[Fr. Frank]

I guess I'm the oddball in this. I use two very large lead-acid Group 31M batteries. 1150 CA, 970 CCA, 180 minute reserve capacity. 13"L x6.8"W x9.5"H, 57 lbs. I buy blemished Interstate batteries from the distributor for about $50 each (retail $147), and I average about 4 years battery life using a computerized variable amperage battery maintainer. Truthfully, I expect 2-3 years of life, but I think the battery maintainer really keeps them fairly sulfate-free.

I've had one premature battery "failure" in the last 12 years, and during the initial charging, it literally exploded about 10 minutes after the charger was plugged in. It sounded like a hand-grenade going off next to the house. (The battery was not in the boat or in the garage, but outside next to my trash cans just in case that precise event were to occur). As it threw acid all over the charger, too, I'm still unsure as to whether it was a battery failure or charger failure.

The downside is that blemished battteries come with no warranty.

I also use a blermished Group 31 for my 15 kW diesel generator, which 27 hp single cylinder 2-stroke diesel motor requires 650 CA just to spin.