Left my board powered on for over a week, cells discharged to < 2.5V/cell

So even though I haven’t had a chance to really ride my new lilFOCer v3.1 from @makerspev yet, I somehow managed to leave it on in storage for at least a week. This was something I feared would happen since I got my original rig working. It looks like the cells went way below the recommended minimum of 3.1V per. The board would not turn on at all when I first recognized what had happened. When I connected a charger, I was able to power up shortly after and app read 38-39V after it first booted up. I checked the Voltage Cutoff End setting and it was set to 37V or around 2.5V per cell.

So I have two questions.

  1. Is this pack now unsafe? I brought it back up to around 50V and it rides fine. I understand my cells have for sure been damaged and at best capacity will be diminished. But I will swap it and dispose of the bad pack if it is dangerous. No BMS so I assume I should at least nee to hook it up to an FM BMS and balance it. Is there a risk of breaking solders in the array from cells swelling when this happens?

  2. What does the Balance App/General Shutdown Mode setting do? I see it is set to OFF_AFTER_30M but that does not seem to work. What would be required to implement an auto shutoff after 15 or 30 minutes of inactivity? Would be nice to have for dummies like me :slight_smile:

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The only solution is to go as fast as possible on it before it blows.

Hold your breath, charge it up. Prepare to find the local hazmat house if it turns sour.

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If it didn’t go much below 2.5V then you’re probably fine, I’d slowly charge it, obviously not in sub 50F temps - if you don’t have a BMS with temp sensor then you could monitor the battery temps by hand, it shouldn’t warm up at all if charged at 3A or less. Batteries don’t just explode from a cold state, if you notice them getting warm then I’d avoid riding the pack. Otherwise I’d continue using it.

But this is just my opinion, not official advice :slight_smile:


For the Future Motion boards It’s programmed into the Smart BMS, the feature that turns the board off. Will automatically shut off after 15min no use. Would be cool to have that feature but needs to be implemented into a BMS. If you still got a FMXR board to check the battery on, you could swap the battery over to check the cells. That was my original plan til I fried my FM BMS on the board I was going to use to swap and check. You didn’t mention what battery you are using either. I’d just run it cautiously at first, have not heard of anyones battery blowing up from running no BMS. Even the ZBMS that’s coming out will not let you monitor cells via app ect. The ennoid offers cell monitoring but difficult to setup from what I hear.