Hello Bill,
I use LiFePO4 batteries from Tracer: https://tracerpower.com/products/product-category/batteries/
It all depends on how much power and for how long you want to use. I have 8 and 16Ah Tracers.
I also have a Tracer Li-polymer battery but it is not really up for my AZEQ-6. Hence why I switched to LiFePO4.
Jeremy
