Battery issues not fully charging

Hi guys. I have an Evolve carbon gt. The battery pack failed along with motors and I smashed remote to bits about 10 times bailing at 25mph haha. As a result I bought stock motors and a remote from evolve but decided to build a 10s6p battery pack. I’ve seen it done with no issues on various forums. But… as always mine never works straight away haha. I bought genuine Samsung 30q batteries. Pure Nickel strips all welded in pyramid style across cells to not loose amps etc. All battery cables from bms are correctly soldered. It works 100% fine. Pulls like a train. My issue is that when charging it only will charge to 38v? So I’m not getting any extra from my battery pack. I’m using the stock Evolve charger. So when board dies I charge it and it charges up and seems to do its thing. Light on charger goes red then green when “charged” bit its not getting up to 42v or near? Any thing I’m missing here? I know builders who have done this and run it straight of the evolve bms with zero issues? My plan for future is building my own but for now just want extra distance and not having wasted time money and effort into building a battery that’s gaining me no extra benefit. All and any help is appreciated. Much love guys :peace_symbol::heart_decoration::om:

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I would change the bms since that seems to be the issue in this case. Does the charger turn green after 38v? If so, then one of your p group is at 42v. I’d recommend checking which one and see if you can equally discharge it to fit the rest of the pack.

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Thanks for the response. I was going to change bms and possibly even the esc if need be. Yes my charger turns green when it hits 38v. I will check each cell pack and see if there are differences as you say. So if one cell hits 42v does the charger then think its fully charged? I have each cell wired to the bms. I thought that balanced it out? But if the bms is not happy then I guess that could do it. Before I built the battery I married up the cell voltages per parallel pack. From memory all cells were reading very close when they were built. I will definitely check the cells and if one is high am I able to drain that one cell without disconnecting the other cells? I hope this makes sense? Thank you for your help. Its appreciated :peace_symbol::heart_decoration::om:

What happens is that when you charge, one p group may have a bad cell or bad weld, which will cause it to charge to 4.2V faster than the rest. The BMS will see this group hit 4.2V while the rest are still at 3.75V and stop charging to protect the pack. The charger will see that there is no more current draw and the light will turn green.

What you need to do is charge up the pack, then measure the voltage of each P-group. Find the group that has a higher voltage than the rest and inspect it. You will probably need to take it apart and swap out that p-group. (or just swap out the bad cell/fix the bad connection)

There is most likely a problem with your battery. If there is problem like a bad cell or bad weld, the BMS will not be able to balance that out. It can only balance out minor differences in the chemistry of each group.

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Thanks JoeyZ5. This makes sense. As all individual battery cells are new and are quality cells I’m hoping it may be a single 18650 that’s gone down or as you said one of my welds or solder is all worth checking. One question which I didn’t mention and I don’t see why it would make a difference but I have 8 p packs within the deck and the remaining two external as as everyone knows you cannot get a 10s6p in that deck without serious mods so I have a water proof enclosure mounted over rear truck. Only the two p packs are in there with 8 gauge cabling so shouldn’t loose ampage over the short distance. Again the bms cables are connected to these also. The bms and esc are still in original place. I don’t see this being an issue but stranger things have happened haha. Again thanks for the help. It’s all appreciated as I’m getting less miles out of a 10s6p than I am the stock evolve :exploding_head:. Haha.:peace_symbol::heart_decoration::om:

I just took board off charge and it thinks its done. Checked the remote for cell voltages and this is what it’s reading. I know this might be inaccurate due to the battery not being the evolve one and its not syncing properly maybe? P pack 2 is down by 2v on the rest and this I can see as an issue but not one of the cells allegedly have hit 42v according to the remote. I’ll check with a multimeter to get an accurate measurement.

I do recommend the multimeter. If the voltage of all cells are all 38v, then you will need to change the bms to a 10s one. Daly is a good purchase. And I use it in bypass. Usually it’s a p group error if the bms is a 10s one.