I have VERY strong opinions about batteries and their care.
I'm sure everyone's experience is similar - my boating life has been blighted by other boater's batteries letting them/me/everyone down at the water's edge/middle of the sea
Old batteries, fcuked batteries, ex-car batteries, flat batteries, loose batteries*
God help me, I've even driven down slips and jump started ribs with my 110
. I even pack a spare battery in the back when meeting other boaters for big days out. "OH, my battery is shot, erm...."
Whatever you do - get a decent battery
/combo/switch and keep 'em in good nick - they're your friends, be NICE to them
* OK, that one might have been mine