Parallel Batterie Bank with 44kWh first full charge after winter. Watch this voltage difference!
ฝัง
- เผยแพร่เมื่อ 22 ก.ย. 2022
- Today is the day when we fully charge the battery again after a looooong 94 days of micro cycling it during wintertime. I'm very curious what will happen and how the BMS will handle the balance situation. How large will the voltage difference be after such a long time without balancing? Will the BMSes shut down the battery banks due to a cell over-voltage? Will the situation get out of control?
Let's find out!
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Enfin à jour sur toutes les vidéos 🙃, c'est très impressionnant toute cette puissance emmagasiner et prête a être décharger.
I understand now why you say bat tre! (Batterie!!!!!) in title!!😁I’ve always spelled it battery and say batter y! Thanks for the insight and explanations. Keep safe and stay cool!
You're saying it wrong. It's battery 😁
Thanks for the video Andy. Well done, cheer's.
Thank you.
It is a great thing to have that full charge again finally. I had mine get to 100% a couple of days ago too.
I thought you will never fully charge you battery. You must have been away delivering batteries to far north QLD again.
Heya, oh wouw after +- 3 monthes those 3 battery pack's look still good balanced that's amazing you did a very good job
This is fantastic! I can't wait to see my packs fully charged one day, I kind of modeled mine after yours except I'm on a very tight budget so it's not nearly as organized or wired so neatly.
Thanks for sharing and as always keep building 👍
Thanks Todd. Net and clean wiring can be done without any budget, right?😉 Keep it as tidy as possible to prevent any problems. Velcro is great for that purpose and very cheap.
Thanks Andy, Pretty close balance after that time, good result.
Yeah, it all worked out quite well. I'm pretty happy (and relieved) about the result.
Cool video - looks like everything is working as expected.
Yes, it seems to work as designed. I was kind of hoping it would not be too bad but this is certainly a great result.
Just received 48 pcs. EVE lf280k cells today.....I want my inverter now! LOL
Fantastic!
Andy whats going on? SOC went from 100% down to 19%! Testing something?
I LOVE your videos. Can't get enough!
It's not hard when you have an EV and bad weather. I need more batteries!
Morning Andy, Go the Cats, clear day this morning.
Good video Andy. The overkill seems to work well and my JBD is similar. This bodes well for my future build.
Yeah, they all work quite well actually. Even the passive balancing is not effective, it still keeps the BMS from turning of from an over voltage. And that's the main thing.
Great news 🎉
It was so depressing to hear you say that winter was over. That means winter is starting for me. Looking forward to my second year of solar. As usual, Great Video.
Wait is finally over
Great video. I now have 5 batteries and watching the batteries balance between each other is interesting. Its kind of sad when I see mine discharge. 😁
Having them all balanced is like a relaxing afternoon with a cold beer 🍺 . Its interesting to see a battery charging another as they all balance each other. All mine are jkbms. Glad to see you with sunny days again! You should look into panels on a tracking system. In Southern California it works well. As credits are popular in the USA again the Hyundai panels are interesting. Never stop improving. Thanks Andy.
You picked the right BMS have another beer!
Thank you Andy, very helpful video. I have a Growatt inverter/controler (with JK BMS) where is not pssible to program absorption time so the only solution for me is to manually change Folat to 3,45 volts every month for about one hour so all cells balance and than I lower back the parameters after balancing. It is good to know that I could could it once every 3 months and not every month.
How does the Growatt charge your batteries then if it does not have absorption? Does it charge to absorption voltage and then immediately goes to float afterwards?
@@OffGridGarageAustralia yes after absorption stays 1 minute then straight to float is unfortunate.
Awesome comparison of the different bms! What happens if the inverter starts using power from the battery when the battery is absorbing?
Maybe check the busbar torque connection on the higher millivolt jk batteries. The busbars could be sliding or need retorqued..
Love your channel. Just purchased 32 x 3.2v 320ah cells to build my battery bank for my off-grid cabin. Love to have a chat one day. I'm in NSW.
Looking to buy 32 to 48 cells. Do you mind sharing price you paid, if they were what you expected and where you got them?
Nice one Andy, glad it all balanced so nicely, my own build seems to be taking ages. So I best stop watching TH-cam and get up and do some work.
Yes, thank you. Get some work done 💪
Thought you would connect both seplos systems to it after the full charge to get even more from the sun 😁
But nice to see that even without active balancing the top balance is still ok after this few months. Let's see what happens in the next months.
If you are up for it, do a review on your OLD battery cells: how many AH cycles, what they look like after years of use, did they bloat, how hot/cold you run them etc.
I feel that if you didn't have a 800ah battery bank and only had a 280ah battery bank the Heltec pack would have peaked and the BMS would have disabled your system. The others were well balanced or at least the Overkill Solar pack was. What do you think is causing the JK pack and the Heltec pack to drift over only a 94 day span?
Add the seplos batteries by connecting them to the busbars. We need one big battery family.
I really love the enthusiasm, around the PV & battery statistics.
It would be interesting to know how you use all this power?
Hot water, dishwasher, car, washing machine? What do these appliances use?
Have you got enough to drive them?
At the moment it is just the garage which is connected to the system, the pool pump, irrigation pump and the vehicle charger. And I have an extension cable to the house to run dishwasher, washing machine occasionally. The battery size is great but I need more solar, especially in winter time with lots of shading.
Cool
envious on this first 10sec. Here in the home of Oettinger it is not that good 🥶
Yes sistema👍☀⚡🔋🔌💡
Hook up your seplos batteries to get a comparison to cable length and capacity
Excellent video once again! Is there a difference in resistance between the types of bus bars?
Aluminium is higher resistance than copper, and especially so at contacts because it gets a fine high resistance oxidation layer almost immediately.
Yeah, aluminium is usually worse than copper but these bus bars are thicker and have therefore a better conductivity that the standard copper bars coming with the cells.
Here is the video with the calculations: th-cam.com/video/mdr5HZZRaTc/w-d-xo.html
Andy, You scrambled my brain😂 I'm still struggling on how to program my victron 100/50 smart solar controller 😱.
What's the problem with it? Did you watch the video where I explained the settings? They are also shown on my website:
off-grid-garage.com/my-settings/
@@OffGridGarageAustralia Hi Andy, I think you took my comment wrong, what I was saying was there was so much information for me, that my brain could not take it all in given I had not slept due to ill health , My system is so basic, and I'm still trying to get to grips with what could be described as a "Flintstone" system of 2x 300w panels 1x victron 100/50 controller, 1 x 1500w inverter and 4 x lead acid batteries. So your system is like startrek tech to me, I really love your style of presenting all your vids and I have learnt so much from you , Keep doing what your doing and I am looking forward to the next vid from you. My best to you from Not sunny not hot but very horrible UK.
Time to put a fridge in there to be closer to your beer!
Not a bad idea...!
Great design Andy, everything looks awesome....I'm building a similar 24Kwh / 48 volt system with x2 batteries to supplement my existing 27kWh 120VAC /24 VDC off-grid system...The new system will have a separate inverter feeding a standalone 240 volt load panel....I already have an overkill BMS but I think my second BMS after watching your videos is going to be a JK.... I've been looking at the Hanzor store and was curious if you know if the 150 and 200 amp black models (B2A24S15P or B2A24S20P) are compatible with the new screens and buttons??? Thanks for everything you do, as a marine engineer I Love the detailed analysis😋😋😋
PS I will of course order through your online link 👍
Thanks for your feedback and kind words. Yes, both BMS on their site are compatible with the screens and power button function but always confirm through their chat that it will. I'm not sure how much old stock is still floating around these days.
Super Video wieder!
Morgen nehme ich meinen 280Ah Seplos Mason Nachbau in Betrieb!
Das mit den voltages hat mich echt nochmal zum Nachdenken gebracht! Du lädst bis auf 55,2V? Und absorbtion mit 53,6v? Also 3,45v max und 3,35v absorbtion?
Ich bin jetzt bei wesentlich höheren Werten, die ich eingestellt habe (max 56.00v (3,50v) max und 54,40v (3,40v) absorb....
Werden die denn trotzdem voll, wenn man mit so wenig Volt lädt?
Lg aus germany 😎👍
I have a question on batteries how long did it take to get your battery cells from China from time of your order?
It will be interesting to see if your absorption time is enough over the summer to decrease those deviation numbers. I am predicting not, but I could be wrong.
Yes, I'm with you here. I won't be fully charging that battery often... aeh, maybe I will after upgrading the solar production.
The passive balancers won't be sufficient but at least no runners in any of the packs.
Where do you find your bus bar and how do you calculate whate size you need, just bought 4x6.9kw Seplos batteries I would like to connect in serie with a copper bussar to my Deye inverter.
I build my bus bar myself from a tinned copper bar I bought.
You want to connect the Seplos batteries in series? I don't think this is possible. They are for parallel usage only.
Hi have a hybrid 5.5kW 48v inverter charger with a 10kW (48v 200ah) Lifepo4 battery bank. I have this since June 2022. I and would like to increase the capacity by adding an other 10kW Lifepo4 battery bank from the same supplier but new. After having them
charged at the same voltage can I just put them in parallel knowing that the internal resistance of each battery won’t match (one old battery and one new one).?
Thanks for your advice.
Marc
Yes, absolutely, as long as the voltage matches, you can safely parallel them. Please put the appropriate safety gear ins place as usually (fuses, breakers, cable sizes...)
Did you guys remember from who Andy's bought his batteries? I found one at aliexpress with local stock (I live in Brazil), but beside new and without reviews, something feels wrong. :P
Thanks!
DON'T. I would not recommend buying any batteries from AliExpress. I never heard anything positive from such deals.
Have a look on my website with all the info where to buy them from:
off-grid-garage.com/batteries/
Hi Andy! A small suggestion. I noticed you made gaps between cells for cooling. It'd work better if you make perforations in shelves and big holes in shelf cover for convection.
I actually sealed all the gaps in the shelf with foam and silicon to prevent critters to get in. Holes seem counterproductive here 😊
I will see how war it gets in summer time and if there is additional cooling necessary for the batteries. As I'm going to add more batteries over time, the actual current will go down per bank and there the power loss and heat creation as well.
@@OffGridGarageAustralia The Australian critters, right :)
Andy: in a Video about settings/configuration I think you talked about a 5 hour absorption time. Is the 1A temporarily and 5 A your standard setting?
I have a 1h absorption time set in my controllers at 55.2V (3.45V/cell). This is purely to allo the balancers to work.
5h was just for testing purposes so I could keep this higher voltage for longer to run some tests with the balancers.
@@OffGridGarageAustralia Thank you for making this clear for me!
Do you have an overview, how many Ah got discharge through each of the three banks? Did the JK BMS and Heltec BMS get loaded more than the other and was maybe more unbalanced because of this?
Aeh... not sure if the BMS capture that and accumulates the Ah used or charged over time. I don't think so. The Victron Smart Shunt does it and the charge controller do it but not the BMSes.
The battery banks will be used the same way as they are in parallel. If one bank would get discharged more, the voltage would sink in this pack and therefore current would go from one of the other banks towards this weaker bank. So in fact, we would then discharge this pack less than the other one. This sort of balancing takes place 25/7 at any stage and ensures all banks are the same all the time.
@@OffGridGarageAustralia this may not be the case in the flat area of the voltage curve?
Hi Andy, and again a big thank you for this video, super interesting as often!
I'll give you my opinion, about the charging procedure.
I noticed and you can see it again on your video, that the first pictures of your 3 BMS when they are all at about a main voltage of 53.6V, the cells are all well balanced on the 3 BMS, and the percentage of 3 BMS indicates almost all 3 bms 100% charge (except the JBD, overkill but it's only 1 parameter to be rectified very slightly) even your smart shunt indicates 99% also nice!
For me everything that happens after, is useless, increase the load up to 55.2V and absorption?? in fact I believe that Victron just said that it is necessary to make an absorption charge on lithium batteries?
I have always heard that the charge of lithium batteries is constant voltage AND constant current. (no absorption?)
And why I tell you that the rest is useless, it's simply because after the floating voltage of the Battery packs, they will return to 53.6V, with the same percentage of charge, and the same voltage at the cells as at the very beginning.
The only thing we could see is that when you charge too much 55.2V and absorption, the cells are very unbalanced.?
For after, during the floating, come back as before.
It's a shame we didn't see the video until the floating was done.
I think if you charge your battery has a constant voltage of 53.8-53.9 or 54V and Floating has exactly the same voltage, without absorption. you will have exactly the same result, except that logically your cells will always be well balanced all the time. (obviously the test must be done with the same sun conditions, etc.)
The only concern that we may encounter is that the batteries will have more difficulty charging when the sun is less and it will charge a little slower.
Again Andy this is only my opinion, about the charging procedure, and with all the very many tests I have been able to do, without ever absorption, when I exceed 54V at the main voltage of the battery packs, this cause problems of imbalance in the cells. (but I admit the JK BMS is very efficient)
By staying at the Max at 54V (main voltage) or below 53.9-53.8-53.7 and 53.6V it's perfect!
The fact that the deviation is not high at 53.6V is not because the pack is well balanced but because we're still in the flat area of the curve and all cells have almost the same voltage, regardless the SOC.
So CV charging is basically absorption. The current is tapering off while the voltage stays constant. The cells absorb.
The only reason to charge to 55.2V is to allow time for the balancing to take effect. Nothing else. Only at this 'higher' voltage, we can identify the cells which need balancing. Going down by 0.1V per cell only and they all show almost the same voltage again.
If you charge only to 53.6V, the cells are not consistent charged. Voltage cannot be used to determine the SOC of these batteries. You can of course charge only to Float voltage and absorb at this voltage but again, inconsistent results/SOC and absorption will take forever. Balancing at this voltage is impossible. And over time, deviation will get worse without being noticed because the cell voltage looks the same at this point.
@@OffGridGarageAustralia Hello Andy and thank you for your answer, I understand what you mean.
And your videos are so well explained, that we just understand well, but example if I apply in my case it's not going at all.
And when you say: "You can of course charge only to Float"
I sincerely think that this is very sufficient, so that all the cells are completely charged, and that the SOC is at 100% or 95%.
For this reason, an example if you use a Growatt inverter, and you select the LI option for the type of battery, the Bulk charge and Floating charge are inseparable in setting (ex/ you set 53.9V in Bulk charge Automatically the Floating will be 53.9V and you will not be able to adjust bulk and floating differently) these are Factory settings for Growatt, in the case of the LI selection.
Even better, if you connect the communication between the inverter and compatible battery packs.
It's exactly the same, the inverter just looks for the SOC of the packs to show 100%. (and the inverter solar controller charges then stop, then recharges and stop.... and so on...) until the battery are full charged. (sincerely I don't like to operate it with communication, because at the end of the charge the inverter did only that, charge, stop, charge stop ...... for me it is not good for the internal relays?) but these are Growatt factory settings in colaboration with branded battery packs.?
The only thing I'm sure of, after multiple tests: if I push the Main voltage above 54V the problems begin, too many cells are unbalanced! and if I go above 54.5V or even 55V the problem is even greater, even with an active balancer this cannot be fixed.
(Attention all these tests in real conditions!! not with a power supply, because the charge with the solar controllers is sometimes different, and it is necessary to take into account, sometimes cloud shadows,
and consumption at the same time by the inverter which also varies, different loads, and all this sometimes changes the charge procedure)
On the other hand, slightly below 54V (53.8V-53.6) is perfect.
And the batteries are all at 95 or 100%.
Andy I think each case can be different, depending on the solar controller used, depending on the cells used, BMS too.
But in my case 3 different battery packs, different BMS too,
each time if I exceed 54V of main voltage, Problem.
And that's why I gave you my opinion, and what seems really logical to me is that after charging at 55.2V your solar controllers go to Floating at 53.6V, so in fact, for me to have pushed them that, does not bring anything good?
And when we see example, at the speed where the voltage of the battery drops, during a total stop of the charge (therefore logically discharged)
Having pushed the cells to these voltages (it takes time) and I think stresses the cells, so that in 1 or 2 minutes when the charge is stopped, the main voltage goes down very quickly to 53.5V-53.4V.
But without losing any SOC percentage.
This is really what I insist on, charged above 54V or more I have always found that it was useless.
But it's really good that we can share our experience, and especially that you make great videos!, it's really good, thank you again Andy.
Just get a Batrium already. Will integrate with the current victron setup with the pi and can hat.
Andy, you have 3 BMSes integrated with Venus OS over CAN Bus. What is the trade-off for this protocol instead of Victron's VE.Can?
I haven't connected any BMS to Venus OS yet. I did some testing with my second Pi but I didn't integrate this into my production system. Still unsure about the benefit...
@@OffGridGarageAustralia Then how your Victron Multiplus knows it has to throttle down the charging when near full capacity?
Different current between the packs is not necessary a sign of different SoC but of different pack resistance (kirchhoff rule). Communication between the BMS and the chargers would help the balancer keep track, especially for passive balancers with lower balancing power
Communication which slows down charging would be a nightmare. Imagine only one bank has a higher deviation but the other banks are fine and can take more energy and you slow down the charging for all of them. And with 150mA passive balancing, how much would you have to slow down charging to make the balancer work effectively?
Active balancing is the solution here. There is no real alternative in my opinion.
@@OffGridGarageAustralia You slow down charging only at the end of the charge curve when you entering the knee. That in fact is very positive because the reduced current avoids false balancing (because cells are peaking caused aof higher IR or bad cell connection and not because of different SoC) and, as statet, helps the balancer to do his job. 150mA is really very low, my passive Balancer has 1,1A (Rec BMS) per pack (having 4packs in parallalel, 44kWh in sum). Each pack has a BMS, communicating via master with the Cerbo.
In my opinion there is no need for an active balancer when there is no false balancing and the current is low enough so "bad" cells are not running away.
I am curious. The trees around your shop, Could you cut the tops off to allow more sun to the solar panels? Instead of cutting all the way down. Leave them 30 feet high or so? Just a thought.
Andy's said many a time it would be too complicated and expensive to get the tree's trimmed due to their height. The trees also help to keep the area cooler, and most of all they like the tree's. The solar appears to work perfectly well with the trees as they are. That said one of our trees is due a trim, which we need to get done soon.
Yeah, they are 30-40m high and it costs several thousands to trim them, so I rather invest this money in more solar panels and see how far we come. It's a good experiment for others too. If the trees are not yours you would not be able to do anything and have to live with this situation. So let's see if it is possible to get a decent result in such a situation.
Can you Tell me how the three bms are emergency shut down the mppt loader? I ask, because i am planning my second 14 kwh battery with a separate Bms
Once the BMS hits a protecting state (either voltage, temperature or current) it will disconnect this battery bank. The MPPTs will keep charging the other two banks.
If, for whatever reason, all three banks would have an issue at the same time (extremely unlikely), the MPPTs would go into absorption mode and supply a constant voltage (as set in the configuration) to the load and keep it running if there is enough solar. That works very well with the Victron MPPTs. Other charge controller may act differently if there is no battery present any more.
I was thinking of making a battery system with 1S but many P so only a CC CV system is required but this would need like 100-500 amp boost converter? 3.5v up to 12/24v ? No balance required and set to float so it should have a long service life?
Does such a boost converter exist? The efficiency won't be great. And think about the cable sizes 😮
@@OffGridGarageAustralia no I don’t think there is such a thing but the theory is using a cc cv buck converter to charge it would guaranty a set maximum charge and all cells would be balanced as perfect clones of each other. Only other problem would require manual disassembly at times to check the condition of each cell but for the majority of the time it would be worry free ? Maybe ?
@@maxgood42 I think the technology we have these days is great and works well. BMSes, balancers, that all works with batteries in series and I haven't heard of any other development to change that. But yeah, interesting thought...
Hi
Lifepo4 Battery bank suppliers do not recommend to put them in parallel if they are not from the same batch same capacity and with the same internal resistance.
From your video I understand that this is not required and that I can parallel 2 Lifepo4 battery bank regardless of their age or capacity right?
Thanks for your help.
Yes, that is correct. I have now a 2 year old 280Ah and a new 135Ah battery bank in parallel for a few weeks and use them without problems (it's in my video here on the channel). It does not really matter what batteries you put in parallel as long as they are the same chemistry and voltage.
Hi Andy, I have been waiting for a full charge to compare the Overkill BMS. I have had mine running for about 12 months and the same as yours started at 99% and over 3-4 months it slowly works its way down to 90%. I have reset mine to 100% a couple of times now and the percentage continues to dwindle. I normally get a full charge almost every day here in sunny Vic so different scenario from yours but same result. Any ideas anyone?
A parasitic draw? From what I have seen 80 % is a good amount to charge.
What are your charging parameters, Glen?
@@OffGridGarageAustralia Growatt 3Kw solar charges to 3.40 and victron 1 Kw solar to 3.45, 3.40 Balance on, 3.45 absorption 1Hr, 3.35 Float
sollten die Batterie-Zellen nicht zusammen gepresst sein?
I went tankless water heater after seeing how much power it was using.
Good vid and info as usual Andy. I was wondering if the JK pack has had more testing done on it previously that it has more trouble keeping in balance, but you may be right about the aluminium bars too being an issue there, either way I still think these small mA variations were more than acceptable given the time from last full charge.
Andy, can we buy u a beer or donate using PayPal? I have had issues with using cards over the net lately. Cheers
Yeah, I was really please about the result after such a long time and using the battery right at the bottom for many months now. Good to know, it is all working even after winter and I don't need to manually balance anything.
The donation link on my website is for PayPal. Thanks for your support, Evan!
off-grid-garage.com/
Andy... My 10th cell on my battery pack, with the same jk bms, has the same unbalance problem.. Less mV but same tendency... Only a coincidence
Awesome Andy.
Wow, your Victron BMV shunt was amazingly close in calibration after such a long time since it was synchronised. I fully expected it to be a long way out. I’m intrigued to know what settings you have in your Victron BMV for charge efficiency, (I’m currently using 99%) and Peukert exponent (I’m using 1.05).
You must have fabulous matched cells for the balance to be that good on the other BMSs with such low balance current. IMHO 150mA or so of balancing really is pretty useless on such a large battery bank.
(BTW I’m delighted with my JK BMSs, couldn’t be much happier, though haven’t fitted my replacement 12v one in the caravan yet, only given it a brief test, but it’s working well.)
Mine is also super accurate after a month - I always fully charge one a month - Charge efficiency 0.99 and Peukert 1.00
@@petermerle Thanks.
I’ll probably be able to finesse those settings slightly, maybe just drop the Peukert slightly, though I’d actually prefer the estimate to be slightly pessimistic rather than optimistic. (As I understand, Peukerts is of little to no effect with very low charge and discharge currents anyway, however even a 0.2C discharge will see some voltage drop so I would consider by my understanding that 1.0 is too low. Maybe I’m just being too pedantic LOL :-)
Thanks Dave. I have the settings of the shunt on my website here: off-grid-garage.com/my-settings/
I was surprised myself, that it was so close to the real SOC...
hello andy ,
i really hope that you see this comment because i couldn't find and an answer .
let's say you have two sets of panels and two charge controllers , you connect them to one battery .
the two controllers and the battery leads are all connected together in parallel at the same point .
how does the charge controllers differentiate between the battery voltage and the other controller voltage ?
why doesn't the second controller see the first controller voltage and thinks that the battery is full?
Great question. Both solar charge controllers will see the same battery and same voltage. One controller will not have a different voltage as the other controller. That is not possible as long as they are connected to the same battery.
@@OffGridGarageAustralia the charge controllers do have the same voltage , but the battery that let's say %50 is lower voltage.
Hi Andy I have a daly 500amp smart bms that failed. It won't stop discharging. Do you want it. Could be an interesting video. I'm in Beenleigh. Or I can send it to you. Thanks luke
Hi Luke, have you tried to update the firmware? That may fix the problem...
Like #92, now I have to quit eating lunch...
Hello Andy. Would you know why when I charge my batteries in full( in my case 56v with 3500w. The deviation on my JKBMS is rising up to 100 or 200Mv and of course after charging it goes back to 5Mv after only 1 hour (discharge in usual is around 1.5kw. ?
This is normal if you go up to the >=3,5V per cell range. Below 3,4V the cell voltage difference isn't really a problem, because the charge/voltage curve is nearly flat here. So capacity differences does not show up in a voltage difference.
You can try a top-balacing up to 3,65V per cell and check if this gives better results. But if will start to drift again over time. I just would say ignore the deviation. It's not really relevant.
@@matthiash.4670 thanks. My banks have only 2 month. And I charge them at night sometimes to 3500w in low grid price when it’s rain. And this happen in this case. I was not too worry. But a little bit!😁
As long as you don't have a runner cell, it is all good. While charging at such high power, you can probably lower the charge voltage to 55V and stay safe.
@@OffGridGarageAustralia i have one picking up alone! I will order tomorrow 2 more battery pack to have 4 in total. I’ve ask Quishou to replace one cell.
@@OffGridGarageAustralia JKBMS say to me. Protection (Cell Over Voltage) (OS)
I've also seen people stating that from time to time it is good to bring your LifePo4 cells to higher voltages for the chemistry to "reset".
Any truth in that?
If ‘higher voltages’ means: no more than 3.65v, then maybe so, but i would not charge a cell above it’s 3.65v max, I believe anything over 3.45v / cell can/will begin to accelerate potential degradation of a cell, but many may disagree.
@@evil17 I agree with you as well.
I'm sorry but I need to ask is 12v or 24v which is better I'm a pensioner so to me this is important
There is no better or worse, it's just a different system. It all depends on what you want to do with the battery.
Thank you so much Andy I appreciate your time from South Africa
Well well well. Who would have guessed that battery current will diverge as each battery comes up to full charge at a different time due to cell differences or simply different amount of discharge. Now consider the case where the chargers can provide more current. What will happen to the amp draw on the battery with the lowest SOC relative to its own actual capacity? It will go up naturally, perhaps exceeding the recommended charge rate, and in extreme cases even cause the BMS to halt charging. It's almost like I knew what I was talking about all along ... LOL
That LFP voltage curve makes it totally inevitable that the batteries will balance out when in parallel.
You could even connect one bank which is say 20%, and one which is 80%, and they will naturally fully balance over time because when the voltage starts to rise at the top of the charge curve, the lower voltage battery will take the available charge current. The reverse would also happen during discharge.
@@FutureSystem738 Put your thinking cap on then stare at my prior post for 4 hours. Hopefully you will then grasp what I was talking about.
@@retrozmachine1189 Yes, depends on the relative size of battery banks and charger.
Certainly it’s possible to charge one bank too fast, (but a good BMS WITH appropriate settings should protect from that.)
Anyway, we’re talking extreme cases here- normally something to avoid.
@@FutureSystem738 A typical BMS, in fact almost all BMSes, can only permit or prevent charging. Not only that, the configuration of the BMS is almost certainly going to be set to prevent charging at the maximum specified charge rate which is typically way beyond the recommended charge rate. The BMS is the safety net. Proper charge current control is the correct place to manage the system. This is not an extreme circumstance. Current going beyond the desired point is fairly common in DIY solar with batteries, but the person that built the system is oblivious to the situation. Proper charge current management is why commercial battery systems have comms with the charger/inverter and why the 48V 19" rack batteries often come with switching regulators integrated into the charge current path in the BMS.
@@retrozmachine1189 Food for thought. Cheers
I really don't understand how you get 100% charge on your JK BMS at that voltage... I barely get 75% or so for 53V... When I reach absorption at 55.2 V, I get about 85% SoC in JK BMS.
I have a Victron Smart Shunt so I take that as the real SoC, but it is just very confusing and annoying to have such a large difference in values for SoC.
I trust the Victron BMV Smart shunt for state of charge, especially after a recent synchronisation.
The BMS SoC figure varies and is relatively unreliable. I’m not even sure how it is calculated.
Charge the battery slowly to 3.65V/cell or close to this to calibrate the BMS.
The BMS SOC is actually more reliable than the Victron shunt as it measures directly at battery level and measures all the small currents which other shunts (like the Victron) misses. Hence the Victron needs frequent calibration. Especially the JK SOC calculation is pretty accurate once calibrated. You can see the voltages and current jumping around in the JK while the voltage in the Victron shunt stays relatively constant. It 'misses' some of the jumps the JK measures.
@@OffGridGarageAustralia Thanks Andy- I’ve never taken my batteries to 3.65v (and not entirely sure that I want to 😬).
3.55v is the highest I’ve taken them, and even have my cell protection cut off voltage lower than that (at 3.6v.)
Am I being overly cautious?
However I was certainly wondering how the JK BMS gets it’s SOC figure.
@@FutureSystem738 There is absolutely no reason to charge that high. 3.55V is great for balancing maybe once a year or even less frequent. In your case, I would only do this if I see an increased imbalance. But as you said, your cells are not having this issue anyway, so 3.4-3.45V is perfectly fine to get ~98% of useable capacity.
@@OffGridGarageAustralia hence why the BMS SOC is rarely calibrated Andy... I rarely charge over 3.45, in fact my settings are very close to what you have on your website, and thus the BMS SOC is way off what it should be...
It may be better once calibrated, but if calibrating it means brining the voltages to 3.65, then I'll pass. Happy to base on Victron smart BMS
👍👍👍👍👍👍🤓🤓🤓🤓🤓 ❤ ❤ ❤
Hahaha.. massive capacity
It's HUUUUUGE! 😂
Yes so spannend diese Batter. Mutter meint, es sollte in den Keller gehen
I was busy habe mir Videos zur. Stromverteilung von for trips to dispensary Sammelschienen angesehen. Das grüne Cannabis braucht eine Stromschiene Mach's gut . Good business in legal states of USA ja
Pure aluminum bus bars= 👎 Tinned copper bus bars=👍
Could be. I do more testing once it gets full again.
These conclusions on charging seem to blow the theory that all cables need to be the same length.
Yep.
I bought a Daly BMS to use with my 16 Lifepo4 cells. Have I made a mistake?
Yeah, they don't need to be the same length, definitely not. You also don't need to connect your banks from either end, so pos from one end and neg form the other end. That does not have any effect unless you pull really high current of ~1C
The Daly BMS will work, but... you may want an active balancer in addition...
You made my day. I have argued that. Ohm's law. Resistance so low its measured in miliohms per 1000ft. No one believes math
If it isn't accurate, why not get rid of the Scheiße Heltec? That would bug the crap out of most of the Germans that I know. Probably all of them. Maybe sunny, hot Australia has softened you, Andy?😆
It's a long term study, I guess...
Sorry to say but that's not fully charged. 99 percent sure.
Who needs 100%. Less is kinder to the batteries, and the last few percent does them no good at all.
Be kind to your batteries and they’ll last longer.
strange that comments are deleted so once again or simply time to unsubscribe ?
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