Originally Posted by Joe Houle
If you are cranking with the Shorai, and cranking becomes progressively faster/stronger with each attempt, you are not letting the battery warm up long enough initially. This is discussed on their site. I know it's counter intuitive, but try leaving the lights on longer. 3-5min. 15sec just ain't going to do it. Experiment with it to dial in your "routine". I actually turn my bike on before I even touch any gear or do my walk around.
The site actually states 15 secs if its a little cold, IIRC those slightly cold temps are still much colder than what it actually is around me. And 5-10mins if its freezing out. With my previous battery that's what i was doing (leaving the lights on for about 5mins) but the result is the same.
Also I don't think its the charging cause as stated it starts fine after a ride. Or even if its been sitting overnight but gets started in the afternoon instead of morning.