A car battery with 300 cranking amps could provide 3600 watts. So 2 car batteries should do it, maybe not continuously for a long time though and you'd probably need pretty beefy cables if you have them in parallel.

Whether you want them in series or parallel would depend on what you're diving with it. If it needs to be converted 120/240v ac you'd have to go through an inverter so in that case series would be better. If that's the case I'd suggest 4 car batteries in series so you have 48v and require substantially less bulky cables. There are inverters used for solar setups you can find online that should be able to handle it.

A car battery with 300 cranking amps could provide 3600 watts. So 2 car batteries should do it, maybe not continuously for a long time though and you'd probably need pretty beefy cables if you have them in parallel.

Whether you want them in series or parallel would depend on what you're diving with it. If it needs to be covered 120/240v ac you'd have to go through an inverter so in that case series would be better. If that's the case I'd suggest 4 car batteries in series so you have 48v and require substantially less bulky cables.