Ammeter to Voltmeter...who does it?

toolmanmike said
You just answered your question as to why your alternator is constantly charging, The coach battery (or batteries) are shot. If your motorhome doesn't have a battery isolator you need to get one. I had chassis/coach batteries in 4 different tool trucks in 28 years of the tool business. @ trucks had isolators and 2 used a constant duty relay to charge the coach batteries. The isolator separates the 2 electrical systems and only charges the batteries that need the charge. Your engine start/chassis battery doesn't need much charge unless you are using the lights, heater, wipers, etc. If you use the camper for any length of time those batteries will need charged. With no isolator your system will charge one set and overcharge the other set. I had many battery and alternator failures because of overcharging in the trucks without a isolator. That bad coach battery will cause the system to overwork.

Yeah, I tend to think outloud, to make sure I'm on the right track. The Chassis Cab does indeed have an isolator....it's in one of the pics I posted. I tend to keep what the original engineers designed....I still run the original Prestolite ignition system on my CJ-5 and have had ZERO issues. If you talk to a good number of the AMC/Jeep guys, they'll refer to that system as Prestocrap.

In this case, though, my train of thought is that Mother Mopar could only anticipate so much, when they were building the MB chassis cabs....the motorhome manufacturers are the ones who throw the monkey wrench into the equation, when they installed their appliances/systems, and I want to make sure that my entire electrical system is up to the task of taking care of, not only the chassis cab components, but that it also has the ability to not falter, when it's charging the Coach/House batteries, while we're on the road. Since our fridge is 3-way, I prefer to run it on 12V, while we're driving, so that we don't run into any problems when we refuel. I've heard of fires starting, when RV'ers pull into service stations and their fridges are running on propane.