6s battery charging cell voltage fluctuation

ESK8 Electronics
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#1

Hi, Newb here, please excuse some ignorance… Two-3s batteries in series that I’m charging; all cells show on the imax B6 charger, cell 3 and 4 are fluctuating as its charging and I’m not sure why? There doesn’t appear to be any consistency; one second all the cells will show similar voltage, the next cell 3 will show zero and cell 4 maxes out. It’ll show this real quick and then jump back to all 6 showing similar voltage. In regular charge mode the charger usually stops after a few seconds and I assume its because cell 4 hits ~5v(as in the picture) and the summation of all the cells reaches the cutoff V ceiling. In balance mode it usually makes it a little farther along the charge process, though as in the picture, cell 3 is lagging a bit. Has anyone seen this or anything I can do to try and resolve or are these cells cooked somehow? I typically only charge in ‘Balance mode’ thinking that’s the safer approach given the inconsistency.

Batteries = Zippy Capacity: 5000mAh, Voltage: 3S1P / 3 Cell / 11.1v, Discharge: 20C Constant / 30C Burst

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#2

It looks more like a charger issue than Battery issue. I don’t care how old or dead a battery is I don’t think it could ever go 3.7v to 0v in a split second unless you dropped it in salty water. Is than Ann original imax or a clone? Do you have any other means of charging too check on the battery

#3

I’ve seen it once but it happened immediately after the balance connector was plugged in. The problem was a bad wiring. It might be a different issue since it looked ok before you charged it.

2 Likes
#4

Do you have a voltmeter so you can check the individual cell voltage from the balance lead. Can you charge each 3s separate? Also it is possible you have one bad cell. However the 0 and 5v readings aren’t correct either. I’d check each cell prior to charging then charge each separate. Then see what happens

#5

Little embarrassed but yeah, seemed to be the wiring. I soldered together my balance lead’s JST connectors so I could charge the two 3s batteries simultaneously, seems my middle balance lead cable (4th) wasn’t a strong connection at all (I gave them all a little tug and that one easily separated.) That would account for the wonkiness on the 3rd and 4th cell I think.

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Seems to be charging correctly now. Thanks so much.

To anyone else that reads these post, might be worth buying a 2x-3s to 6s adapter instead of trying to solder everything yourself.

1 Like
#6

Nothing to be embarrassed about. Enjoy the ride.

#7

Hi, I have a 12s setup with bms and a common scooter 3 prong charging port hooked up to it I am not sure what’s the issue but when I power up the esc it works great but it discharges quick in my opinion then I hook the charger to it and it charges the battery to quickly also. Not sure if only 1 of the 6s battery is working but I don’t know why this is happening. Could it be that I have a defective battery?