checked their site, they literally have all the info on there, product seems supercool!
they use regular 6s lipo and seems to be integrated into a 12s2p meaning 4,2*12 = 50.4V fully charged 4 car batteries fully charged = is 12.7*4 = 50,8V, hence why they say you can use 4 regular car batteries.
they say you can get 20-30 pulls out of 8000mah , and you get to use say 80% out of the 8000mah or 8ah, used 6.4ah ish and lets use nominal voltage 3.7 for the math which means about 280 ish watthours.
car batteries will be wayyyyyyyyyyy heavy and have less power. When we done similar projects to save $$ we would just have a car running and charge the lipos from that, you will be enable to run it nonstop by having a car chargeing the other set, or using a 110V source.
Depending on how much it pulls, and if you have issues, you can use a $10 LIPO warmer bag with a $10 lipo to keep it warm and give you full power.
https://cdn.shopify.com/s/files/1/0112/4558/4446/products/Rewinch_Render_049_896x896.png?v=1564586962
**This post was edited on Nov 28th 2020 at 3:15:01pm