on rubber feet of sorts?
I will try of course, but the weight of the battery boxes and how hard you can get pounded on the sea, it's impossible to prevent shock and vibration from going through.
@@TheDigitalMermaid I saw another youtuber who also is building a battery pack with the same type of cells and he used flexible bussbars, kind of a copper laminated busbar. maybe an option?
@@nordexo That was LithiumSolar! I chatted with his as I did my first flexible bus bars at the same time he made that video. He's the one who gave me the loop idea.
You connected the BMS wiring before you connected them to the battery after you crimped the connectors on. So if you did make a short. You harmed the battery AND the BMS.
Energy will flow trough the lowest resistance. This might overheat your flexible bus'bar'. Your battery should NOT be able to move, so you do not need flexible busbars. When you use cells that allow movement, the friction between the cell might create a short.
So the cable resistance is twice the cell internal resistance ... you're going to be losing more power in the links than in the cells. Wire sizing is partly about heat (melting the wires is bad!) but mostly about power losses. With 16 cells at 0.03mO for the solid links vs .15mO for the wire and 0.07mO for the cells you've got power losses of I2R, so at 5kW = 100A draw on the pack you'd be losing 11W in the cells, 5W in the solid bus bars or 24W in the wires. Which isn't really significant, saving 20W on a 5kW load when you're losing that much in the battery monitoring system or inverter isn't really critical. IMO anyway. I'd be more concerned about the solid bus bars not aligning perfectly with the terminals and giving you unexpectedly high resistance there. FWIW you might be better bolting the links in place then measuring from bolt to bolt on the batteries would be more useful.
@@TheDigitalMermaid Thanks you, since we connected both end of battery with charging system via bms and individual we connected each battery with wire to read and balance, here Question How we stop ✋battery from charging while next battery still charging via bms I'm still not clear about way of charging?
I actually don't understand why anyone would think a wire would transfer electricity better than a copper busbar. That would never have entered my mind. Maybe try reading conductivity instead of resistance or something else. (better meter)? IDK
You know that 0.03mOhm at 100A is only 3mV drop. 4 series means a total of 12mV dropped in the bus bars for a total of 12mV*100A = 1.2 watts. In the grand scheme of things, that's sod all squared given it would be a 1.2W drop on a 4800W circuit! Surely you have bigger ghosts to hunt? The only concern with bus bar drop would be the error factor in the cell voltages being out by up to 12mV could effect balancing and cell monitoring and tiny, tiny, tiny little bit. Surely nobody runs their tolerances that close.
Should point out the current shunt in the BMS will probably drop 10 times that voltage. You could remove it and just measure the drop across a bus bar. It will be very hard as it only drop 12mV at 100A. The BMS's shunts will be more like 0.1 or 0.05 and drop more like 2 or 3 watts just measuring the current.
Well, I mean, ya of course. Two points; First is covered in the very first video, "I'm new to this". Second, I knew before that there was a difference, but the amount of difference was unexpected.
@@teddypreston5525 Possibly, but I try to give everyone the benefit of the doubt and give genuine answers. If not for the person asking the questions, then for people who might find the conversation in the future.
@@TheDigitalMermaid I’m still waiting on laminated buss bars and have not powered up my JK BMS. Can you tell if they do soft start when turning on? Maybe a pwm duty cycle for a second or two?
@@ai4px I'm not sure what you mean by "soft start". I think of inverter and motor study starts, but I'm guessing that's not what you mean. The BMS beeps, and starts supporting power. I've not connected a load and plotted amperage.
@@TheDigitalMermaid I’ve used the chargery DCC module and when it turns on it does an increasing pwm duty cycle for the first second or so. Saves spikes caused by inverter caps. But…. It is an idiotic design because the DCC soft start only happens when you manually flip the power switch and never from the remote on/off connector. I blew mine up after two or three iterations. Now I used a pre charge resistor across a gigavac contactor.
As I said under previous video, you are still way too much complicating things. Compress the battery with sheets between them -> ignore vibrations and dilatation. Use rigid bus bars. Simplest, cheapest, most effective. You are inventing dead ends which is fine if you want to play with it, I just hope other ppl wont try to copy it.
I've explained my reasoning throughout the build. If you think something in my logic is wrong, cool, explain why. I've changed a lot of my designs thanks to productive feedback. Simply being told that I'm wrong isn't very convincing though.
@@TheDigitalMermaid First part was in my post under fancy layout video. Instead of 15 short and one long cable, you got 16 medium long cables. Design that was more difficult to make, required a map to figure out battery order and put high different potentials close together so accidental shorts would cause more sever damage. You try to improve things. Trying to make it better is fun, but thousands of ppl already tried that, we don't need to reinvent hexagonal wheels. There are engineering codes and recommendations and one of those is keep it stupid simple, because it will be more robust. You can easily repair/replace things and you will understand the design years later without a map. If long positive/negative cable heats too much, you can use thicker cable or even copper bar, no need for overcomplicating things. Most manufacturers nowadays already recommend compressing the battery, because it will give you 30-40 % more life cycles which I think is pretty significant. It's in the battery's datasheet, manufacturer knows why he put it there, yet you still prefer not to do it. You are afraid of vibrations and movement despite if you compress the battery with sheet separators, this would be non-issue and you can use copper bus bars. As you've measured it, they are superior to cables and you can use thicker ones that you've measured, lower losses and less prone to build errors (bad joint lug-cable). In engeneering less build steps is always better - faster and cheaper to make, more reliable, less space for errors and failures later. There are simple and verified solutions. Trying to outsmart everyone and make something better usually leads to worse results. If you do something differently than what everyone does and what is recommended, you should have pretty good reason, but I don't see any. What I see is that first deviance from "usual" leads to necessity to change other things and compensate for insufficiencies of the change. Yet that change is not needed in first place
@@MiH1IT One of the things a lot of manufactured solutions do is chase cost of manufacture. Stamping copper bar is a lot cheaper than making cable connectors, as an example. So the argument that manufacturers have come up with the ideal solutions is valid _if_ you accept that all projects have the same goals and focuses. To be clear, I do not think I am smarter than others. I have made this pretty clear since my very first video. What I am doing is explaining through these videos what _my_ focuses are, and trying to figure out what solution works best for me. The goal of this channel is not to be a recipe for others to follow. Its goal has been to show the process of learning and figuring out what works best for each person in their own projects. The idea that we shouldn't bother because we'll never be as good as the experts would be to argue that DIY is fatally flawed in principle. I think we'll have to agree to disagree on this.
@@TheDigitalMermaid I did not say that it was solution that manufacturers only use. In our (my country) solar diy community I see 90+ % bus bars, same if I check "solar lifepo4" in google photos and yt video thumbnails. When something is easier to make and works better it can still be cheaper. Just because it is cheaper or less complex, it does not make it worse. You use batteries that manufacturer said you should compress to get the best result, but you don't even trust the battery manufacturer.
@@MiH1IT The spec sheet doesn't say they should be compressed, only that the degradation of capacity to 80% of rated would change from 2500 to 3500 if compressed. As I explained in an earlier video, the batteries will age out before that difference matters to me in my use case. I'm not sure where this energy is coming from... I've explained my reasoning and rationale for doing the design I'm doing. It's up to anyone viewing my videos to decide for themselves if my logic makes sense to them or not.
a note on using specialty tools vs your desire to keep this to things that others can duplicate If you use specialty tools that people send you to evaluate different options and show the advantages/disadvantages of the different options, others don't need those tools to build their batteries or to take advantage of the testing that you do with the tools. Just avoid situations where you are using a speicalty/expensive tool for tuning things as opposed to the evaluation of different options like you did here.
Okay let's start again hello friend I watch lots of your videos I notice you located in Canada so me too perhaps you'll be kind and may be able to help I just bought JK BMS I am not able to download any the app I even try different phones I would appreciate so much has you know anything about this problem JK support do not answer any emails or text I hope you will be able to help we notice you have so many BMS thank you I'm sorry to bother you checking out John have a nice day
I dont think u r thinking logically or critically. To me the most sense to me is if its resistance u r trying to lower than get a solid copper bus bar the size that they shipped with the batteris and test it to the one they sent with the batteries. It dont matter if u r in a boat or an rv those batteries r not vibrating out of that box they r in nor r they moving around inside the box so why r u try to make the bus bars flexible? Please help me to understand.
DO NOT CHARGE THOSE BATTERIES TO 3.65 VOLTS per cell. You will shorten the life of those batteries. Charge to 3.60 max per cell. Your maximum pack voltage should be no more then 57.6 VOLTS. Also don’t let the pack go below 43 VOLTS and you should be fine and you should get about 3800 cycles and more out of them. Also keep those batteries inside at room temperature.
With do respect, the data on the data sheet is the source of truth on what is safe. They're are times you want to do a full charge, and a capacity test which I want to do, is one of them. The all-caps command to not so something leaves no space to assume the person you're taking to know what they're doing and has a reason for doing it.
Thought of another who if you have not watched his videos then I recommend you do it as he has tested a bit with internal resistance and on cables reminds a bit of your videos that some are long th-cam.com/video/tGmOFYDPHfQ/w-d-xo.html one of many videos and it is unnecessary for more people to test the same things to come to similar conclusions, but he is much more "careful" that everything should be the same
You, Andy, and a few other youtube people have taught me so much qbout building a battery and about the bms stuff. Thanks
Very happy to hear that, Matt! ^_^
@@TheDigitalMermaid I'm starting my second battery build 560 ah 24 volt from eve 280k cells grade a with the 2 hole welded terminal. I think I'm gonna use home made buss bars to link the cells. The flexible buss bars are great for links between cells in series but I'm making my own to link 2 cells in parallel then doing the series with the supplied flexible ones that came with the cells. I wonder if the 5 amp active balancers can be ran with the jk bms that has the 2 amp balancers or if I might not even need extra balancers? Any advice would be greatly appreciated
@@matthewknight5641 I've not played with external active balancers, but for the most part, you can ignore that cells in parallel are separate, and treat them like a single cell from a balancing perspective. The cells in parallel will balance amongst themselves, and if that means the group goes lower on average, they'll get charged up just the same, it'll just take longer.
@@TheDigitalMermaid awesome. Thankyou..
Hi, cool videos ;-)
A remark to the starting procedure of the JK BMS:
I used the version for 8S-Systems and I found out that there is a simple way to start the BMS. Take a digital multimeter and switch it to Diode Test mode. Then contact the P- and B- with the test pins (minus to P- and plus to B-). The measurement voltage of the multimeter is enough to start the BMS! Hopefully this works also with the 20S version.
Merry Christmas!
OK I wish I was hope to test this right now. I will absolutely test it when I get back!
Really enjoying all the iterative build, test, change repeat. Just got Electrodacus BMS in the mail. I think I am going to really like this approach to BMS, where the BMS tells Multi and MPPT to quit charging or quit drawing instead of just shutting the battery off.
I'm hoping to create a bridge between the JK and the Victron gear, got a USB to RS-485 adapter on order. Any part being great in isolation has limited value.
@@TheDigitalMermaid I do that with a Raspberry Pi. The Pi acts as the main control unit for all the other stuff. It can control the charge controller, inverter, etc. and also can control e.g. diversion of excess power to the hot water tank when the battery is full.
@@upnorthandpersonal do you have docs or guides for this?
@@TheDigitalMermaid Comment removed again... sent an email.
Uh Oh... looks like JK is taking over.
You're spot on with JK being a bit quirky, I've had it running for almost 3 weeks and I get occasional blank screens like you do. I've found closing the app (force close), and turning the BT off-on seems to make it happy again.
The readout is not as easy to see at-a-glance as a lot of the others with a dial or bigger numbers, but that's well and truly offset by how well it works. I swapped from a Daly and this JK is much more accurate. The downside is readability, and current capacity. For me I'll be doing a 3P or 4P 16S system, and I know my 8kW inverter will draw 180A at times, so I'm close to the limit for a 200A BMS.
If JK brings out a 12v 250A BMS, they will capture a massive market.
Very methodical measurements tactics for the bus bars too. Not many people have that much attention to detail, you can use those skills in so many industries so keep it up.
Thanks again for a very informative video!
There are (or at least used to be) 300A and 400A version with MOSFETS but they're hard to find. A 600A version (with relays) is available as well. By the way, did you find those MG Chemicals test results I did?
I had tried force killing without much luck. I didn't try cycling Bluetooth though. I also agree on the readout... It feels more stylish over function. Being able to pull 150A at 48v is really nice, and the balancing is fantastic.
Quality and reliability though, the Overkill solar seems more reliable and easier to use. I'm torn. I think JK needs to step up their software to earn better marked share. If Overkill comes out with an active balancer version...
Thanks again for the kind words. :)
@@TheDigitalMermaid Personally I prefer the JK software to the Overkill. You get instant feedback on settings you change (no load/store all settings at once), for example. The fact that the BMS can shut itself off to prevent further draining a battery that is low is awesome. All the little things, and the BMS wire resistance, etc in the software are in my opinion also better.
I enjoyed your battery re-assembly - and looking forward to see many more :)
DigMer, I wish you the best for your holidays. Get rest, relax, meditate, get fresh air, meet with your family and friends.
And please keep healthy. We await you on your channel to come back.
See You!
Thanks for putting this vid out before you left for holidays....You are giving us all the best Xmas present :)
Bolt down just one end to get the connection resistance. Post to near hole includes the contact resistance on one end. That minus hole to hole is the contact resistance.
Thanks for the video. Have a great Christmas and holiday.
For labels, lots of them will eventually fall of in my experience. (Glue just dissolves). I now have a Dymo labelwriter and use heatshrink, the dymo offers printable heatshrink. Love it!
I'm using the "extra adhesive" labels, same as I've used for about 15 years in my day job in IT. I've got the very first test label I put on the printer's power cable and it's still stuck as good as the day I put it on. I've had them sit in the hot-aisle of server racks for almost 10 years on ethernet, power cables and on the metal chassis without any failures. So I'm pretty confident in these.
@@TheDigitalMermaid Diesel is a miracle at removing things you don't want removed that uses glue, so ask a friend for a drip of diesel and dip one in that and let sit, this being said, that should be no issue for the battery as it should never see any!
A simple multimeter based resistance value should only be used in determining a fault in the system, not a rule or an constant of the overall system. There exist analytical testers, but those are complex instruments, used only in research labs, and those are very expensive stations and need special training and experience. The correct way to determine the overall DC resistance between two terminal posts is I-U method(voltage drop with known current). The method is simple and gives a lot of information not only about the performance of the bridge (bridge is the correct name, not bus bar/wire), but even overall performance of the whole battery assembly, and can be done with standard equipment. To measure the voltage drop, we need to introduce a known load current to the system and measure the voltage drop between the battery terminals( correct measurement location is batteries terminal itself, not the bolt/bolt head/etc.). For a known active resistance load we can use automotive halogen bulbs 24V 100W or even 200W connected in series-paralel. Those bulbs can safely operate to 29V DC, two in series =58V. Connecting those series strings to parallel we can have a step-by-step variable active resistance load and its cheaper than building a power resistor bank of expensive high power resistors, which would need a more expensive and bulky heat sink. For cooling those halogen bulbs we can use an inexpensive large PC cooler (in my experiments, below 80V DC, I drown the bulbs in a 12l plastic bucket of distilled water). To determine the current, we should use a calibrated DC current clamp or DC current transformer with calibrated voltmeter, not a shunt. A shunt will introduce an active series resistance to our system and could introduce an error of measurement to our overall battery assemblies performance. Using an inverter for load is not recommended bcs of the HF noise and non linear load it introduces to the overall battery assembly. The amount of tests performed should be at least 3 low current and atleast one high current equal or slightly exceeding the maximum current draw of the systems design. The first 3 tests (lets say 10A, 25A and 75A) we measure and record the voltage drop between the bridged terminal posts and the load current at the same time; so on with all the bridges of the battery. The measurements should take place after abut one minute of the load introduction to the system to let the temperature and so called "current shock" to stabilize(electrochemical processes are complex and batteries have ionistor/supercapacitor effect also). The last test, or so called the maximum load current(I recommend +10% of the designs max load current level), should be carried out after about 10 minutes of introduction of the load. That test will show us the worst case temperature rise of the connections aswell(use a dedicated IR thermometer on the bridges and terminal bolts/posts, do not trust uncalibrated IR cameras on some sort of a phone; using siedbeck effect thermal sensors is not advisable bcs of the hall effect near high intensity magnetic field). The 10 minute time is not a law, it only a ballpark, and is determined of the thermal mass of the system itself(the longer, the better). This test will give us the information of the worst situation possible of that particular system: the temperature rise, internal resistance rise of the whole pack, efficiency drop, etc. My recommendation is to draw graphs to paper or PC and You will have a visual representation of Your work and it will give hints for improvements. Once You have the "picture" in Your mind, You will have much less of a hassle to engineer and build the next one.
The main problem in marine type of electrical systems(not only electrical, but all the mechanical/physical contacts between two different metals) is electrochemical corrosion. There are different ways to rectify the problem(elimination is impossible) and the simplest way is to use the same metals of contact. Stainless steel has limited chemical resistance, zero electrochemical(have seen the bolts used for connection of the batteries?). There is a lot of mumbo-jumbo of stainless steel bolts and nuts used in battery terminals, and even in marine conditions, but its all wrong. The problem is that most Li based large batteries use aluminium terminals(not only in ion battery systems, but all battery chemistries); its chemically active material. Yes, it summons a protective layer of oxide in contact with oxygen, but its not resistant to electrochemical corrosion when introduced with different metal surface contact with the presence of an ionic/acidic/etc. fluid/salt; aluminium will rot away in most cases(basic chemistry, remember the line of active-passive metals). For stationary battery installations, even stainless steel is not recommended bcs of the high electrical resistance; use bronze or messing bolts/nuts. Pure copper is also not recommended even in stationary installations with contact of aluminium. My recommendation is to use aluminium U shaped bridges between the battery posts and aluminium bolts(duraluminium/aviation aluminium/ etc.). They are expensive, but its a lifetime warranty. If there is no way of getting those, use bronze(heavy nickel plating is also acceptable) and after the tightening/full testing, coat the terminals and bridges with petroleum jelly, silicone fat(not silicone oil!) or V-66 aerosol compound(used in PCB prototyping, use 6 layers atleast). I recommend the use of V-66 PCB varnish, bcs its not that messy and is resistant to chemical/temperature/static discharge/ etc. attacks. It can be removed with slightly abrasive plastic sponge(the same used to clean dishes). Those coatings will not let the corrosion allowable media to come into contact/between the different metals.
Surface area and current density are the fundamental constants in determining the battery assemblies performance, and the efficiency of transmission to the load. The tables on the the internet are actually useless. They are a guide of max temperature rise of a particular wire and isolation performance according to current and installation method. In battery installations, especially low voltage/high current, we need to know the max allowable voltage drop between the source and load; it determines the efficiency of overall system. Example: 1mm^2 copper can withstand 1kA(temp rise can be about 800C, isolation will fail, conductor stays), but that size is an inefficient conductor for a battery installation; voltage drop squared=power dissipation. The right question here is, how much do we allow to lose? Aluminium has about 2x less electrical conductivity per sqr-mm, but its an ideal conductor to make contacts between the batteries aluminium terminals(near 0 electrochemical corrosion). Problem here is: where to get aluminium bridges that are mechanically soft (woven belt like conductor with aluminium terminals).
BMS and the right place of balance/measuring wire is also dependent of the current draw/voltage drop between the batteries bridge terminals. To minimize the voltage error(adds to voltage drop of the bridge between batteries and its temperature dependent) the right place of single series connected battery assemblies BMS wire connection is the midpoint of the bridge. That way we ensure, that the voltage drop is symmetrical between two series batteries, and its absolute value is independent of the overall load current(charging and discharging of the battery represent a load to the bridge connector, only the current way changes not the voltage drop polarity).
Too much information for the first time. Next time I will introduce You to the secret world of electrochemical isolation and hydro isolation of marine installations. Maybe will type some musings of electric drives also... If You, and the respected public, are interested.
for marine purposes you have to solder all wires. In the long run humidity shall corrode connections. Been boating for more the 40 years. Had my portion of corroded bad connection LOL
Happy Holidays to you and your Family
the important thing is to calculate the voltage drops .. singularly and end to end .. then consider whether it is SIGNIFICANT .. there are always variations as you know .. the aim is to be better than the spec ... a few calculations loaded in excel and you have it ... if it is in the ok range .. then you can determine the physical attributes as to length and stresses on terminals .. how it affects your long term mechanical stress on the terrminals /batteries .. smiles .. which i agree with you .. critical over time in moving dynamic environment .. you are doing excellent work .. i have found over many years of computing it is more relevant to ensure imaCULATE connection/contact resistance by using no-oxide A or similar to seal the joint from atmospheric attack and verdigree build up.. MEANS LESS MAINTENANCE OVER TIME TO TRACK .. opps .. erroneous problems in a stacked and loaded system.. hopefully none.. but reality is always MURPHY comes to town ...lol... merry xmass and happy new year to u and urs !
Merry Christmas, and yes you will have to tell your Victron the voltage to charge to. 3.65 x 16 = 58.4 (but I would set it lower).
"Ray Builds Cool Stuff" tested the resistance on the bolted battery terminals
Looking good.
Power supplies/batteries create or are a voltage difference. Just add a 5V power supply in series to the battery. Attach the negative of a 5V power supply to the positive of the battery, then there should be (battery-voltage + 5V) between the negative of the battery and the positive of the power supply. It's the exact same thing that you are doing by putting your battery cells in series. Iirc, Andy also seemed to be wanting to use a powersupply to create the full voltage to boot the bms. Even a simple usb power bank will do just fine.
Resistance in any conductor is directly proportional to the length. If you want to lower it at a specific needed length you need higher GA or put more in parallel. To see how much the resistance of the wires influences things, you need to know the internal resistance of the batteries. Then you can see if that % is significant or irrelevant.
You can also boot the JK with a 9V battery. The Bluetooth range is limited because the module sits in a metal enclosure. You could actually put an external antenna on it, but it requires you to take the thing apart.
How do you boot it with a 9v?
@@TheDigitalMermaid I'll send an email since I can't post links...
Can also write it here that Andy uploaded one of the manuals for the JK-BMS under the BMS section, that also show how to do it. There is also another YTvideo that show this I linked to under the Andys JK-BMS-video comments.
I thought it was as simple as putting a 9V battery in your enclosure, adding a momentary switch and putting the pos and neg across the P- and B- on the BMS? All it requires is a voltage greater than 5V. A 9V battery is cheap, small and easy to replace than needing a dedicated workshop powersupply or using your generator on the boat just for a >5V jump.
@@zoe..d Yes, I just wanted to put a link to the manual/diagram to make it clear that the + of the 9V battery needs to go to B-.
Probably not relevant today but love your enthusiasm..
Very interesting that you are paying attention to the cell to cell resistance. I'm a person of simplicity and would like to say; I wouldn't pay much mind to the resistance values from that meter. Verifying the resistance of the buss bar over your home made paralleled 10AWG jumper you should be measuring at micro ohms with at least a 3 amp to 10 amp current signal calibrated to conductor temperature. lets agree that's really not necessary for this build however nice. Unless you are building to sell and you are trying to pinch pennies for production. The 3 points that matter as you build your battery. #1 resistance needs to be low at each cell connection, #2 resistance needs to be low in the connector from cell to cell. #3 the connector needs to be flexible for expansion and contraction of cells during transportation, heating - cooling from charge discharge cycles.
Address #1 make sure the cell post contact area is flat and smooth, clean, and big. You can only ensure you clean the post and use as much of the post you can with your cell to cell jumper lugs. Address #2 from what I see of what you built, the 1'st option is perfect as long as you are allowing for 125% max current the lugs you are using have what looks like adequate surface area. Address #3 the short size of the 1st jump which has enough elasticity required, as nice as that 2nd loop jumper is you don't need to over build as in that example. What I mean is different length #10 cables and a big loop adds more that can go wrong than right. Finally need to be sure you clean the lug and use stainless hardware with a beveled washer pointed correctly, and torque each and every bolt as specified by the battery manufacture mark each connection after you torque it.
PS. use de-natured alcohol for cleaning connection points avoid using greenies you want smooth surfaces to contact each other. and please put some venting in that wooden box top and bottom...
Thanks for the kind words. In the most recent video, I do test with a micro-ohm meter after I was kindly gifted one. :)
On the victron check that you have a tail current of something low (like 0.1amps). It will then stay in absorption longer to slower more filling the battery at the top end when charge suddenly drops off.
Maybe I’m wrong about this but helps me on my MPPT. I’m pretty sure the multi and Quattro have similar settings.
Have 1/16" thick aluminum busbars made. The ones I made IIRC were 1.5" or 2" wide. Because they are thin the flex if required to make good contact with the terminal end. I have a few spare I can send you if you want to test them.
Very kind of you to offer. I think I'm settled on the shorter 4x 10awg though. A big reason being that I can make them as I need them, even later when on the boat. You might want to check with one of the other, more testing focused, channels though. Cheers
There’s many ways to figure out bus bar/wire resistance and the losses on your LifePo4 banks. You can measure the mV voltage drop while under load and even figure out the Watts lost in each connection. You can measure the width x thickness like 2mm x 20mm and use online charts to show the resistance per inch of foot. You can use a thermal camera and under load you can see the connection quality and losses for each connection and the entire battery at once to spot all the high loss spots you need to correct. You can also check a few types of bus bars at the same time with a thermal camera. You could heads up compare a solid copper bus bar, the flexible 10 AWGx4 and 4 AWG while under load and you will see all the problem connections stand out instantly. Also check wire charts as true Gauge properly made pure copper 10 AWGx4 and 4 AWG have almost exactly the same resistance per foot.
The millivolt drop with a set load in Amps will allow you to calculate the resistance without a milli ohm meter and show you how many watts are lost at that junction. Does your fuse drop 40mV when under a 100 Amp load? So is your fuse wasting 4 Watts and how many kWh’s will be lost over time? How about your switch? You can even figure out the losses in your BMS by the voltage drop on a load. You can even figure out the total losses and efficiency of your battery as a whole. Is only 80% of the kWh’s going to the motor or 98%? You can measure the voltage drop under load and know.
Also there’s also pre-made copper "braided" “flexible” busbars. By using 4AWG busbars instead of 1/0 or 4/0 are the total losses of all connections on all 6 battery banks at 100Amps causing you to lose the 20% of energy of an entire battery bank or just 1%? You should know as 20% would be like having 4.8 battery banks not 6. I’m just trying to get you to calculate the total losses NOW and it should have been done before you started as you might find cutting 1 pound off of bus bar wire might be like losing 2, 5 or 20 or 50 pounds of battery capacity and battery cost and charging losses and boat loading and motor efficiency due to added drag. Also what will be the bus bar battery losses at 10%, 50% and 100% throttle? Using 4AWG or 1/0 or 4/0 AWG bus bars. It’s pretty easy to figure out.
Personally I would have a FLIR thermal camera with me at all times as there are 100’s of problems and uses for it inside a boat and a laser thermometer gun. You can quickly spot a crimp or terminal failing on all your battery banks at once. Using an ohm meter on 100’s of terminals takes forever and is hard work on a boat in the water. Even when you’re done you won’t know what side of the terminal or crimp is the problem like you can with a Flir Thermal Camera. Even the phone Thermal camera’s like a $200-300 FLIR one or FLIR one Pro are plenty good for this. You can spot hull delamintion and weak pipes, bad insulation, water leaks and intrusion and endless other stuff like hot spots on solar cells and bad wiring!@! all over your boat. Google and look at a bunch of FLIR thermal images of Marine Surveys and hull delamination.
a different option could be to unhook the bms and charge each cell individualy to half charge that should work wen you hook back up the bms.
I was thinking about making busbars from 2/0 cable, short as possible, using welder cable, for a peak of 250 amps, I was hoping resistance would be low, and still be flexible!
You should try making some flex bus "bars" with multiple thin flat stock. I bought some but they haven't come yet, to see how they are made. But i think it is just multiple thin flat stock.
flat stock would allow for up and down motion, but not rotation. I wanted to absorb movement in all axis with minimal transfer to the posts.
@@TheDigitalMermaid that is true. wish I had thought of that before ordering 7. they ain't giving those away. lol.
On my last two 8s 105Ah, packs I built, I made my own but they were so short, they really didn't have much give. I think I'm going to do those two packs over with these curly bus bars. they kinda look cool too. have you tried the braided type used for grounding in vehicles?
@@immrnoidall I haven't, but Andy did, and I can't say he was impressed. He tested them at the same time as he tested the two types of "flexible bus bars" I made. The ones I chose to build for my boat are the 4x 10awg ones, as they give the best flexibility in all axis of movement. th-cam.com/video/EjBqng70ORc/w-d-xo.html
@@TheDigitalMermaid 10awg, that is great i have about 20 foot of fine strand left over from my truck amp install.
@@TheDigitalMermaid blue tooth slowly died and finaly stopped working. uninstalled the app to reinstall and nope. will not install . installed a bunch of other stuff on the phone fine . not this JK bms from hell. and no support from seller or anyone. TRASH.
Was surprised that you wanted to add length back into the bus bars.
if you look on the back of the plug you find a strip gauge also if this is for the boat you said it was for your shore power. Shore power will be a 30 amp 120 volt twist lock ore are talking about pluging into the 120 volt outlet in your boat
It's good to see a very competent girl into it ^^ It is so much man oriented in general ^^
There was a video i watched where someone used one extra battery somehow with their pack to start the bms up (like a 6v or 9v).
i got a jk bms and plan to be without mains but it has the extra screen and button and the renogy rover charge controller has a lithium wake up function provided there's sun.
i hope you work out a good solution
I ended up swapping to the BMSes with start switches. Had I not been able to, ya, anything that got ~+5vDC would do the job. Cheers!
Couldn't you use a simple double pole switch with a 5v+ reduction resistor to momentarily connect a drop in battery voltage to trigger it to start? Also I'm curious how my battery busbars would perform vs your flexible. I used copper pipe that I flattened into busbars and drilled holes in each end, but for relief as I was worried about expansion, I made the DIY copper busbars 1 inch longer than needed and bent a small 1 inch wide V in the middle, which gives the busbar the ability to expand with the batteries if its ever an issue, since the busbar is able to move pretty easily with that V bend in the middle a slight amount.
If you have the movement problem, why don't you fix the batteries together then? You will even get a bonus with more cycles to then? (First time watching the first video from you) cheers from 🇧🇻
To turn on the JK BMS. Just buy their LCD... It has a power Button. And the added bonus of a visual status of the Battery (Voltage, capacity, current).
I've got it on order!
One problem with the "LithiumSolar loop" idea is that each loop has more inductance than a straight-ish wire. This higher inductance will cause trouble during load transitions in your power system, such as when turning on or off a large motor, which is yet another reason for you to return to your original flexible bus bar idea.
Huh, I didn't think about induction. I'm curious if it would actually be noticeable at 150A, but it could be. Thanks for the insight.
It makes zero difference, we aren’t talking about fine electronics here, this is all brute force dc
Hello friend I watch a lot of your videos
You were stressing over not having a 5v battery but the requirement is greater than 4v so you can use (3) AAA in series or a 9v battery which is a much simpler method. JK also now offers a display that has a built-in on/off button.
That button is sitting on my desk right now. I'm hoping to finally work on a video showing it after work today. :)
0.19 mOhm loop busbar have inductance and its not accurate to measure it like this. I suggest to make Voltage drop in ohms law.. but flat metal busbar is the best. i am making aluminum bubars for my cells with length of 14 cm and resistance 0.074 mOhm
I figured that out in a later video, and then redid the resistance tests.
How do I make a 64S BMS if I only have 4pcs of 16S BMS?
Do I make 4units of 16S batteries, then connect all these 16S batteries in series (of course only through the BMS)?
A 64s pack would be 204.8v, I'm guessing that's not what you actually want, is it? If you mean to run all 64 cells off one 16S BMS, then you could create 16 separate 4p packs (connect the positive of four cells together, and their negatives together) to create a single 3.2v cells with 4x the amperage, then connect those 16x 4p sub packs in series. This would give you a 16s4p config at 48v.
@@TheDigitalMermaid Actually, yes I want to make high voltage battery bank using just 16S BMSs. I am thinking it would eventually fail because they wont balance each other.
Why High voltage? Some inverters use high voltage to reduce current draw and heat on the batteries.
So I assume if the JK BMS is connected to a 58.4v charger, it should activate once the charger plugs in?
No, I believe it requires +5v across the B- and P- leads.
Given the cells are quite "snug" within the box (I forget if you bound the cell blocks with fibretape or something else) it is "So Unlikely" that the cells will ever expand or contract to any noticeable point. They will ONLY swell is you over charge at a Hi C-Rate or Over Voltage which is not likely with the system being setup properly. I've read & seen vid's by Marine Folk and most of them use the standard busbars. The fixation on flexible to this extent honestly seems too overkill.
The JK will also show you what it sees for resistance per cell, will be interesting to see you compare those readings with the TR-1035 tester. One you do that, "Just for Fun" then replace one of your "fancy flexies" with a solid bar and see what the JK & TR say in comparison. Might be interesting.
BMS -B -P wires are AWG-7. 2x7-AWG = 4-AWG. One Option to extend wires, you can use a 4-AWG Barrel Connector and extend with a single 4AWG wire to Lug.
BMS Sense Leads are 22-AWG
22 AWG x2 (folded over as done in this vid) = 19 gaugue effectively.
Excellent Wire Gauge calculators here:
www.wirebarn.com/Combined-Wire-Gauge-Calculator_ep_42.html
Keep in mind, "marine use" is a very broad classification. If I only planned coastal cruising and the loss of power meant I lost my fridge, i'd agree that I am obsessing too much.
In my case, I will live on the boat and I will be doing crossings. I will be sailing in bad weather and pounding seas. The shock loads will be fairly frequent and strong, relatively speaking. Also, my batteries are my house bank and my fuel tank.
The loss of power, or worse, over heating from a loose terminal when I'm off shore, have significant consequences for me. In this light, I don't think it's unwarranted obsession.
Almost all the batteries i have seen disassembled have welded busbars so i am pretty sure they are not worried about expansion . Ask Andy .lol.
I don't think I've ever mentioned being concerned about battery expansion. My concerns are about shock loading on a large 16s pack.
Hi... How can I synchronize the BMS JK so that it gives me the most accurate load % readings?
Hi, how about Tinned Copper Earth Braid For Battery Earth Straps & Cables 19mm² 130A. You could mimic the busbar with a 6mm lug on each end?
Two reasons; First is that the few I found cost a fortune, and this method is something I can make on my own anytime.
Is 150a bms large enough?
Think each bus bar as small resistor. That includes ring terminal. In series resistance increases, in parallel it gets half. Ring terminals are always weak spot. Because unlike wire that has lots of strands to carry current. Ring terminals don't have the same amount surface area. Try 2 two wire ones in parallel might be better than one 4 wire one.
Also 10AVG silicone wires have difference. Most chinese wires have 1050 strands of 0.08 wires. When i got my self 8ne with 1946 strands of 0.06 wire. Core does not matter only surface area of the wire.
The surface effect isn’t an issue for DC. It only matters at high frequency AC.
Hi Digital Mermaid, new subscriber to Andy's channel which sent me your way by his recomendation. (Yes, new sub for you :))
You've gone to the detail of checking internal resitances and logging for each battery, terminal.... and derived the relationship of resistance with diameter and length, does your BMS allow for different resistance values across each of your balance leads? If they are different lengths or trimmed down to reduce excess and have a neater install, would there not be a difference in behaviour from the BMS charging a cell with the shortest balance lead vs longest due to the reistance of the balance lead itself?
Keep up the good work and learning!!!
Would it not be more practical to protect the battery box from vibrations then going down the rabbit hole and protect every connection? example put the battery box on rubber feet of sorts?
I will try of course, but the weight of the battery boxes and how hard you can get pounded on the sea, it's impossible to prevent shock and vibration from going through.
@@TheDigitalMermaid I saw another youtuber who also is building a battery pack with the same type of cells and he used flexible bussbars, kind of a copper laminated busbar. maybe an option?
@@nordexo That was LithiumSolar! I chatted with his as I did my first flexible bus bars at the same time he made that video. He's the one who gave me the loop idea.
Isn't it a bit exaggerated to have that much springiness. How much can the batteries move, really?
It's about absorbing even small movements so that those movements don't get to the bolts
It appeared as though your fingers were touching the ring lugs when you were measuring the resistance. That will give an inaccurate reading.
resistance to poofy cat is futile
have you added some kitty litter to the other box yet
Ha! I think the box is too small for my kitties to appreciate. I love that idea though!
You connected the BMS wiring before you connected them to the battery after you crimped the connectors on. So if you did make a short. You harmed the battery AND the BMS.
Where do you order the JK BMS? I’m from Texas
Aliexpress, I think I followed Andy's link
@@Digimer ok thanks
Merry Chrimmas!
WHat flavor juice are you drinking?
Smokey.
I think it was Té Bheag Scotch.
Energy will flow trough the lowest resistance. This might overheat your flexible bus'bar'. Your battery should NOT be able to move, so you do not need flexible busbars. When you use cells that allow movement, the friction between the cell might create a short.
So the cable resistance is twice the cell internal resistance ... you're going to be losing more power in the links than in the cells. Wire sizing is partly about heat (melting the wires is bad!) but mostly about power losses. With 16 cells at 0.03mO for the solid links vs .15mO for the wire and 0.07mO for the cells you've got power losses of I2R, so at 5kW = 100A draw on the pack you'd be losing 11W in the cells, 5W in the solid bus bars or 24W in the wires. Which isn't really significant, saving 20W on a 5kW load when you're losing that much in the battery monitoring system or inverter isn't really critical. IMO anyway. I'd be more concerned about the solid bus bars not aligning perfectly with the terminals and giving you unexpectedly high resistance there. FWIW you might be better bolting the links in place then measuring from bolt to bolt on the batteries would be more useful.
Thanks for the math! Ya, I'm not at all keen on rigid exactly for that reason. The slight additional loss is well worth the mechanical benefits.
but the heat on the busbars transfers to the lithium cells degrading battery life significantly by ~1000 cycles per 10*C
I dont understand why u r making a flexible bus bar when the batteries r not flexing anywhere because they r in the box that dont flex?
Shock loads from crashing through waves will transfer into the cells, even in a box
Hello, Can I ask here Question?
Yup
@@TheDigitalMermaid
Thanks you, since we connected both end of battery with charging system via bms and individual we connected each battery with wire to read and balance, here Question How we stop ✋battery from charging while next battery still charging via bms I'm still not clear about way of charging?
I actually don't understand why anyone would think a wire would transfer electricity better than a copper busbar. That would never have entered my mind. Maybe try reading conductivity instead of resistance or something else. (better meter)? IDK
im seriously confused on why 58v was needed to wake the BMS. Its a 48V battery. WHat am I missing here?
'48V' isn't the nominal of this battery, it's just a general indication. The actual nominal voltage is 3.2Vx16=51.2V.
To add to UpNorth, when the pack is closer to full, the voltage increases even more. You then add 5v to get the JK's startup voltage.
Can also read the JK-BMS manual on Andys site under the same BMS, that I sent to him.
You know that 0.03mOhm at 100A is only 3mV drop. 4 series means a total of 12mV dropped in the bus bars for a total of 12mV*100A = 1.2 watts.
In the grand scheme of things, that's sod all squared given it would be a 1.2W drop on a 4800W circuit! Surely you have bigger ghosts to hunt?
The only concern with bus bar drop would be the error factor in the cell voltages being out by up to 12mV could effect balancing and cell monitoring and tiny, tiny, tiny little bit. Surely nobody runs their tolerances that close.
Should point out the current shunt in the BMS will probably drop 10 times that voltage. You could remove it and just measure the drop across a bus bar. It will be very hard as it only drop 12mV at 100A. The BMS's shunts will be more like 0.1 or 0.05 and drop more like 2 or 3 watts just measuring the current.
@@1over137 aye, and thanks. The focus turned to flexibility more than resistance as the build progressed, for just this reason. Thanks for the post!
It so doesn’t matter even at all, just make the same lengths
Longer wires have more resistance - who'd of thunk it!
Well, I mean, ya of course. Two points; First is covered in the very first video, "I'm new to this". Second, I knew before that there was a difference, but the amount of difference was unexpected.
@@TheDigitalMermaid. I think @Chris M is just been sardonic!
@@teddypreston5525 Possibly, but I try to give everyone the benefit of the doubt and give genuine answers. If not for the person asking the questions, then for people who might find the conversation in the future.
@@Digimer Point well taken, thanks.
@@teddypreston5525 Think of it more like English humour than being sardonic.
@21:00 a "cat scan"!!!
Ahaha! I wish I had thought of that in the video.
@@TheDigitalMermaid I’m still waiting on laminated buss bars and have not powered up my JK BMS. Can you tell if they do soft start when turning on? Maybe a pwm duty cycle for a second or two?
@@ai4px I'm not sure what you mean by "soft start". I think of inverter and motor study starts, but I'm guessing that's not what you mean. The BMS beeps, and starts supporting power. I've not connected a load and plotted amperage.
@@TheDigitalMermaid I’ve used the chargery DCC module and when it turns on it does an increasing pwm duty cycle for the first second or so. Saves spikes caused by inverter caps. But…. It is an idiotic design because the DCC soft start only happens when you manually flip the power switch and never from the remote on/off connector. I blew mine up after two or three iterations. Now I used a pre charge resistor across a gigavac contactor.
Ido not see the point of multiple wires instead of one. It just seems like a lot of work for little reward.
It was covered in an earlier video. The 1x 4awg strand was too stiff, the 4x 10awg is a lot more flexible.
As I said under previous video, you are still way too much complicating things. Compress the battery with sheets between them -> ignore vibrations and dilatation. Use rigid bus bars. Simplest, cheapest, most effective. You are inventing dead ends which is fine if you want to play with it, I just hope other ppl wont try to copy it.
I've explained my reasoning throughout the build. If you think something in my logic is wrong, cool, explain why. I've changed a lot of my designs thanks to productive feedback. Simply being told that I'm wrong isn't very convincing though.
@@TheDigitalMermaid First part was in my post under fancy layout video. Instead of 15 short and one long cable, you got 16 medium long cables. Design that was more difficult to make, required a map to figure out battery order and put high different potentials close together so accidental shorts would cause more sever damage. You try to improve things. Trying to make it better is fun, but thousands of ppl already tried that, we don't need to reinvent hexagonal wheels. There are engineering codes and recommendations and one of those is keep it stupid simple, because it will be more robust. You can easily repair/replace things and you will understand the design years later without a map. If long positive/negative cable heats too much, you can use thicker cable or even copper bar, no need for overcomplicating things. Most manufacturers nowadays already recommend compressing the battery, because it will give you 30-40 % more life cycles which I think is pretty significant. It's in the battery's datasheet, manufacturer knows why he put it there, yet you still prefer not to do it. You are afraid of vibrations and movement despite if you compress the battery with sheet separators, this would be non-issue and you can use copper bus bars. As you've measured it, they are superior to cables and you can use thicker ones that you've measured, lower losses and less prone to build errors (bad joint lug-cable). In engeneering less build steps is always better - faster and cheaper to make, more reliable, less space for errors and failures later. There are simple and verified solutions. Trying to outsmart everyone and make something better usually leads to worse results. If you do something differently than what everyone does and what is recommended, you should have pretty good reason, but I don't see any. What I see is that first deviance from "usual" leads to necessity to change other things and compensate for insufficiencies of the change. Yet that change is not needed in first place
@@MiH1IT One of the things a lot of manufactured solutions do is chase cost of manufacture. Stamping copper bar is a lot cheaper than making cable connectors, as an example. So the argument that manufacturers have come up with the ideal solutions is valid _if_ you accept that all projects have the same goals and focuses. To be clear, I do not think I am smarter than others. I have made this pretty clear since my very first video. What I am doing is explaining through these videos what _my_ focuses are, and trying to figure out what solution works best for me.
The goal of this channel is not to be a recipe for others to follow. Its goal has been to show the process of learning and figuring out what works best for each person in their own projects. The idea that we shouldn't bother because we'll never be as good as the experts would be to argue that DIY is fatally flawed in principle. I think we'll have to agree to disagree on this.
@@TheDigitalMermaid I did not say that it was solution that manufacturers only use. In our (my country) solar diy community I see 90+ % bus bars, same if I check "solar lifepo4" in google photos and yt video thumbnails. When something is easier to make and works better it can still be cheaper. Just because it is cheaper or less complex, it does not make it worse. You use batteries that manufacturer said you should compress to get the best result, but you don't even trust the battery manufacturer.
@@MiH1IT The spec sheet doesn't say they should be compressed, only that the degradation of capacity to 80% of rated would change from 2500 to 3500 if compressed. As I explained in an earlier video, the batteries will age out before that difference matters to me in my use case. I'm not sure where this energy is coming from... I've explained my reasoning and rationale for doing the design I'm doing. It's up to anyone viewing my videos to decide for themselves if my logic makes sense to them or not.
a note on using specialty tools vs your desire to keep this to things that others can duplicate
If you use specialty tools that people send you to evaluate different options and show the advantages/disadvantages of the different options, others don't need those tools to build their batteries or to take advantage of the testing that you do with the tools.
Just avoid situations where you are using a speicalty/expensive tool for tuning things as opposed to the evaluation of different options like you did here.
Okay let's start again hello friend I watch lots of your videos I notice you located in Canada so me too perhaps you'll be kind and may be able to help I just bought JK BMS I am not able to download any the app I even try different phones I would appreciate so much has you know anything about this problem JK support do not answer any emails or text I hope you will be able to help we notice you have so many BMS thank you I'm sorry to bother you checking out John have a nice day
That drink glass is making me nerves.
How so?
@@TheDigitalMermaid Because it's right on your elbow as you are up down ,all around it.
@@immrnoidall Aaaah. I have spilled a couple over the build, ya.
I dont think u r thinking logically or critically. To me the most sense to me is if its resistance u r trying to lower than get a solid copper bus bar the size that they shipped with the batteris and test it to the one they sent with the batteries. It dont matter if u r in a boat or an rv those batteries r not vibrating out of that box they r in nor r they moving around inside the box so why r u try to make the bus bars flexible? Please help me to understand.
DO NOT CHARGE THOSE BATTERIES TO 3.65 VOLTS per cell. You will shorten the life of those batteries. Charge to 3.60 max per cell. Your maximum pack voltage should be no more then 57.6 VOLTS. Also don’t let the pack go below 43 VOLTS and you should be fine and you should get about 3800 cycles and more out of them. Also keep those batteries inside at room temperature.
With do respect, the data on the data sheet is the source of truth on what is safe. They're are times you want to do a full charge, and a capacity test which I want to do, is one of them.
The all-caps command to not so something leaves no space to assume the person you're taking to know what they're doing and has a reason for doing it.
Thought of another who if you have not watched his videos then I recommend you do it as he has tested a bit with internal resistance and on cables
reminds a bit of your videos that some are long
th-cam.com/video/tGmOFYDPHfQ/w-d-xo.html
one of many videos
and it is unnecessary for more people to test the same things to come to similar conclusions, but he is much more "careful" that everything should be the same