charging issue?

[mr72]

thanks for that, Pete. Yeah the stator and the reg/rect are both putting out the right voltage. It just turns out the LiFePO4 can handle more charge voltage and get a little higher charge compared with what the GS puts out by spec.

No big deal. Just need to deal with the care and feeding of the LiFePO4.

Doubt I'll ever have to use it when it's cold enough to affect it, but I did also know about the "turn on the light for a minute first' thing. Thanks for the reminder.

[peteGS]

Good stuff, figured it's better to repeat something you already know rather than miss something that could be helpful.

[mr72]

Good stuff, figured it's better to repeat something you already know rather than miss something that could be helpful.

I couldn't agree more.

And FWIW your input was quite timely.

I am learning about some of the idiosyncrasies of this LiFePO4 battery. This particular battery is like 10% of the size and weight of the original lead-acid battery, and the capacity is also much less. Not 1/10 but more like 1/4. I think this is relevant because there seems to be a threshold for how much it gets "cold" and how much you have to "warm it up" as it relates to the battery's capacity and the current requirement of the starter.

I think if you get an 8ah LiFePO4 (same capacity as the stock battery) then it probably only takes a few seconds of running the lights before the starter will turn over, and only when it's REAL COLD will it require you to run the lights for like a minute or two to "wake up" the battery. However, with a 2ah or so battery like this one, combined with LED lights which draw much less current, then even when it's 60F it seems I have to turn on the key/lights for like 15-20 seconds before it will turn the starter. If it's 40F I might have to run the lights for a minute or more. My guess is I'd have to run the lights for like 5 minutes before it'd start if it was 30F.

The reason this is interesting and worth note is because it sounds and feels like a charging problem. You get on the bike and ride, say, from your house to the gas station. Turn off the bike and pump gas, then you probably already have your helmet and gloves on so you proceed to turn the key to on and immediately try to start, it will just click. You go "what the heck?", fool with it, do the normal "is this going to work?" kind of stuff all while the lights are on and then after like 20-30 seconds it magically starts right up. If you didn't keep the lights on for that 30 seconds and try again, you'd likely think (as I did) that the battery didn't charge from the start from your house to the gas station.

TL;DR: You have to have a startup routine with these small LiFePO4 batteries wherein you deliberately wake up the battery every time no matter how cold it is outside or how long since the bike was shut off. At 70F ambient temperatures, it still requires this wake-up routine. Otherwise it may behave like it has a charging problem when it is actually charging correctly.

[peteGS]

Good to know! Being told about that and experiencing it are two different things. It really doesn't get that cold here (lucky if it gets to single digit celcius in the middle of winter) so I suspect I won't have quite the same issues but the instinct would definitely be oh no something is wrong!