[Allan_L (Allan)]

Hi John.
From my experience, most people use a 12v deep cycle battery.
The size you decide upon will depend on what else you power from that same battery, and how long you want to run.

Generally, 17 Ah (Amp/hours) is a minimum, and these are often found in inexpensive Jump starter packs. (see image for example). But even these will be around $100.

If you have several dew heaters powered off it as well, you may need more.

I run a 36 Ah deep cycle battery from Waeco (image2) but it cost me $330.

Have a look at camping places like Rays Outdoors for other options.