addisonk Posted July 13, 2022 Share Posted July 13, 2022 Hi, Anyone know where I can source 120Ah 3.2v LiFePO4 cells? Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted July 13, 2022 Share Posted July 13, 2022 2 hours ago, addisonk said: Hi, Anyone know where I can source 120Ah 3.2v LiFePO4 cells? Thesunpays but the price has gone up quite a bit. Quote Link to comment Share on other sites More sharing options...
addisonk Posted July 14, 2022 Author Share Posted July 14, 2022 14 hours ago, Scorp007 said: Thesunpays but the price has gone up quite a bit. They dont have stock. These things seem to be scarce as hen's teeth with all the loddshedding. I am desperate as I need to repair an LBSA battery and they have not been much help. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted July 14, 2022 Share Posted July 14, 2022 3 hours ago, addisonk said: They dont have stock. These things seem to be scarce as hen's teeth with all the loddshedding. I am desperate as I need to repair an LBSA battery and they have not been much help. I understand they don't sell to the public but to installers. Electromann also no stock but you can try them. Not aware of any sellers. Anyone on bidorbuy perhaps? Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted July 14, 2022 Share Posted July 14, 2022 (edited) 3 hours ago, addisonk said: Double post Edited July 14, 2022 by Scorp007 Quote Link to comment Share on other sites More sharing options...
iiznh Posted July 18, 2022 Share Posted July 18, 2022 On 2022/07/14 at 10:54 AM, addisonk said: am desperate as I need to repair an LBSA battery and they have not been much help. I also have a LBSA DIY battery. It sucks that they were keen to get your business and now they have turned around and will not give you any backup. www.e-glow.co.za imports cells too, but they sell out very fast What is wrong with your battery? What happened? Quote Link to comment Share on other sites More sharing options...
addisonk Posted July 18, 2022 Author Share Posted July 18, 2022 3 hours ago, iiznh said: I also have a LBSA DIY battery. It sucks that they were keen to get your business and now they have turned around and will not give you any backup. www.e-glow.co.za imports cells too, but they sell out very fast What is wrong with your battery? What happened? I bought a built 6kwh unit from LBSA as a reseller. It worked well for the first 3 months and after that had endless problems on and off. Sent it up to Joburg for a warranty repair and it came back with what seems to be the same fault. They want me to send it back for the second time but shipping from Cape Town to Joburg and back costs around R1200.00 not to mention the labour to uninstall, package and re-install, inconvenience etc. I know that one of the cells is faulty but they've refused to provide me with a replacement part to repair it locally. They insist on it being sent back to them which is will cost another R1200.00 and is totally impractical. They told me that if we repair it ourseves then will void the warranty but I'm not too concerned about that as the warranty is worth nothing if it costs a fortune to return for repairs. My advice is that unless you live within close proximity of the LBSA factory then dont buy one. I certainly wont be doing so again. Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted July 18, 2022 Share Posted July 18, 2022 11 minutes ago, addisonk said: I bought a built 6kwh unit from LBSA as a reseller. It worked well for the first 3 months and after that had endless problems on and off. Sent it up to Joburg for a warranty repair and it came back with what seems to be the same fault. They want me to send it back for the second time but shipping from Cape Town to Joburg and back costs around R1200.00 not to mention the labour to uninstall, package and re-install, inconvenience etc. I know that one of the cells is faulty but they've refused to provide me with a replacement part to repair it locally. They insist on it being sent back to them which is will cost another R1200.00 and is totally impractical. They told me that if we repair it ourseves then will void the warranty but I'm not too concerned about that as the warranty is worth nothing if it costs a fortune to return for repairs. My advice is that unless you live within close proximity of the LBSA factory then dont buy one. I certainly wont be doing so again. I have the same issue with them, and I have the archived data to prove it. They told me exactly the same, bring the battery to them and they will look in to it. that would mean myself having to travel +_ 220 KM return trip leave the battery there for +_ 2 days and travel another 220 Km to fetch back, not even considering the expense of getting my installer to come disconnect/connect the battery. And with load shedding on a daily basis been without power for about 4 hours a day. see dashboard bellow cell number 8 does not reach full charge. Quote Link to comment Share on other sites More sharing options...
iiznh Posted July 18, 2022 Share Posted July 18, 2022 13 minutes ago, Antonio de Sa said: cell number 8 does not reach full charge Does cell 8 get depleted first? If this cell has more capacity than the rest it will not reach the top voltage. My battery pack does that too, I also have some cells reaching 3.55V and others still on 3.4V but I am getting more than the promised 10KWh. What matters is that you get the full stated capacity from your battery. If you charge it showly at 5-10A you can balance the cells nicely over a couple of days. It needs to charge at a low current to enable the pack to top balance The Cell voltages is simply an indication of how well top balanced the pack is. Steve87 1 Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted July 18, 2022 Share Posted July 18, 2022 3 minutes ago, iiznh said: Does cell 8 get depleted first? If this cell has more capacity than the rest it will not reach the top voltage. My battery pack does that too, I also have some cells reaching 3.55V and others still on 3.4V but I am getting more than the promised 10KWh. What matters is that you get the full stated capacity from your battery. If you charge it showly at 5-10A you can balance the cells nicely over a couple of days. It needs to charge at a low current to enable the pack to top balance The Cell voltages is simply an indication of how well top balanced the pack is. @iiznh yes, it does, check dashboard, it's very seldom that I discharge my battery bellow 40% however, there was an instance that I dropped bellow 10% SOC, there it is. Most definitely cell number 8 has a problem. Quote Link to comment Share on other sites More sharing options...
iiznh Posted July 18, 2022 Share Posted July 18, 2022 9 minutes ago, Antonio de Sa said: Most definitely cell number 8 has a problem. Cell 8 seems is unbalanced with the rest of the pack, that does not say it is a problem cell. Have you top balanced your pack? Charge it to 95%, then charge it from grid slowly with 5A till you see cell 8 rise to 3.55V, it will give the pack some time to top balance and will allow more energy to get into cell 8, this might take a couple of days depending on how big the mismatch is. The Daly BMS only balance cells while there is a charge voltage and current is flowing. If it is properly balanced cell 8 charges slower than the rest then I would say it is not well matched to the rest of the battery pack. If you charge the cells with high currents or never fully charge the pack and give it time to top balance, cells tend to drift Sorry I bought DIY cells for the exact reason that I want to be able to self-service the pack, they have performed well even though some times of the day I hit them with plenty current, once the shade hits my panels then the remaining 5A works nicely to balance the cells Quote Link to comment Share on other sites More sharing options...
addisonk Posted July 18, 2022 Author Share Posted July 18, 2022 In my case its cell 2 that is the problem. What happens is after about 15 minutes cell 2 voltage drops to about 2.8v and I see a current spike of 72 amps on the logs. The SOC then drops down to about 10%. I suspect there may be another cell thats on its way out but I will first replace C2 and then monitor the battery and see how it responds. Quote Link to comment Share on other sites More sharing options...
iiznh Posted July 18, 2022 Share Posted July 18, 2022 The voltage of a cell shows a complete different picture when being charge and discharged. If you are not prepared to top balance the pack, no amount of swapping the cells will fix your problem. The only voltage relevant is 3.47 - 3.6V when charging with a low current that indicates a cell is fully charged. Any other voltage means it still needs current. If a cell is not well matched to the rest of the pack you will struggle with it, swapping it with another random cell bought online will most likely give the same results. So I'm starting to understand why they cannot simply send you replacement parts. Quote Link to comment Share on other sites More sharing options...
addisonk Posted July 18, 2022 Author Share Posted July 18, 2022 7 minutes ago, iiznh said: The voltage of a cell shows a complete different picture when being charge and discharged. If you are not prepared to top balance the pack, no amount of swapping the cells will fix your problem. The only voltage relevant is 3.47 - 3.6V when charging with a low current that indicates a cell is fully charged. Any other voltage means it still needs current. If a cell is not well matched to the rest of the pack you will struggle with it, swapping it with another random cell bought online will most likely give the same results. So I'm starting to understand why they cannot simply send you replacement parts. Agreed. Top balancing is essential as well as using good quality cells. Quote Link to comment Share on other sites More sharing options...
addisonk Posted July 18, 2022 Author Share Posted July 18, 2022 27 minutes ago, iiznh said: The voltage of a cell shows a complete different picture when being charge and discharged. If you are not prepared to top balance the pack, no amount of swapping the cells will fix your problem. The only voltage relevant is 3.47 - 3.6V when charging with a low current that indicates a cell is fully charged. Any other voltage means it still needs current. If a cell is not well matched to the rest of the pack you will struggle with it, swapping it with another random cell bought online will most likely give the same results. So I'm starting to understand why they cannot simply send you replacement parts. This what mine looks like after replacing C2. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted July 22, 2022 Share Posted July 22, 2022 (edited) @stok As you are an experienced person I would like to know if you have come across the following. A 4S battery is charged from a constant voltage source. The bank was at a level where I expected the BMS to start balancing. About 30min later the battery showed a voltage higher than the constant charger voltage that was still connected. Would it be correct to assume that this increase above the supply voltage is due to the BMS balancing? Edited July 22, 2022 by Scorp007 Quote Link to comment Share on other sites More sharing options...
P1000 Posted July 22, 2022 Share Posted July 22, 2022 29 minutes ago, stok said: when activated they put a bleed resistor in series with the cell to increase that cells resistance so that it accepts charge at a lower rate than the other cells while charging, I don't even know how that would work. What they do is they put a resistor in parallel with the highest cell so some current bypasses the cell and it charges at a lower rate. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted July 22, 2022 Share Posted July 22, 2022 47 minutes ago, stok said: No, I assume its a passive balancer that you are talking about, when activated they put a bleed resistor in series with the cell to increase that cells resistance so that it accepts charge at a lower rate than the other cells while charging, when you disconnect the charger(or the BMS reaches high voltage disconnect state) that resistor bleeds the cell until it is at the set voltage and then opens to remove the resistor from the circuit again, passive BMS balancing in a nutshell. active balancing is much more simpler, it takes a charge from a high cell stores it in a capacitor and discharges the capacitor into the low cell, they are usually triggered by a set difference in voltage eg. 100mV. I would rather think that a high amp charge was somehow forced at the set voltage, and after removing the charger the cells showed some voltage rise above the set charger voltage as the chemistry inside the cells was still settling right after the charger was removed, do not quote me on this thumb suck theory of mine Thanks for the reply. Some make sense. The 100Ah left in 12V bank was charging at a low 3A from charger when this took place. I was driving so I could not stop to check. It was being charged by my car alternator at a fixed 14.2V. A voltmeter connected on the car battery and a 2nd one on the battery. I have no idea what BMS is used inside the battery. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted July 22, 2022 Share Posted July 22, 2022 41 minutes ago, stok said: do you have a dc to dc converter between alternator and battery? alternators are notorious for not playing nice with lithium No. Yes that is the short story. If you have had a voltmeter in the car for 10yrs you know what the readings are. Works great for the non smart alternators. Smart ones you have to use DC-DC converter due to the low normal voltage. Further with trail and error you can adjust the length of you cables very nicely to not have a high current. In my case with 1m x 16mm for each polarity the current to a 50% SOC was just over 30A. By adding 2m by 6sq mm per polarity the current is never over 18A. Very happy at that level and clamp meter also in view to check. Works great while driving to work and back. Quote Link to comment Share on other sites More sharing options...
P1000 Posted July 22, 2022 Share Posted July 22, 2022 2 hours ago, stok said: resistors in parallel reduce the overall resistance ( 1/rt= 1/r1+1/r2) thus it will allow more current to flow to the cell. resistor in series increase the resistance (rt+ r1 +r2) Draw a schematic, and think about current flow a bit. You cannot put a resistor in series with a cell while still keeping all the cells connected in series. Tim003 and Leondavibe 2 Quote Link to comment Share on other sites More sharing options...
P1000 Posted July 23, 2022 Share Posted July 23, 2022 (edited) 39 minutes ago, stok said: the whole passive balancing circuit is a parallel network that connects a resistor in series with the internal resistance of each individual cell. You can see the mosfet is acting as a switch that puts the resistor (or in this case 2 resistors) in parallel with the cell. Perhaps this circuit makes it clearer (left is passive, right is active): Edited July 23, 2022 by P1000 Leondavibe, BritishRacingGreen, Tim003 and 1 other 4 Quote Link to comment Share on other sites More sharing options...
JdR Posted September 14, 2022 Share Posted September 14, 2022 On 2022/07/13 at 5:33 PM, addisonk said: Hi, Anyone know where I can source 120Ah 3.2v LiFePO4 cells? Not sure if you still need them, but I have 8 x 120Ah cells (includes 24V/120A LBSA BMS). R9.5k. Quote Link to comment Share on other sites More sharing options...
addisonk Posted September 15, 2022 Author Share Posted September 15, 2022 Hi, Thanks, I already found some. JdR 1 Quote Link to comment Share on other sites More sharing options...
iiznh Posted September 16, 2022 Share Posted September 16, 2022 20 hours ago, addisonk said: Thanks, I already found some. Please do tell where you found some cells I should maybe just add, over the last month I was able to fix most of my mismatched voltages on my cells by simply tweaking the bolts. I looked at the BMS and the proceeded to add a little bit of torque to the bolts of the cells reading high (when charging with 60A). My battery is much better behaved and the voltages are much closer. I do not think the cells are necessarily bad, they are just making 100% contact. Quote Link to comment Share on other sites More sharing options...
addisonk Posted September 16, 2022 Author Share Posted September 16, 2022 I got some batteries from a guy called Neil in Thornton. PM me for his number. I ended up replacing 4 cells out of the 16. I did a capacity test on each of them and they were defintely way below what they should have been. iiznh 1 Quote Link to comment Share on other sites More sharing options...
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