Yes you can use a portable charger to recharge all the batteries, but you might find they are too far gone to be usable again depending on how long they have been "dead." Have to try it and see.
Meanwhile, your 30/15 adapter should be fine to run just the converter so it can recharge the house batts. Perhaps you have too many other 120v things "on" for a 15a? Especially the water heater, or any kind of electric heater.
What "rims become charged?" You mean you get a tingle from touching the wheels? That's a different issue to do with grounds etc. Must be fixed!