P
I'm on my third lithium Ion battery and I can say with some confidence that they have limitations. I started with a Li-Ion on my Nytro, and as crazy as it sounds the 800 Etec is harder to start than an 3 cylinder Nytro at any given temperature.
I could trust my Li-Ion to start my Nytro down to -10 celcius, no problem. My Summit would be half of that -5C. I could probably spend 15 minutes cycling the battery to get the Summit to go in colder temps, but not going there....too hard on the starter/electrical system.
Basically I use the Li-ion in spring conditions when its warm or any situation where the battery will stay warm...like day drives.
I use the biggest Shorai LFX36L3-BS12, which is the biggest possible and almost the same size as the stocker battery.
OTM
What he said -- had the same experience with the Snowbike as well as Yamaha sleds on Lithium Ion Batteries