SHELBY GT 350 Member
Joined: Jan 2011
Location: Central Massachusetts
I don't think you really need/want a deep cycle battery, they are made/intended for applications like boat trolling motors where the battery is deeply discharged slowly and then slowly recharged . . . in a car it is not like that, you have a fairly demanding but short power draw when you start the car, and then a quick recharge when the car is running.
If you do want to go the deep cycle route, you could go to Walmart; find the correct battery for your car (look it up in the little computer they have there) and then carry it over to the deep cycle marine batteries, and find the one that is the closest match. Most marine batteries are dual purpose deep cycle / starting these days, so that might actually be a pretty good choice.
You can kill a deep cycle battery by leaving it discharged just like any other battery. They should be kept charged just the same.
Simpler solution is to just buy a new battery when they die. I've decided I will always buy my batteries from Walmart from now on -- they seem to be cheaper and last just as long as the "better" batteries you can buy elsewhere for more money.
To keep the battery from dying during long periods when you don't drive the car, put it on a battery tender or charge it periodically.
| 2010 GT coupe | Daily Driver with some Steeda and GT500 take-off stuff for the occasional track day