Allison Xb 21

[jpowell]

I’m thinking about buying a new 300 r engine. Is anyone running lithium cranking battery’s if so which ones should I buy.

[BlueallyXB21]

I am using the Ionic 125AH. My son is using the same, We both are running 300R engines. No issues at all.

[fishnfireman]

IMO---just be sure it has an updated BMS that won't shut power to the engine.
Ionic is one who has done testing with the Merc V8's

[CPA Basser]

I would not use a lithium cranking battery while the engine is still under warranty, at a minimum.