Help! Battery fully charged but low warning and no power

[Charliefox]

My Bafang 36V rear hub conversion fine for the last few years......then one flashing light on the handle bar controller....low battery and no power for the throttle. A couple of times the removal and reinsertion of the power lead to the battery had it up and running, all 4 leds lit! Enough to head back home since I was unwilling to drop the 430' feet downhill to town and the possibilty of having to push it back 6 miles uphill!
I checked out the euro plug wiring connections, bent the connecting pins slightly to get a tighter fit. Seemed OK so next day tried again. Another half mile and back to one flashing light. Both of the batteries, though 7 years old, are holding 41v after a charge. They usually give at least 20 miles and are LiFePo4 type.
I am working through checking connections but have found nothing amiss as yet.
Anyone else had a false low battery signal...and no power? Suggestions what might cause it?

 

[matthewslack]

LiFePO4 is 3.65V per cell at full charge I think, so is your 41V an overcharged 11S, which should be 40.15, or a rather low 12S, which ought to be 43.8?

If the latter, then perhaps there is a balance issue, with one cell being very low and the others OK. Can you get at the balance connector or the cell terminals to test?

 

[saneagle]

41V for LiFEPO4 battery indicates fully charged. Yes, you can charge them higher, but there is virtually no increase in charge over 41v, even though you can get the voltage higher.

LiFePO4 batteries don't wear out like normal ones.

Your problem must be a connection fault. You have to find it. You need to tell us what sort of battery it is or show a picture. If it has a key-switch, that's where I'd be looking first.

 

[Nealh]

36v LFP is 12s so typically 3.40/3.45v is the max one needs to charge them per cell group , as d8veh has said pretty pointless charging them higher.