I have replaced my 2 12 volt batteries with 2 6 volt batteries a while ago and noticed that while my truck is running my charge idicater on my panel in the trailer does not show full 4 bars of charging. it only shows 3 out of 4 bars. with the gen running it goes up to the 4th bar. i have disconnected the batteries while plugged into the truck and have power to everything so i know its getting power. is this normal or do i have to spend more for a more advanced inverter? ken