We are repowering from a gas to a diesel motor. I was thinking about adding a dedicted 3 battery just for the motor. I don't want of need it tied to the current house batteries. He is my idea add the 3 battery soley for starting, hooks all batteries up to the alternator for charging, and also to the charger, we have a Xantrex Truecharge 20 that will charge 3 batteries. would this setup be fine? Thanks.