Ant BMS not picking up every cell?

Quinc

1 kW
Joined
Apr 18, 2016
Messages
314
20S Ant bms, I have tried 2 different apps, unplugging and plugging back in, reseting via the app, taking off the lead wires and putting them back but cannot get it to show me the correct cell voltages. (All cells are between 3.83-3.85) I can also read all of the correct cells from the bms wire harness with volt meter. Any ideas or did I get a bad bms?

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My experience is with JBD smart BMS units, but that 30 volts might be just leakage through the FETs since they're turned off, thinking some of the cell groups are too low of a voltage. If you're sure the cells all have proper voltage, then it seems like that 20s BMS isn't configured properly somehow.

EDIT: also double check your wiring by putting the black meter probe on the black balance wire, then the red voltage probe on balance wire 1. Should be 3.6 volts, 2 should be 7.2 volts, ect all the way through till the red wire is 72 volts.
 
thundercamel said:
My experience is with JBD smart BMS units, but that 30 volts might be just leakage through the FETs since they're turned off, thinking some of the cell groups are too low of a voltage. If you're sure the cells all have proper voltage, then it seems like that 20s BMS isn't configured properly somehow.

EDIT: also double check your wiring by putting the black meter probe on the black balance wire, then the red voltage probe on balance wire 1. Should be 3.6 volts, 2 should be 7.2 volts, ect all the way through till the red wire is 72 volts.

Thank you! Took all the wires off and put them back on and now its good. Next question is does the ant auto balance feature work and how long does it take. :)
 
Quinc said:
Thank you! Took all the wires off and put them back on and now its good.

That's why quality connectors are usually gold plated. Things like this happen much less often.

That multi-meter. :lol: Harbor Freight used to give them away free with any purchase. Buy a roll of electric tape for 99 cents, you get that multu-meter for free. I would not use around things that can explode or set your house on fire.
 
On mine, it will balance during charging once the cell voltage are above the balance threshold, say 4.0 volts. It does this by draining the high groups through resistors until they match the lowest group. I can also switch modes to make it keep balancing even when not on the charger, but it will stop once it reaches the balance threshold, which I have set to 4.0 volts. It's useful to do when I first build a pack, but after I calibrate the voltage readings for each group in the BMS with a higher precision meter.
 
The auto-balance function on mine (build 2020) stops when the charging current gets lower then 0.3A.
Your can also start balancing manually without charging, then it balances as long as it takes to equalize all cells.
 
Been using the battery/bms now a few times but it is showing the battery dead after using only 6.8ah out of the 16ah and 66v out of the 84. Is that normal? Any suggestions on my settings? I took the screenshot when I got home from the lake and it now shows 12% but a few hours before that it was showing 2%.

Also is there a way to see what the peak amps where during use?

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I'd say it looks like normal behavior, and the reading of 6.8 amp hours used is possibly incorrect. The cells do recover a bit of voltage after sitting, which is why the estimated 2% remaining climbed to 12%. You could get some more info by adding one of these power meters to your setup.
 
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