battery size?

[elwopo]

I have twin 1998 Mercury 200 efi engines. Twin batteries already, but it might be a good idea to have a spare starter battery stashed.
What would you suggest as the right "size" to get, and do I look only at cca?
Don't want to get one too small to crank if necessary.

 

[Laddies]

Re: battery size?

Min. 450cca. Remember you can never have to big pf a battery if you need it in a emergency.