Inverter Generator... what would you buy?

I sure like the Champion 2000 (reconditioned) prices...

I thought it was better to charge a deep-cycle battery slow, not fast?

Using a low amp charger means running the gen extra long times, so you need lots of gasoline for it. So now another consideration is whether it has a fitting for an extra gas tank, or if you are using Jerry cans for that.

A single 100AH battery can take 30amps initial charging, so a 25amper would be way better than a 6amper.

Note that the 8amp DC output is 'dirty DC' not well regulated. When running that you don't use the 120v side at the same time. Unlike with a proper battery charger, where there might be some extra VA in the gen to run some other things in the rig at the same time besides the battery charger--especially as the amps taper.

What's your budget? A Champion 2000 can be had for less than $500 and works well for lots of folks (including me). For about twice as much you can get a 2000W Honda or Yamaha. Any of them will probably do the job. If you really want to cheap out, get the $75 one from Harbor Freight but it's two stroke, noisy, and stinky.

If you have sun I would get 120 watt to 240w solar panel and controller.

Otherwise Honda/Yamaha 1000w would be my choice. I would also get a 15a to 25a automatic portable charger if you do not have a multistage converter that functions properly.

OK, I'll use a Diehard 6-amp charger... there is no 120-volt power in several miles of this location. Many inverter gens do have an 8-amp charging circuit.

Honda 2000

Gens don't charge batteries, they run chargers that do that. The gen must have enough VA output to run the charger at the charger's rated DC amps output. This is true regardless of the number of batteries being charged at a time.

So the OP needs to say what charger he is going to be using before we can say what size gen it needs to run it.