24 volts starter batteries , What size from experience?

Hi all, I was starting to go through the process of changing to onboard starter and batteries, Hemi 526 and 168 tooth flexplate with a CSR starter, but being in a altered room is tight.
I was wondering if two Odyssey PC680s would be enough ?
I know that a couple of large optimas would work but unless I put them on my lap,
they wont fit !

Any experiences ?

 

I run an on board starter also , mezzerie with their 139 tooth billet flexplate. But instead of carrying two batts on board I use a small Braille 12 volt inboard to run electronics and use two large 12 volts wired to 24 volts on my golf cart to start with. If Nhra gives me any grief I just tell them I need a boost and hit the starter button, all it will do is click, which is the solenoid clicking. No problems yet and it starts every time quickly.

 

If you can, aviation batteries are 24 volt, and small! Concord is a gel cell like an optima. They are very expensive ($1500)....BUT, these batteries are KILLER. 600 amp hour. You go the whole weekend, maybe even month, without dealing with it. $150 battery minder/charger, and you are good to go. In addition, they have quick connects, that are very safe, and need no wrenches or have cable ends to deal with.

The Trick....Aviation batteries are only legal in the aircraft for 2 years (dated)...without a deep cycle service. This uses a $15,000 dollar machine, so most companies, "red" tag the battery, put them in quarantine and wait to throw them in the garbage. Find a shop (sherrif department !) or operation, and see if they have any old batteries you could have. Tell them what you are doing , and insist they deface, or scribe "scrap" on the battery, so they know you are legit, and not going to put it back into an aircraft.