I had my winch battery out yesterday,deep cycle marine,got to thinking.Would a big deep cycle battery be a go choice for a car without an alternator. 810cca at 32degees, 7X13inchs.Wouldn't the fact that it is just a big battery be a positive?
Yes and no. Because you are still starting your car D/C isnt the best. But then since you are cycling the battery deeply because you dont have an alternaotr, it would work good for that.
Sounds like you have either a group 27 or 31 battery. Both of which you can get in a cross sort of mix between deep cycling and starting. Trojan's Superior Cycling Series is an example. This is possible because of the size of the battery.