I bought an AGM universal 35amp battery at my local auto parts store ( UB12350 )

It's been great and as an AGM battery there is minimal leakage worries when we are on out ear

Also being AGM I can run them down and not worry about lifespan issues

:: I also use a motorcycle battery from Sears, works great
:: and lasts quite awhile even with occasional night use
:: using running lights.
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:: :: I'm not an electrical expert, I use two garden tractor
:: :: size 12 v batteries- 5"x7"x6"high. I assume to get
:: :: lighter I could use one smaller battery- What size and
:: :: spec does any one use just to run speed/depth instuments
:: :: for the day