2:27 for Step by step top balancing instructions If you buy quality new cells, you can use BMS to top balance, then capacity test in a few cycles. That's the easiest way. Ian made a great point of using a blocking diode so you won't burn up the power supply. Smart idea. If you are quick charging, current sharing is an issue and you need to attach the positive and negative leads at opposite ends of the battery. In this video we are balancing and topping off at very low currents, so you can attach the leads anywhere. If it makes you feel better to attach at opposite ends, go for it. .1A on a 150A bus bar is not going to cause a current sharing problem. ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Does off-grid solar confuse you? Check out my DIY friendly website for solar system packages and product recommendations, and so much more! www.mobile-solarpower.com Join our DIY solar community! #1 largest solar forum on the internet for beginners and professionals alike: www.diysolarforum.com Check out my best-selling, beginner-friendly 12V off-grid solar book (affiliate link): amzn.to/2Aj4dX4 If DIY is not for you, but you love solar and need an offgrid system, check out Tesla Solar. Low prices and great warranty, and they can take your entire house offgrid with their new Powerwalls: ts.la/william57509 ~~~~~~~~~~~~~~~~~~~~~~~~~ My solar equipment recommendations (Constantly updated! Check here first): 12V/48V Lithium Batteries: www.mobile-solarpower.com/solar-batteries.html Solar System Component Directory: www.mobile-solarpower.com/solarcomponents.html Plug-N-Play Systems: www.mobile-solarpower.com/full-size-systems.html Complete 48V System Kits: www.mobile-solarpower.com/complete-48v-solar-kits.html DIY Friendly Air Conditioner/ Heat Pumps: www.mobile-solarpower.com/solar-friendly-air-conditioners.html Complete 48V System Blueprint: www.mobile-solarpower.com/48v-complete-system-blueprint.html ~~~~~~~~~~~~~~~~~~~~~~~~~~ My Favorite Online Stores for DIY Solar and Coupon Codes: -Current Connected: SOK, Victron and High Quality Components. Best prices and warranty around: currentconnected.com/?ref=wp -Signature Solar: Cheap Server Rack Batteries and Large Solar Panels: www.signaturesolar.com/?ref=h-cvbzfahsek -Ecoflow Delta Official Site: My favorite plug-n-play solar generator: us.ecoflow.com/?aff=7 -AmpereTime: Cheapest 12V batteries around: amperetime.com/products/ampere-time-12v-100ah-lithium-lifepo4-battery?ref=h-cvbzfahsek -Rich Solar: Mega site and cheaper prices than renogy! Check them out: richsolar.com/?ref=h-cvbzfahsek -Shop Solar Kits: Huge site with every solar kit you can imagine! Check it out: shopsolarkits.com/?ref=will-p -Battery Hookup: Cheap cell deals bit.ly/2mIxSqt 10% off code: diysolar -Watts 24/7: Best deals on all-in-one solar power systems, with customer support and distribution here in the USA: watts247.com/?wpam_id=3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Contact Information: I am NOT available for personal solar system consult! If you wish to contact me, this is my direct email: williamprowsediysolar@gmail.com Join the forum at diysolarforum.com/ if you wish to hang out with myself and others and talk about solar FTC Disclosure Statement and Disclaimers: Every video includes some form of paid promotion or sponsorship. Some links on this youtube channel may be affiliate links. We may get paid if you buy something or take an action after clicking one of these. My videos are for educational purposes only. Information is subject to change/update at any time. Electricity is DANGEROUS and can kill. Be smart and use common sense :) DIY Solar Power with Will Prowse is a participant in the Amazon Services LLC Associates Program, An affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com
DIY Solar Power with Will Prowse Do you ever resale any of the cells you test? Wanting to build a battery for a small camper project. Just thought I’d ask. And thanks for all the info in your videos.
Hello is it okay to top balance cell 4 cell, parallel 2 cell at a time ? and another 2 after, because i only have 3 busbar but i need atleast 6 busbar to parallel all 4 cell at the same time. thanks
@@BlazeByte21 I would think you could balance 2 pairs and then balace the two balanced pairs. But Iif I read your question correctly, you'd eventually have to connect all 4 to balance them equally. You need 6 busbars to do that. If you have some copper pipe you can make great busbars with a hacksaw, a hammer, and a drill for the lug holes. Cut the pipe into the correct length, ,smash the pipe flat with the hammer, and drill the correct spaced and sized holes. You don't have to have commercial busbars.......
Bruh!! Largely because of you and what I learned from watching many of your videos, my family had a battery backup for fridges and fans in place after hurricane Milton. (Multiple 24v battery packs of 3.2 lifepo4 batteries, with BMSs, on a GroWatt inverter.) Thankfully our power came back up before I needed to pull out the 4 400w solar panels to start to recharge. …man was I proud to have that in place for me and my family. Thank you sir!!
Anyone building a DIY battery pack should follow these instructions. The last 48V battery I put together a couple of months ago was needed for a scheduled neighborhood transformer replacement power outage and unfortunately the Chinese prismatic cells did not get delivered until late the day before. Fortunately I had the cabinet, buss bars, wiring, BMS & cell balance board ready to go so I just installed the 16 cells right out of the box and charged at 56V until one the cells started to show signs of over voltage. While the system did work and get us through the entire power outage the next day, the cells were severely out of balance and it took a couple of weeks of "screwing around" by manually connecting ceramic resistors to over charged cells and trying to individually charge low cells with a 3.6V buck charger. Should have just taken the cells out of the cabinet, put them on a bench and done what Will said.
Right now , i'm using your methode. 4 pieces 120 Ah , 3.2 V. Start charging 05/11 afternoon European Time. Four days later , Finally the end is near. i think tonight the job is done. Thank you for learning this way of topbalancing. Perfect explained . The second time i gonna place the cells first in parallel and charge up to 90%.
Hi Will, nice vid! Only one small advice: connect the batteries like you did but connect the power supply diagonal. In other words, put one of the wires on the right side of the pack. If done so the current goes thru as many busbars for each cell. Like you did, the current has to travel via ALL busbars for the right cel while the left cell gets it direct from the charger. I know, if you leave this setup stand for a while it will balance eventually but it can be done a little quicker the diagonal way.
@@finnskellig7422 Simple,just connect the + wire (from the power supply) at one end of the 16 cells, 16P, and the -- wire to the OTHER end; the way he did it makes no sense, it's a beginner mistake; The difference here, with a SMALL power supply, is negligible; BUT it CANNOT be tolerated on large (100 Amperes +) power supplies/chargers!
There are many conflicting theories about this subject including the long bus bars on battery rack units and I would agree in principle, however, if the resistance of the bus material is negligible, I would assume the current to be equally distributed across the array. Having said so, I would prefer to individually charge each battery up to its max capacity before installation but then again I'm no expert in this area (yet 😍). Thanks for your input 🙏
Came here to say this. Makes an even bigger difference if using smaller temporary wires instead of bus bars. The current can choose to go through a battery instead of toward the next battery, so by forcing the current to go all the way down the line to get back to the power supply, the delta V across each cell is much closer during the whole process, without relying as much on sitting for a while at the end.
Great advice. I would like to add something I learned. Lower quality cells can drift from one another by time (ex :when not in use) . If they are too far apart for your bms to cope with this, then I charge the individual cells (that have a lower state of charge) little by little with a 3.65v charger. They don't need to be super balanced at the end. Just enough so your bms can do the job again. Hopefully Mr Prowse agrees with this. It works for me with older sinopoly batteries from my boat, that sometimes sit idle for 6 months
Hi Henri. Do you put a load directly on a cell that is too high? And charge the low cells as you said. I have a boat and need to do this now. André in Sydney
One note that, while not too important once the current drops to a low level, to properly balance the voltage of the pack is to connect one charging lead to the right side and the other charging lead to the left side. This is to balance out the resistance in the length of the wires and buss bars. Otherwise the last cell in the string of parallel batteries may be at a slightly lower state of charge from receiving less current from a higher resistance. Connecting one on the left and another to the right balances this all out
That sounds pretty reasonable. Though we are talking about 1-2mm thick buss bars. Only pressure fit connections, but I can't imagine the resistance being significant - do you have any numbers of what kind of resistance this could be and the corresponding voltage drop/unbalancing?
I agree with you Jason. I used short pieces of small wire to top balance all my cells because I didn’t have enough bus bars and I measured 9mV drop in each cell as I got further away from the PS leads. It did finally all balance out once I switched the leads around like the you said but it probably took much longer than it should have.
@@gkeith4120 yes, this would be slightly better. I would connect the + on the first cell and the - on the last cell. This way the total buss bar length (+ & - together) is the same for each cell.
Great video! Thanks. I didn't realize balancing with such a simple thing it sounded complicated until this video. I had one cell that was charging higher than the others and BMS over voltage protection was making the charge bang on and off repeatedly. I took my pack apart and strap them all in parallel and they top balanced themselves in a couple hours. Now the system charges quickly and without any banging on and off. The only thing I don't understand is why the BMS didn't do this automatically. Thank you sir!
I am in the process of doing this to my 4S 280Ah setup. It takes forever. I'm past the 12 hr mark now and the batteries still take 4.4A at 3.65V. A tip to consider!! Do not place the power leads at the same end of the battery bank. The cell furthest away will not receive the same amount of charge due to the (small) voltage drop in the bus bar. Connect the leads at the opposite ends. That will give a more even charge as the current to each cell will have roughly the same length of cable/bus bar to travel through.
Hello, unfortunately I don't understand English very well but I really like how you explain things. I really like to watch your videos and learn a lot from you, for that I would like to thank you very much and I hope that you continue to shoot videos. Best regards from Vienna
Great video. We too figured you just put the new cells in and the bms takes care of everything. We bought 8 cells to replace bad 100ah ANC cells. Our sample size is 1 so we can't make any statistical judgements but we still don't recommend neata batteries, anc cells or seplos bms (doesn't balance cells well or at all). We got a black LONGWEI that otherwise looks just like Will's power supply. We only received (as expected) 8 bus bars with our 8 cells. We drilled holes in aluminum yards sticks for on-the-cheap bus bars to balance. We put an extra new battery in the group in case one of older ones doesn't charge up to 3.6. We are currently at 3.8a and 3.353V. We have 9 more 5kWh (server rack) packs so this is going to be a long process.
You might have just saved me a whole bunch of $$$ and hours!. I've spent the last two weeks testing and balancing a 13s cradle system in series. Groups of 12.
I’ve got 3,7v lion cells with 50 A.h. Cap. Didn’t get to use power source, after I’ve watched this video I wasn’t sure about the result but here it is. Connected all cells in parallel and the result over the night exactly 9hrs30 minutes. Cells differed at around 0,5 Volt before- and after the night result -> 3,551 each cell.
You should always use a blocking diode to charge batteries with a lab power supply to prevent the current from flowing back into the power supply outputs. Those power supplies usually have a crowbar circuit across the outputs that can short and cause a short circuit across the outputs. This will blow your power supply instantly.
Ian, What would be looking for in the blocking diode you suggest - assuming one of the recent 24V surplus BYD packs ( like David Poz's) using a charger like Will was using? A link would be nice🙂 Thanks
i had seen another popular broadcaster showing parallel charging & even though they've done it that way for years with lead acid I was doubtful. But now I'm not! Thank you.
Thanks for your share. A little suggestion: connect each battery by Cement resistance at first, like 2 ohm /5W. It can avoid big current to damage battery. After all battery have be balance (with same voltage), exchange the cement resistance to copper sheet, and charge / recharge one cycle.
Damn kid! You are providing such a Wonderful service to the Solar Community at large and you Clearly enjoy what you are doing. We can’t thank you enough for sharing your knowledge with us!
Just came across this video. I had eight fortune cells I ordered last year and am just getting around to putting the system together. This totally takes the mystery out of top balancing. These things are expensive and I was sweating this aspect of the build.
If your power supply has an option for sense leads you can add a second pair of leads from the power supply to the battery terminals. This lets the power supply sense the voltage at the battery and any voltage drop is eliminated. This makes the top-level charge quicker without the need to boost the voltage setting.
Thank you very important step ! Most LiFePO4 type cells I have dealt with are only charged to about 80% or so new when shipped. I like to pre test each cell first .bring up than parralo charge . takes more time but can do 4S banks get them over 90% . then let go for a day or 2 in parralo.
You should put together some videos with your knowledge and experience and give us solutions in the Sailing world. Many sail boaters want to move away from clunky diesel engines and go electric. Your videos are of great value.
All the cells will have slightly different impedance. If they are closely matched, they will stay in balance for a large number of cycles. If they are not closely matched they will drift out of balance relatively quickly. For LiFePO4 cells independent cell passive top balancing circuits will keep individual cells from overcharging and the pack BMS from prematurely shutting off or the charging circuit from thinking the pack has full charge when it doesn’t. If you’re a hobbyist and you like messing with this stuff all the time to keep it working, you don’t need the expense. However if you just want it to work and you don’t want to screw with it all the time, pay the money. I used to have a ‘66 Mustang that I was always working on and I loved it... until I got older and making more money. I ended up getting a BMW M5 and paying someone to work on it when it infrequently needed it.
I recommend you place the leads from the power supply at the opposite ends of the bank. You have both leads at the same end. The cell at the far end of the bank will not have the same voltage as the cell closest to the power supply leads. It's not that big of a deal, but it could have a measurable impact on the SOC of the cells furthest away from the power supply leads. When the positive is on the close end and the negative lead is on the far end of the bank, the electrical "path length" to each cell is much more similar. This techniques really shines when you are pulling a heavy load from the cells. Each cell is better able to deliver current equally to the load.
You're talking about needing a cell balancer every 6 months to a year. Can you discuss balancers that your recommend, and the steps needed to determine if it needs used and how to use it? What is bottom balancing? Are these balancing practices needed on pre-assembled batteries as well? You mentioned that this is kind of unnecessary and that they balance over time, correct? What's the benefits of balancing every 6 months? Thank you, Will! 🙏
by connecting the power supply to the first cell, it will be a higher voltage than the cell on the far right due to the resistance off the busbars and the connections between them. Better would be positive from charger to the left positive terminal and negative from the charger to the right negative terminal
Thanx for this brother Will. I have a 4P4S 12v battery and one of my 4P sets were at 3.7 SOC while the other three were at 3.5 so I am following your vid... Shalom
Batteries wired in parallel self balance themselves. If you hook all them up in parallel and let the batteries sit for a couple days, they will self balance without hooking up any charger to it.
Hint. . .put the Positive on one end of the battery and the Negative at the opposite end of the battery. . . . Draw it out on paper. . . . Resistance of the interconnections is balanced this way. . . Better thismway when discharging to.
Last year I bought a set of 16 LiFePO4 280AH batteries to build a 48V system. After setting idle for a year they had an initial voltage of 3.16V per cell. I used a lead acid battery charger to bring 4 sets of 4 cells up to near 3.4V per cell which is where the lead acid chargers stopped charging. I top balanced 2 sets of 4 batteries wired in parallel at 3.65V with a 30V 10A power supply set at 3.65V and 10A. The power supply is struggling to charge the 3rd & 4th sets above 3.34V with the power supply set at 3.65V. Should I turn up the voltage a few notches and keep a watch on the batteries to insure they don't rise above 3.65V?
Good evening my friend, please watch your videos and everything is very nice, continue like this .... recently I made an electric scooter and put a 72volt 80 amp controller !!! the scooter is very powerful and so I bought 24cells 3.2v 50ah lifepo4 batteries ... did I do well to buy them? I had to buy something else because my bms created a problem and I took them out of a scooter .. I think it was the best for my scooter ...
Shouldn't you be charging from a centerpoint? The small but still present resistance of the buss bars and connection points will create at least a .1 or .2 VDC difference from the charger connection point to the last battery. So the further downstream, you still have imbalance. Always appreciate your videos, thank you.
hi the positive and negative connections should be at opposite ends of the battery to more evenly charge the battery's else the ones closest to the charger will charge first and take a long time to distribute the charge to the cells further away
Does not matter here because at that current with these bus bars, current sharing is not an issue. If you are charging quickly, then it will matter and it needs to be at opposite ends.
Parallel connections should be connected with the first cell positive and last cell negative to better equalize else like the way t You had it will full charge the first cell.
Wow! I think you answered my exact question with a video! how awesome is that!? Fantastic content Will, took me from zero knowledge to acceptable moron on the subject of solar in just a few days.
So if I buy 4x 3.2V brand new cells, I can just buy a decent 4S 12V 60A (say) BMS, wire up the balance cables, and that's that? Let the BMS top balance the cells for me, then do a few discharge capacity tests? I'm slowly learning more and more about this stuff. The biggest scary part is the initial balancing - top balancing, bottom balancing, it becomes a lot of info to process. Thanks so much for your videos, I'm learning a lot!
How often should this be done with your system? Is it recommended to disassemble a 24v bank down to 12v run in parallel to ensure its balanced every couple of years?
You might wish to have the positive and negative on physically different ends of the cells so the resistance of the terminal connection is equalized the as you demonstrated the cells furthest away from the charger will have a lower voltage than the ones closest to the charger. Great production quality on your videos BTW!
You should connect the charger diagonally, so positive and negative are on opposite sides of cell block, so the current is accepted equally by all cells and voltage is truly balanced. The way you have it now the cell closer to the PSU will be charged more than cell further away from PSU. Since most people don't wait until current drops all the way to zero, this could lead to less than ideal balance.
If you're charging quickly, sure. Charging .1-10A across 150A bus bars is not going to cause a current sharing issue. If you want to do that, go for it. If we were charging quickly, current sharing is concern and it needs to be diagonal.
Just a pick at nits. I won't ever used a metal ratchet-driver without isolating one bus. I appreciate your videos and I'd like to see more so please don't replicate my error.
@@WillProwse I'll go have a watch, Thanks. Sorry for the trouble. Seems that, I'm just a little sensitive after that particular unscheduled welding event and I don't want to go shopping for underwear in the current climate.
The simplest solution is usually the right one! But I'd make note of *why* the safety glasses are needed in this case. You've got half of an arc welder sitting right there....
How does that bench power supply know when to stop charging? Or do you just need to monitor the voltage and stop it manually? It was my understanding overcharging LiFePO4 is very bad :)
Hi Will thank you so much for the information that you provide and this video. A few places that I've read on top balancing mentioned letting the pack settle for an hour or so and then check the pack voltage. Keep charging and resting the pack until the pack settles in at 3.65. Is that necessary in your opinion? Or just let the charger get to 3.65 and then reassemble the pack? Thanks again.
I’m in the process of switching from lead acid batteries to Lifepo4. I got 4 12v, 200 ah Ampere time batteries that will be connected in series and parallel for a 24 volt system. My first question is, what charger did you use? I looked on Amazon for the one you had, but couldn’t find it. My second question is, do I need a BMS with a Victron 150v, 100a charge controller? Thanks for all you do. Your tutorials enabled me to set up our off grid solar.
I always stick the red and black leads in the centre of the string of cells rather than both at one end, if you check the cell voltages they will be higher at the end nearer the leads for a good few hours. If you leave em charging for days it probably doesnt make much difference tho.
Hi Will, ..as usual, great video. I would like to know your favorite test method for determining when a cell is heading for early failure. Is measuring the rise of internal cell resistance a good method for LiFePO4 chemistry. What and how is your method...
When I saw this vid I thought wow, Will is a mind reader 🙂. Please make that video! Have a EVT4000 scooter that I converted to 48 volt Elite Power Li’s w/ active balancing 10-years ago. Has worked great all these years. But recently have been experiencing voltage sag with higher demand accelerations. Suspect a bad cell or two. Coincidently, I let pack sit for a long period & active balancing drew pack down to 20% above absolute zero capacity. Amazingly, on full recharge, pack was revived with very little sag. It appears that “full” discharge helped things allot. Is that possible? Still plan on doing the manual cell balancing you outlined on this video. Will watch for your NEXT video about diagnosing bad cells!! Thanks for your highly informative channel 👍
Like you said, you can plug 2 rows of 8 in series so you'll be charging at 28.8V. Your psu still supplies 4.35A, but your charging will be 8x faster. You can even speed up the process by setting the voltage to the max of 30V, for 7% increase in charging speed. It won't damage the cells, as they are usually rated for 4V charge voltage. You can lower the voltage, as soon as the amps drop close to zero
As always great video :) Just observation in this setup without any compression at 3.6v all this batteries will expend permanently i the middle on they sides ?
Hey Will, first off, I want to thank you for all the great videos, and for the easy to follow book too. You gave me the courage, and knowledge to get started on my first solar system. Since it’s taking a month of Sundays to top balance my EVE LF280K cells, Is there any reason I can’t charge them first with my all in one solar power system. Then re-configure them and top balance um.
I never hear of anyone discharging multiple cells in parallel. Top balancing and charging up in parallel as you show here is fine. Is there a technical issue with discharging all cells in parallel for bottom balancing? This way balance is never a problem.
Hi DIY Solar, Wouldn't Bottom Balancing be a better method? When top balancing, you measure at the steep side of the charge curve where the last 5% (or so) of the S.O.C. will be. When bottom balancing, you discharge all the cells till 2,6 (about) and will know all the cells will be at the lower 10% of their charge Connecting them in series and charge them with a normal charge current would result in an equal charge in each battery, specially when avoiding the upper 10% (90%S.O.C.) I would like to hear your reason for choosing for top balancing. Regards and keep up the good works!
I make my year balance everything when it's December. Then the sun is not showing so much and I can swap out cells and load them up. Usually I wait until the cells are at 80 to 90 soc. I have 16 cells with 105Ah as a 12V system. So if iam putting 4 cells out I have reduced capacity but I don't care. Then I load the cells single to 3.65V and take the next and so on. The last 4 cells I swap out with the remaining full loaded 12 cells. And then I can load the 4 cells up and integrate them into the battery after that. It's a little work but it pays off. Only after 1 and a half years now I get cell block 3 slightly off at 0.1V when iam at 100Ah left on the battery... I make top balancing because my battery is more time in an higher soc then at low. So due summertime I have always over 70% soc
Nice. A fortune cell balancing vid. Good thing I need to balance 8. Thanks Will you are the dude. So if I don't have a bench charger, I can make two 12v stacks and use a car charger?
Hello, thanks for explaining the procedure. I appreciate your enthusiasm. I have a small question: Is it safe to keep them charging overnight? Technically, if I keep the supply voltage to 3.6V, then it should be safe, as once all of them charged and balanced, the input current will be o eventually, right? Just wanted to confirm from you who must have been doing this often.
I never do actually. I have a lot of my habits form charging lipoly cells for years. I try to avoid charging unattended often. It shouldn't take more than a few hours if your cells are at high soc.
@@WillProwse l did not do a capacity test. I'm new to this and found out how important it is to do that. Well here's the deal I have 6- 100AH batteries on a 12,000watt growatt inverter. The system has been up and running for 2 months now. In the last week I noticed that the batteries would not charge fully as they were. They now peak at 53.3 volts. I checked the screen and the voltage is off on some of the cell's. Now of course I tried to save money like most dummies and purchased the batteries from AliExpress. Also they hold up well until they hit about 49or 50 volts and then they seem to speed up discharge. But it varies on discharge. I don't work the system hard at all but I guess the capacity test will tell all. By the way the voltage different is like 3262mv and 3293 in difference. What do you think I should do.
Hey! I love your channel and motivated me to build my own Lifepo4 battery. I’ve been having issue with the top balancing seems to be stuck at 3.26v and one cell at 3.24v currently charging at 3.65 and 5.9-6A and doesn’t seem to be going up. Been going for almost 20 hours? I’m using a cheap Amazon power supply with 14g alligator clamp? Could that be causing the issue. Thinking about going to 12awg with ring terminals. Thanks for the help!
Hi I am one of your subscribers I really like the great things you are to us.please I am from Ghana but staying Italy. I really want to talk to you for the project I want to do
2:27 for Step by step top balancing instructions
If you buy quality new cells, you can use BMS to top balance, then capacity test in a few cycles. That's the easiest way.
Ian made a great point of using a blocking diode so you won't burn up the power supply. Smart idea.
If you are quick charging, current sharing is an issue and you need to attach the positive and negative leads at opposite ends of the battery. In this video we are balancing and topping off at very low currents, so you can attach the leads anywhere. If it makes you feel better to attach at opposite ends, go for it. .1A on a 150A bus bar is not going to cause a current sharing problem.
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Does off-grid solar confuse you? Check out my DIY friendly website for solar system packages and product recommendations, and so much more! www.mobile-solarpower.com
Join our DIY solar community! #1 largest solar forum on the internet for beginners and professionals alike: www.diysolarforum.com
Check out my best-selling, beginner-friendly 12V off-grid solar book (affiliate link):
amzn.to/2Aj4dX4
If DIY is not for you, but you love solar and need an offgrid system, check out Tesla Solar. Low prices and great warranty, and they can take your entire house offgrid with their new Powerwalls: ts.la/william57509
~~~~~~~~~~~~~~~~~~~~~~~~~
My solar equipment recommendations (Constantly updated! Check here first):
12V/48V Lithium Batteries: www.mobile-solarpower.com/solar-batteries.html
Solar System Component Directory: www.mobile-solarpower.com/solarcomponents.html
Plug-N-Play Systems: www.mobile-solarpower.com/full-size-systems.html
Complete 48V System Kits: www.mobile-solarpower.com/complete-48v-solar-kits.html
DIY Friendly Air Conditioner/ Heat Pumps: www.mobile-solarpower.com/solar-friendly-air-conditioners.html
Complete 48V System Blueprint: www.mobile-solarpower.com/48v-complete-system-blueprint.html
~~~~~~~~~~~~~~~~~~~~~~~~~~
My Favorite Online Stores for DIY Solar and Coupon Codes:
-Current Connected: SOK, Victron and High Quality Components. Best prices and warranty around: currentconnected.com/?ref=wp
-Signature Solar: Cheap Server Rack Batteries and Large Solar Panels:
www.signaturesolar.com/?ref=h-cvbzfahsek
-Ecoflow Delta Official Site: My favorite plug-n-play solar generator:
us.ecoflow.com/?aff=7
-AmpereTime: Cheapest 12V batteries around:
amperetime.com/products/ampere-time-12v-100ah-lithium-lifepo4-battery?ref=h-cvbzfahsek
-Rich Solar: Mega site and cheaper prices than renogy! Check them out:
richsolar.com/?ref=h-cvbzfahsek
-Shop Solar Kits: Huge site with every solar kit you can imagine! Check it out:
shopsolarkits.com/?ref=will-p
-Battery Hookup: Cheap cell deals
bit.ly/2mIxSqt
10% off code: diysolar
-Watts 24/7: Best deals on all-in-one solar power systems, with customer support and distribution here in the USA:
watts247.com/?wpam_id=3
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Contact Information:
I am NOT available for personal solar system consult! If you wish to contact me, this is my direct email: williamprowsediysolar@gmail.com
Join the forum at diysolarforum.com/ if you wish to hang out with myself and others and talk about solar
FTC Disclosure Statement and Disclaimers:
Every video includes some form of paid promotion or sponsorship. Some links on this youtube channel may be affiliate links. We may get paid if you buy something or take an action after clicking one of these. My videos are for educational purposes only. Information is subject to change/update at any time. Electricity is DANGEROUS and can kill. Be smart and use common sense :)
DIY Solar Power with Will Prowse is a participant in the Amazon Services LLC Associates Program,
An affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com
Can I do this top balancing at a higher amperage, say 3.6V @50A?
DIY Solar Power with Will Prowse Do you ever resale any of the cells you test?
Wanting to build a battery for a small camper project. Just thought I’d ask. And thanks for all the info in your videos.
@@tevincampbell1735 Sure as long as you don't exceed the c rate of the battery
Hello is it okay to top balance cell 4 cell, parallel 2 cell at a time ? and another 2 after, because i only have 3 busbar but i need atleast 6 busbar to parallel all 4 cell at the same time. thanks
@@BlazeByte21 I would think you could balance 2 pairs and then balace the two balanced pairs. But Iif I read your question correctly, you'd eventually have to connect all 4 to balance them equally. You need 6 busbars to do that. If you have some copper pipe you can make great busbars with a hacksaw, a hammer, and a drill for the lug holes. Cut the pipe into the correct length, ,smash the pipe flat with the hammer, and drill the correct spaced and sized holes. You don't have to have commercial busbars.......
Bruh!! Largely because of you and what I learned from watching many of your videos, my family had a battery backup for fridges and fans in place after hurricane Milton. (Multiple 24v battery packs of 3.2 lifepo4 batteries, with BMSs, on a GroWatt inverter.) Thankfully our power came back up before I needed to pull out the 4 400w solar panels to start to recharge. …man was I proud to have that in place for me and my family.
Thank you sir!!
Finally, a clear, concise, rational explanation. Tons of half-assed information on TH-cam.
Anyone building a DIY battery pack should follow these instructions. The last 48V battery I put together a couple of months ago was needed for a scheduled neighborhood transformer replacement power outage and unfortunately the Chinese prismatic cells did not get delivered until late the day before. Fortunately I had the cabinet, buss bars, wiring, BMS & cell balance board ready to go so I just installed the 16 cells right out of the box and charged at 56V until one the cells started to show signs of over voltage. While the system did work and get us through the entire power outage the next day, the cells were severely out of balance and it took a couple of weeks of "screwing around" by manually connecting ceramic resistors to over charged cells and trying to individually charge low cells with a 3.6V buck charger. Should have just taken the cells out of the cabinet, put them on a bench and done what Will said.
Right now , i'm using your methode. 4 pieces 120 Ah , 3.2 V. Start charging 05/11 afternoon European Time. Four days later , Finally the end is near. i think tonight the job is done. Thank you for learning this way of topbalancing. Perfect explained . The second time i gonna place the cells first in parallel and charge up to 90%.
Hi Will, nice vid! Only one small advice: connect the batteries like you did but connect the power supply diagonal. In other words, put one of the wires on the right side of the pack. If done so the current goes thru as many busbars for each cell. Like you did, the current has to travel via ALL busbars for the right cel while the left cell gets it direct from the charger. I know, if you leave this setup stand for a while it will balance eventually but it can be done a little quicker the diagonal way.
Hi Rik, any chance you could elaborate a bit more on how to do this please? cheers
@@finnskellig7422 Simple,just connect the + wire (from the power supply) at one end of the 16 cells, 16P, and the -- wire to the OTHER end; the way he did it makes no sense, it's a beginner mistake;
The difference here, with a SMALL power supply, is negligible; BUT it CANNOT be tolerated on large (100 Amperes +) power supplies/chargers!
There are many conflicting theories about this subject including the long bus bars on battery rack units and I would agree in principle, however, if the resistance of the bus material is negligible, I would assume the current to be equally distributed across the array. Having said so, I would prefer to individually charge each battery up to its max capacity before installation but then again I'm no expert in this area (yet 😍). Thanks for your input 🙏
Came here to say this. Makes an even bigger difference if using smaller temporary wires instead of bus bars. The current can choose to go through a battery instead of toward the next battery, so by forcing the current to go all the way down the line to get back to the power supply, the delta V across each cell is much closer during the whole process, without relying as much on sitting for a while at the end.
If you do supply few amps (and the rated capacity is way way bigger) and dont have extremely flimsy busbars, it doesn't matter.
This should be the first video anyone watches before building a battery bank. Wish I'd seen it much sooner!
Great advice. I would like to add something I learned. Lower quality cells can drift from one another by time (ex :when not in use) . If they are too far apart for your bms to cope with this, then I charge the individual cells (that have a lower state of charge) little by little with a 3.65v charger. They don't need to be super balanced at the end. Just enough so your bms can do the job again. Hopefully Mr Prowse agrees with this. It works for me with older sinopoly batteries from my boat, that sometimes sit idle for 6 months
Hi Henri. Do you put a load directly on a cell that is too high? And charge the low cells as you said. I have a boat and need to do this now. André in Sydney
One note that, while not too important once the current drops to a low level, to properly balance the voltage of the pack is to connect one charging lead to the right side and the other charging lead to the left side. This is to balance out the resistance in the length of the wires and buss bars. Otherwise the last cell in the string of parallel batteries may be at a slightly lower state of charge from receiving less current from a higher resistance. Connecting one on the left and another to the right balances this all out
That sounds pretty reasonable. Though we are talking about 1-2mm thick buss bars. Only pressure fit connections, but I can't imagine the resistance being significant - do you have any numbers of what kind of resistance this could be and the corresponding voltage drop/unbalancing?
I agree with you Jason. I used short pieces of small wire to top balance all my cells because I didn’t have enough bus bars and I measured 9mV drop in each cell as I got further away from the PS leads. It did finally all balance out once I switched the leads around like the you said but it probably took much longer than it should have.
Would it make more sense during parallel topping off to put connection both on center cell?
@@gkeith4120 yes, this would be slightly better. I would connect the + on the first cell and the - on the last cell. This way the total buss bar length (+ & - together) is the same for each cell.
Great video! Thanks. I didn't realize balancing with such a simple thing it sounded complicated until this video. I had one cell that was charging higher than the others and BMS over voltage protection was making the charge bang on and off repeatedly. I took my pack apart and strap them all in parallel and they top balanced themselves in a couple hours. Now the system charges quickly and without any banging on and off. The only thing I don't understand is why the BMS didn't do this automatically. Thank you sir!
Fantastic video. A proper initial balance will ensure the longest life and best capacity. I can’t wait to see you build a system with those cells.
I am in the process of doing this to my 4S 280Ah setup. It takes forever. I'm past the 12 hr mark now and the batteries still take 4.4A at 3.65V.
A tip to consider!!
Do not place the power leads at the same end of the battery bank. The cell furthest away will not receive the same amount of charge due to the (small) voltage drop in the bus bar. Connect the leads at the opposite ends. That will give a more even charge as the current to each cell will have roughly the same length of cable/bus bar to travel through.
Funny. I just noticed another post saying the same thing.
Hello, unfortunately I don't understand English very well but I really like how you explain things. I really like to watch your videos and learn a lot from you, for that I would like to thank you very much and I hope that you continue to shoot videos. Best regards from Vienna
Great video. We too figured you just put the new cells in and the bms takes care of everything. We bought 8 cells to replace bad 100ah ANC cells. Our sample size is 1 so we can't make any statistical judgements but we still don't recommend neata batteries, anc cells or seplos bms (doesn't balance cells well or at all). We got a black LONGWEI that otherwise looks just like Will's power supply. We only received (as expected) 8 bus bars with our 8 cells. We drilled holes in aluminum yards sticks for on-the-cheap bus bars to balance. We put an extra new battery in the group in case one of older ones doesn't charge up to 3.6. We are currently at 3.8a and 3.353V. We have 9 more 5kWh (server rack) packs so this is going to be a long process.
You might have just saved me a whole bunch of $$$ and hours!. I've spent the last two weeks testing and balancing a 13s cradle system in series. Groups of 12.
I’ve got 3,7v lion cells with 50 A.h. Cap. Didn’t get to use power source, after I’ve watched this video I wasn’t sure about the result but here it is. Connected all cells in parallel and the result over the night exactly 9hrs30 minutes. Cells differed at around 0,5 Volt before- and after the night result -> 3,551 each cell.
I just wanted to tell you that I'm learning so much about solar components from you and your videos. Thanks and keep those videos coming.
You should always use a blocking diode to charge batteries with a lab power supply to prevent the current from flowing back into the power supply outputs. Those power supplies usually have a crowbar circuit across the outputs that can short and cause a short circuit across the outputs. This will blow your power supply instantly.
Oh that's smart!!!! Will add that. Good point
Only needed on the + side?
Be sure and take the voltage drop across the blocking diode and subtract from your metered voltage.
Ian,
What would be looking for in the blocking diode you suggest - assuming one of the recent 24V surplus BYD packs ( like David Poz's) using a charger like Will was using? A link would be nice🙂
Thanks
What size/type it should be ?
i had seen another popular broadcaster showing parallel charging & even though they've done it that way for years with lead acid I was doubtful. But now I'm not! Thank you.
Thanks for your share. A little suggestion: connect each battery by Cement resistance at first, like 2 ohm /5W. It can avoid big current to damage battery. After all battery have be balance (with same voltage), exchange the cement resistance to copper sheet, and charge / recharge one cycle.
Damn kid!
You are providing such a Wonderful service to the Solar Community at large and you Clearly enjoy what you are doing.
We can’t thank you enough for sharing your knowledge with us!
Just came across this video. I had eight fortune cells I ordered last year and am just getting around to putting the system together. This totally takes the mystery out of top balancing. These things are expensive and I was sweating this aspect of the build.
I've been having this problem, one of my cells run away at high voltage. I'm gonna take my bank apart again, and top balance. Thanks Will...
Did you manage to solve the problem?
If your power supply has an option for sense leads you can add a second pair of leads from the power supply to the battery terminals. This lets the power supply sense the voltage at the battery and any voltage drop is eliminated. This makes the top-level charge quicker without the need to boost the voltage setting.
Thank you very important step ! Most LiFePO4 type cells I have dealt with are only charged to about 80% or so new when shipped. I like to pre test each cell first .bring up than parralo charge . takes more time but can do 4S banks get them over 90% . then let go for a day or 2 in parralo.
Manual top balance, gold nuggets, thanks! Been watching your videos since before you got an RV! Now look at you!
Thanks Will. The charge profiles confirm that numbers I came up with recently after days of testing and checking sources for my own build...
You should put together some videos with your knowledge and experience and give us solutions in the Sailing world. Many sail boaters want to move away from clunky diesel engines and go electric. Your videos are of great value.
I referenced this vid on Off Grid Garage's current (Jul 2021) discussion of balancing.
Keep the good info coming!
The lifepo4 battery i build for my ebike lost the balancing, thanks for the video , i will top charge each serial line of the battery
Nicely done, thank you for doing this video! Straight to the point, accurate, and very helpful for those looking to put together packs.
Will thanks for keeping it simple. I just received my 271ah cells and will apply this method to top balancing them.
You just keep coming with these tutorials! Wow!
All the cells will have slightly different impedance. If they are closely matched, they will stay in balance for a large number of cycles. If they are not closely matched they will drift out of balance relatively quickly. For LiFePO4 cells independent cell passive top balancing circuits will keep individual cells from overcharging and the pack BMS from prematurely shutting off or the charging circuit from thinking the pack has full charge when it doesn’t. If you’re a hobbyist and you like messing with this stuff all the time to keep it working, you don’t need the expense. However if you just want it to work and you don’t want to screw with it all the time, pay the money.
I used to have a ‘66 Mustang that I was always working on and I loved it... until I got older and making more money. I ended up getting a BMW M5 and paying someone to work on it when it infrequently needed it.
I recommend you place the leads from the power supply at the opposite ends of the bank. You have both leads at the same end. The cell at the far end of the bank will not have the same voltage as the cell closest to the power supply leads. It's not that big of a deal, but it could have a measurable impact on the SOC of the cells furthest away from the power supply leads.
When the positive is on the close end and the negative lead is on the far end of the bank, the electrical "path length" to each cell is much more similar. This techniques really shines when you are pulling a heavy load from the cells. Each cell is better able to deliver current equally to the load.
You're talking about needing a cell balancer every 6 months to a year. Can you discuss balancers that your recommend, and the steps needed to determine if it needs used and how to use it?
What is bottom balancing?
Are these balancing practices needed on pre-assembled batteries as well?
You mentioned that this is kind of unnecessary and that they balance over time, correct? What's the benefits of balancing every 6 months?
Thank you, Will! 🙏
Using the same power supply today as is in the video lol. It's great!
by connecting the power supply to the first cell, it will be a higher voltage than the cell on the far right due to the resistance off the busbars and the connections between them. Better would be positive from charger to the left positive terminal and negative from the charger to the right negative terminal
Thanx for this brother Will. I have a 4P4S 12v battery and one of my 4P sets were at 3.7 SOC while the other three were at 3.5 so I am following your vid...
Shalom
Always learn more when I watch your videos! Thanks, J
Batteries wired in parallel self balance themselves. If you hook all them up in parallel and let the batteries sit for a couple days, they will self balance without hooking up any charger to it.
Will, l think your a great teacher-Solar Guru🇦🇺
Thats alot of money for your vids. All these lifep04 batteries🙌🏽
as usual, first rate work! clear, to the point and smart science!
Thanks Will. Great tips. Thanks for your insight.
best solar channel by far, thanks
Fantastic, thank you for taking the time to explain this process, Will!
Thanks Will for giving us interesting and informative uploads. You make lockdown easier. 👍
Great info and timing for my project, appreciate it Will.
Hint. . .put the Positive on one end of the battery and the Negative at the opposite end of the battery. . . . Draw it out on paper. . . . Resistance of the interconnections is balanced this way. . . Better thismway when discharging to.
Did you not read my pinned comment. Current sharing is not an issue when pushing .1-4 amps across 150A bus bars. Attach it wherever you please.
Last year I bought a set of 16 LiFePO4 280AH batteries to build a 48V system. After setting idle for a year they had an initial voltage of 3.16V per cell. I used a lead acid battery charger to bring 4 sets of 4 cells up to near 3.4V per cell which is where the lead acid chargers stopped charging. I top balanced 2 sets of 4 batteries wired in parallel at 3.65V with a 30V 10A power supply set at 3.65V and 10A. The power supply is struggling to charge the 3rd & 4th sets above 3.34V with the power supply set at 3.65V. Should I turn up the voltage a few notches and keep a watch on the batteries to insure they don't rise above 3.65V?
Oh thank you so mucu, your information is gold!
Good evening my friend, please watch your videos and everything is very nice, continue like this .... recently I made an electric scooter and put a 72volt 80 amp controller !!! the scooter is very powerful and so I bought 24cells 3.2v 50ah lifepo4 batteries ... did I do well to buy them? I had to buy something else because my bms created a problem and I took them out of a scooter .. I think it was the best for my scooter ...
Always nice to be around this cude dude ;)
Shouldn't you be charging from a centerpoint? The small but still present resistance of the buss bars and connection points will create at least a .1 or .2 VDC difference from the charger connection point to the last battery. So the further downstream, you still have imbalance. Always appreciate your videos, thank you.
hi the positive and negative connections should be at opposite ends of the battery to more evenly charge the battery's else the ones closest to the charger will charge first and take a long time to distribute the charge to the cells further away
Does not matter here because at that current with these bus bars, current sharing is not an issue. If you are charging quickly, then it will matter and it needs to be at opposite ends.
.1-10 amps on this size of bank, with pure copper bus bars that can handle 150A, the resistance is minimal.
@@WillProwse Thanks for clearing that up.
Thanks for a concise video Will, thanks for not wasting our time with 11 minute BS if there is no need for it
Parallel connections should be connected with the first cell positive and last cell negative to better equalize else like the way t
You had it will full charge the first cell.
Wow! I think you answered my exact question with a video! how awesome is that!? Fantastic content Will, took me from zero knowledge to acceptable moron on the subject of solar in just a few days.
So if I buy 4x 3.2V brand new cells, I can just buy a decent 4S 12V 60A (say) BMS, wire up the balance cables, and that's that? Let the BMS top balance the cells for me, then do a few discharge capacity tests? I'm slowly learning more and more about this stuff. The biggest scary part is the initial balancing - top balancing, bottom balancing, it becomes a lot of info to process. Thanks so much for your videos, I'm learning a lot!
Will Power, Inc. Top global producer of solar and lithium products.. Nice ring to it. What do you think?
Jack Frick sounds like an antipodean NASCAR driver to me ;)
Another great video Will!
should the battery pack be compressed during the balancing period?
How often should this be done with your system? Is it recommended to disassemble a 24v bank down to 12v run in parallel to ensure its balanced every couple of years?
You might wish to have the positive and negative on physically different ends of the cells so the resistance of the terminal connection is equalized the as you demonstrated the cells furthest away from the charger will have a lower voltage than the ones closest to the charger. Great production quality on your videos BTW!
th-cam.com/video/k-V8RIuyBbU/w-d-xo.html
How do u buy ur battery on Ali express. I have problems communicating with them. I need a good buyer
You should connect the charger diagonally, so positive and negative are on opposite sides of cell block, so the current is accepted equally by all cells and voltage is truly balanced. The way you have it now the cell closer to the PSU will be charged more than cell further away from PSU. Since most people don't wait until current drops all the way to zero, this could lead to less than ideal balance.
Did you see my pinned comment
If you're charging quickly, sure. Charging .1-10A across 150A bus bars is not going to cause a current sharing issue. If you want to do that, go for it. If we were charging quickly, current sharing is concern and it needs to be diagonal.
@@WillProwse Doh, sorry I did not see it :-(
Just a pick at nits. I won't ever used a metal ratchet-driver without isolating one bus.
I appreciate your videos and I'd like to see more so please don't replicate my error.
That is a insulated ratchet. That's why I use that. It's composite. This was covered in previous videos as well.
@@WillProwse I'll go have a watch, Thanks.
Sorry for the trouble. Seems that, I'm just a little sensitive after that particular unscheduled welding event and I don't want to go shopping for underwear in the current climate.
The simplest solution is usually the right one! But I'd make note of *why* the safety glasses are needed in this case. You've got half of an arc welder sitting right there....
How does that bench power supply know when to stop charging? Or do you just need to monitor the voltage and stop it manually? It was my understanding overcharging LiFePO4 is very bad :)
Hi Will thank you so much for the information that you provide and this video. A few places that I've read on top balancing mentioned letting the pack settle for an hour or so and then check the pack voltage. Keep charging and resting the pack until the pack settles in at 3.65. Is that necessary in your opinion? Or just let the charger get to 3.65 and then reassemble the pack? Thanks again.
I’m in the process of switching from lead acid batteries to Lifepo4. I got 4 12v, 200 ah Ampere time batteries that will be connected in series and parallel for a 24 volt system.
My first question is, what charger did you use? I looked on Amazon for the one you had, but couldn’t find it.
My second question is, do I need a BMS with a Victron 150v, 100a charge controller?
Thanks for all you do. Your tutorials enabled me to set up our off grid solar.
I always stick the red and black leads in the centre of the string of cells rather than both at one end, if you check the cell voltages they will be higher at the end nearer the leads for a good few hours. If you leave em charging for days it probably doesnt make much difference tho.
Lots of people say charge them up to 3.6. I have never managed to charge my 105ah ones past the point of 3.4v before my BMS cuts them off.
Great video! But what kind of charger should I use to balance to 3.6v?
Hi Will, ..as usual, great video. I would like to know your favorite test method for determining when a cell is heading for early failure. Is measuring the rise of internal cell resistance a good method for LiFePO4 chemistry. What and how is your method...
Good question. Should make a video on this
When I saw this vid I thought wow, Will is a mind reader 🙂. Please make that video!
Have a EVT4000 scooter that I converted to 48 volt Elite Power Li’s w/ active balancing 10-years ago. Has worked great all these years. But recently have been experiencing voltage sag with higher demand accelerations. Suspect a bad cell or two. Coincidently, I let pack sit for a long period & active balancing drew pack down to 20% above absolute zero capacity. Amazingly, on full recharge, pack was revived with very little sag. It appears that “full” discharge helped things allot. Is that possible?
Still plan on doing the manual cell balancing you outlined on this video. Will watch for your NEXT video about diagnosing bad cells!! Thanks for your highly informative channel 👍
Thanks, looking forward to your video on this often overlooked test.
Like you said, you can plug 2 rows of 8 in series so you'll be charging at 28.8V. Your psu still supplies 4.35A, but your charging will be 8x faster.
You can even speed up the process by setting the voltage to the max of 30V, for 7% increase in charging speed. It won't damage the cells, as they are usually rated for 4V charge voltage. You can lower the voltage, as soon as the amps drop close to zero
Always great videos/information....and great eye candy :)
Man i loved this video, thank you
As always great video :)
Just observation in this setup without any compression at 3.6v all this batteries will expend permanently i the middle on they sides ?
Hey Will, first off, I want to thank you for all the great videos, and for the easy to follow book too. You gave me the courage, and knowledge to get started on my first solar system.
Since it’s taking a month of Sundays to top balance my EVE LF280K cells, Is there any reason I can’t charge them first with my all in one solar power system. Then re-configure them and top balance um.
Thanks for sharing Will. May I know why we have used 16 LFP cells to make 48V pack instead 15?
My palms are sweating when I see your hands waving above the terminals.
another question - - - can you use a good 12 volt car charger to bring up 4 sells in series before charging all the batteries in parallel
I never hear of anyone discharging multiple cells in parallel. Top balancing and charging up in parallel as you show here is fine. Is there a technical issue with discharging all cells in parallel for bottom balancing? This way balance is never a problem.
👍Great precise basic information! Thank you!
Thank you for the video. At what Nm should those prismatic cells be tightened?
Hi DIY Solar,
Wouldn't Bottom Balancing be a better method?
When top balancing, you measure at the steep side of the charge curve where the last 5% (or so) of the S.O.C. will be.
When bottom balancing, you discharge all the cells till 2,6 (about) and will know all the cells will be at the lower 10% of their charge
Connecting them in series and charge them with a normal charge current would result in an equal charge in each battery, specially when avoiding the upper 10% (90%S.O.C.)
I would like to hear your reason for choosing for top balancing.
Regards and keep up the good works!
Good info.
I make my year balance everything when it's December. Then the sun is not showing so much and I can swap out cells and load them up. Usually I wait until the cells are at 80 to 90 soc.
I have 16 cells with 105Ah as a 12V system.
So if iam putting 4 cells out I have reduced capacity but I don't care. Then I load the cells single to 3.65V and take the next and so on.
The last 4 cells I swap out with the remaining full loaded 12 cells. And then I can load the 4 cells up and integrate them into the battery after that.
It's a little work but it pays off. Only after 1 and a half years now I get cell block 3 slightly off at 0.1V when iam at 100Ah left on the battery...
I make top balancing because my battery is more time in an higher soc then at low. So due summertime I have always over 70% soc
Thanks Wil
I would also connect the plus to the left and minus at the Right site.
Did you see pinned comment
Aliexpress does not have these, please advise on where to purchase these batteries!
Great job on the vids Will I grabbed your book too!
Nice. A fortune cell balancing vid. Good thing I need to balance 8. Thanks Will you are the dude. So if I don't have a bench charger, I can make two 12v stacks and use a car charger?
Hello, thanks for explaining the procedure. I appreciate your enthusiasm. I have a small question:
Is it safe to keep them charging overnight? Technically, if I keep the supply voltage to 3.6V, then it should be safe, as once all of them charged and balanced, the input current will be o eventually, right? Just wanted to confirm from you who must have been doing this often.
I never do actually. I have a lot of my habits form charging lipoly cells for years. I try to avoid charging unattended often.
It shouldn't take more than a few hours if your cells are at high soc.
@@WillProwse Got it! Thanks :)
What do you do if you buy a pre-assembled battery from a manufacturer and the cells are not balanced in a 48v server rack battery.
Cycle it. It will balance over time. Is it pulling full capacity?
@@WillProwse l did not do a capacity test. I'm new to this and found out how important it is to do that. Well here's the deal I have 6- 100AH batteries on a 12,000watt growatt inverter. The system has been up and running for 2 months now. In the last week I noticed that the batteries would not charge fully as they were. They now peak at 53.3 volts. I checked the screen and the voltage is off on some of the cell's. Now of course I tried to save money like most dummies and purchased the batteries from AliExpress. Also they hold up well until they hit about 49or 50 volts and then they seem to speed up discharge. But it varies on discharge. I don't work the system hard at all but I guess the capacity test will tell all. By the way the voltage different is like 3262mv and 3293 in difference. What do you think I should do.
Hey! I love your channel and motivated me to build my own Lifepo4 battery. I’ve been having issue with the top balancing seems to be stuck at 3.26v and one cell at 3.24v currently charging at 3.65 and 5.9-6A and doesn’t seem to be going up. Been going for almost 20 hours? I’m using a cheap Amazon power supply with 14g alligator clamp? Could that be causing the issue. Thinking about going to 12awg with ring terminals. Thanks for the help!
for optimum charging You should put one charging port on the oposite side of the cell pack
No need at all. Did you see pinned comment
.1 amps will not have current carrying issue on a 150A busbar
Awesome Video!
Hi I am one of your subscribers I really like the great things you are to us.please I am from Ghana but staying Italy. I really want to talk to you for the project I want to do
Him - "You can't screw this up" Me - "Hold my beer"