What is the minimum gas generator wattage needed to charge the EP500? What about the EP500Pro?
Hi @Mlummus , EP500PRO AC Input 3000W Max
EP500 AC Input 600W Max
This is the maximum AC input for both of our models. As for the minimum value, it may be more intuitive to refer to your gas generator parameters. 
Hi @Mlummus welcome. I can speak to the EP500 Pro, in the default options enabled it charges up to 15A (1800w) but there are options to increase (30A) or decrease (10A) that (provided you ask Bluetti for the unlock code). This is directly using the various AC connectors.
Another option is to slowly charge using a T500 AC adapter (500w), this hooks up the DC input. Technically you can use 2 on a single EP500 Pro. You can also use these adapters in conjunction with the AC input.
With all this said about using a gas generator, once you purchase one of these power stations the allure of using some solar panels becomes almost a no-brainer. At least it was the case for me. I look back and wonder why I even worried about the gas generator. Good Luck!