Not sure of the size, but I have had one in my Cruzer for a couple years. So far, no issues cranking my Lycoming O-235. I would recommend getting the battery box they sell. It made installation a snap.
I have two ETX680C lithium battery in my Zenith CH-750 Cruzer, never a problum,
I highly recommend a OptiMATE Lithium 4s 9.5A TM-275 Battery Charger with Select & TUNE ECU Flash, you can work on your plane with the power switch turn-on with out pulling on the battery, Also a standard battery car charger will not top-off the battery's.
(If you forget to turn off the master power switch ((pilots never forget to do that, LOL)) it will not kill the battery, it has a auto-off function to prevent from damaging the battery.
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