[UPDATE] Battery not charging after discharging to 0% - Fixed!

Hey, Everyone! So, I went for an afternoon ride today and ended up completely discharging my battery due to heavy winds on a route that would normally leave me with 30% or more battery left.

When I got home to charge the battery, the charger LED remains green and does not initiate charging. I checked the charger and the battery (showed 34.1V) with a multimeter, and power seems to still be flowing.

When I turn on the board while plugged in, the battery indicator rises to 100%, and falls rapidly to 0% when I unplug the charger. Could there be something wrong with the BMS or a battery cell group?

Is there anything further I can do to diagnose or fix this problem? Thank you!

Battery: 10s6p Samsung 30Q pack with a BMS assembled by @psychotiller


100% is because its reading the power putting out from the charger, it won’t charge because you drained it to much.

The only way to charge it know is to charge it bypassing the BMS

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Okay, thanks!

Is it safe?

Yes it’s safe. You are still at 3.4v/cell which is well above the safe discharge voltage.


Okay. So I need some help with bypassing the BMS. Do I just charge with wire coming directly from the charging port to the positive and negative ends of the battery pack?

0% would be below 25V on your pack. I discharge mine till 2,8V per cell without issues. So it looks like it’s just below your bms setting maybe or your charger makes some crazy stuff.


Check the voltage out of the charger


The plus of the charger to the plus of your pack The minus of your charger to the minus of your pack


It’s reading 42V

Okay. I did just that and it’s still not charging

And if it’s below?

Must be a bad BMS you need to take the negative lead from battery before the BMS and then attach that to the negative of the charger

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Hmmm, my negative lead from my battery goes straight to the negative of the charger. I have already cut all wires coming from the negative of the battery pack to the BMS.

One of your parallel connections in the battery is bad then. Send it back to @psychotiller for repair.


Alright. Thanks for all of your help!

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If it’s below 2.5V per cell it’s a problem.

Shouldn’t the charger non the less charge? :thinking: I mean it’s a simple charger not a balance charger. This charger see only measure the input voltage not the cell count or anything else. Even if a cell in the p group is bad (or one connection is bad) the over all voltage of the pack is still 34 something volt, which should be enough to make the charger charge. No?

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I guess. The only other recommendation I would have would would be to check the individual P group voltages and make sure they are all the same.

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