I can’t see the link for some reason and the imperial measurements don’t compute for me
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I can’t see any notable corrosion there… have you checked the individual cell voltages through the balance connector?
Check them, write them down and share them here
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I have not checked the individual cells yet only the p groups.
it’s 12.7mm by 1.6mm and it will be 610mm long on each side.
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That sounds perfect dude
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have you checked the individual cell voltages through the balance connector?
Is there any way to check the voltage of cells in parallel without taking them out of the the group? I cannot think of one. This is a 10s3p battery…
thanks
Thats a very small amount of corrosion and I wouldn’t be too concerned about it.
You should be able to clean that up with a bit of isopropyl.
My bet is that your pack is out of balance for any number of reasons and that may be the cause of your problems
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Yes, I did check all the balance leads, both before and after I removed the bms. All p-groups are at 4.1 or 4.09.
The next test I was going to do is to attach a small restive load, and see if the p-groups become out of balance.
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That’s a good plan. Was the bms wired for discharge or charge only?
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Both. Do any prebuilts come discharge only?
The vast majority of prebuilt boards come wired for discharge and charge.
It definitely sounds like something is triggering your bms to cut off the power, but with all of your cells balanced reasonably well, its gonna be a little trickier to determine exactly where.
Installing an LLT will assist you greatly in monitoring all the cells while under load so that you can identify any problems
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After around a 10 second load at 4a the p-groups range from 4.07v to 4.09v.
A second draw a few minutes later for another 20 or 30 seconds gave a maximum difference of 0.03v while under load. I cannot draw any longer than that without burning my biggest heat sinked resistor.
The groups on the negative side are always 0.01-0.03v lower. Other than that it seems fine. The groups all recovered to 4.05v and 4.06v.
What do you all think?
I think you really need to watch the individual voltages during the testing but gut feeling says that the original bms is just fucked.
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Hopefully your right. I’ll be able to see all the voltages at once once I wire the smart bms.
The battery pack did start acting up not long after installing a vesc. Perhaps I drew too much. I had it set to 25a.
That’s the first time I’m seeing paper wrapped Li-ion cells wtf
They’re like coin rolls. Don’t see them much these days but a lot of the older batteries outta china used to use them
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Hi guys, just need your advice. I have a battery pack that’s 16s7p, I was riding for like around 60km’s when I got cut off but the pack voltage has not reached the cut off voltage set. Around 5-7 volts more i think.
When I checked the BMS app, cell 1 reached it’s cut off.
Now I got home and tried charging cell 1 to the same voltage (different balancer) as the rest and try to charge all of them but cell 1 is charging behind. Around 0.02v behind from the rest of the group.
The pack is fairly new with 17 cycles. Any idea what’s wrong before I remove cell one and check individual cells? Just need some insights first before I do that. Will try to ride again after I fully charge this and monitor. Any advice on what to watch out while riding?