I recently discovered that the slides and front landing gear on our Bighorn 3610 RE will not operate unless plugged into shore power. While checking the battery I discovered that it was drained and very low on fluid. I had a backup car battery so installed it but the slides and landing gear still do not work on DC power, only when plugged into shore power. Is this because the car battery is not sufficient enough for their operation, or is there a problem with the converter?