I have used an EU3000is to power my 15k air conditioner, with lights and charger. My charger will pull 1000 watts for the first 15 minutes if the battery is very low. I know this can create a problem if the charge is at 1000 watts when the ac starts up so I sometime turn the converter off to give the ac a chance to get going.
I use the yellow adapter to convert from the twist lock to the RV receptacle. 1000 watts is quite a lot to run a charger. If yours pulls more than that, something is wrong, for sure.
