When I was initially looking for a Monster to purchase I looked at a 900 that a guy had tricked up a bit and he was running a battery out of a Skidoo/snow mobile. It had a shitload of cranking power and he'd never had a problem with charging. (He said??) Dunno what brand it was though. Being designed to supply current and amps in very cold weather you would think it would be operating easily at "normal" temps. Hmmmmmmmmm.
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Yep it would work well at normal temps but also would probably be better built internally as well to stand up to the physical pounding it would get. Boat batteries are the same.
It's worth purchasing a cheapo multimeter for those "dead battery" times, you can see if the batteries dead or your charging system is working ok. Saves $$$ in the long run.
If anybody needs assistance or has questions,in this, I can help, (I'm an electrical\electronics dude)