It's not a dead thread. I'm just now getting around to putting a LiFePO4 in the glovebox of the Acura.
The lithium ion battery I tried had too much initial voltage after being charged to full (16v) and was frying the LED balancing on my Ultracap bank, which in turn caused them to go out of balance and over-voltage. Apparently it didn't like going low to the 13v of the alternator, so the battery swelled and went crazy out of balance (probably a fire hazard).
Back to the LiFePO4. I always make the mistake of running the battery too low while I tinker with things or measure loads of various things, so I harmed it to some degree, though balance charging seems to have largely recovered it (slightly puffed, then went back to normal, and voltages are in balance).
I ended up buying a $10 balance circuit from Amazon that forgoes any of the other BMS functions. Of course, whatever connector it has is slightly smaller than the balance connector on the battery, so I've got to build an adaptor. In theory it harvests over voltage (threshold 0.1v and feeds it into the undervoltage cell, and then goes into low power sleep.
Next I need to see if this circuit can handle ultracaps. From some of the reviews it sounds like it might fry itself. I'd rather connect something like this to a cap bank than build a diode/LED circuit for every cap.
Amazon
