Does anyone know how big the 12v plugs are for the ecotech? I have two but .. if anyone knows I will ebay them.

I have 20 AGM batteries from our work UPS that are retired but still good, one of these has 5 times more amp hours than the default ecotech and I could set up my apex battery backup too. Heck I could set it up to run for a week with no power (except those damn heaters ....)