How to Use to Motorhome Alternator to Charge Main Batter and/or Auxiliary Battery

Updated 02/01/2022 | Published 01/31/2022

Products Featured in This Question

Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp

(12)

$165.00

100-Amp MIDI Fuse Kit for Redarc Smart Start Battery Isolator

$230.00

Question:

I have a 250 amp high output alternator, a 200 amp hour main vehicle battery and a 450 amp hour rv batterys, would I fuse my vehicle batterys 200 amp fuse, the rv batterys 450 fuse, and the alternator 250 amp fuse, or would I fuse the batterys the max output amperage of the alternator divided in half? and if I havent gotten my alternator to work with my isolator already should I switch to an isolator with an excitor post? I currently have a three post isolator that I havent gotten to work

asked by: Jonathan F

Expert Reply:

From the sound of your question, it sounds like you are trying to use your motorhome's alternator to charge your main battery along with an auxiliary battery. It also sounds like you already have a battery isolator, and that is exactly what you need. If you do not have one (or if you discover that yours is defective), a great alternative is the Redarc Smart Start Battery Isolator - 12 Volt - 100 Amp # 331-SBI12 along with the fuse kit # 331-FK100. I went ahead and attached a diagram of what this setup will look like.

If you still have questions or concerns, feel free to respond to this answer.

expert reply by: Bob C