What would yall say is a good size starting battery? I know my Scag ztr mower (26 briggs) has a 325 ca battery. But it doesn't run lights and a bildge either. My 4-wheeler 500 cc has one about the same size. I guess its
better to have to much juice than not enough.

I got an Optima red top in mine

If you don't use electric trim all the time, start and stop a whole bunch or use lights alot, you don't need much. I ran a 375cca garden tractor battery in the summer time on my 36, they are like $29.

I have run a 425ca lawn tractor battery since getting my PD. And that's using running lights, HH light and interior lights on a regular basis with no problems.

You really need at least 850 CCA for these motors.. While a smaller 375 CCA battery might work in the summer time once the frigid temps of LA kick in during the season you won't come close to turning that high powered mower over.. Don't even confuse these powerheads with your ZTR mower motor..