Originally Posted by ridetheblock
Thanks for that info - I'll measure the Goose juice next time I start it. That wasn't the issue with this battery though - I installed the battery, started the bike, let it run maybe a minute, then shut it off. Then it sat in the garage a week or two - when I went to start it the next time to go for a ride - nothing. Voltage at 10.X. That bike didn't run long enough for a weak or even zero charging voltage to be the issue on the battery charge. And like I said, zero drain with key off according to my trusty Fluke.
Ok .. good to know you've got a Fluke to measure voltage with. if you've measured parasitic drain .. how many milliamps? if there was little to no parasitic drain and you started with charged LFX27 of 13.3v (90%) .. if that battery went dead on it's own in two weeks .. it's a dud
a good LiFePO4 battery will easily hold it's charge for a year .. LiFePO4 has extremely low self discharge. to find out if your Shorai has a BMS .. charge to full or 14.6v .. then allow to rest overnight .. resting voltage will be 14.25 range without BMS .. 13.85v range with BMS .. cell balancing works by shunting off excess voltage after cell full, allowing weaker cells to recover. that's the short version of how BMS works .. detailed version in LiFePO4 testing thread.