I have a dual charger that charges two batteries at 4 amps each, and I use the car receptacle all the time (in both cars). Nothing gets hot, never blown a fuse, etc. Works great! Not sure why Lipos would make a difference (I don't own any), but as long as you are charging at or below the rated capacity of the receptacle, I would think you should be fine.

If only I could run my xbox 360 from it...