Community Forums

JusBcuz · 06-23-2017, 02:13 PM

Does anybody know where the battery disconnect is on a 1978 Sportscoach? it has 2 house batteries in the very back hatch but I cannot locate the disconnect also cant seem to use 12v house electric without the ignition being in the ACC or On position, is that normal? Not sure if it makes a difference but it is a Dodge Chassis...
Thanks, John

BFlinn181 · 06-23-2017, 07:53 PM

If you have a battery isolation relay, turning it on/off should make an audible click you can follow to the relay. It's not normal for the house system to come on with the ignition ACC position. With a test light or multimeter you'll have to trace the power from the batteries to your converter/charger and fuse block.

ahicks · 06-25-2017, 07:33 AM

Regarding no 12v. unless the key is on, at that point you are likely supplying power to the coach from the main/starting battery. It's supplying power through a relay that would normally be supplying 12v power used for charging the aux. batteries.

From the sounds of it, there's some kind of issue between the coach 12v system and the aux batteries. A test light or voltmeter, used to follow the power from the aux batteries, should lead you to your problem. Could be the aux batteries are dead, a broken wire, a bad fuse, corroded battery connections, etc. That's why I would start at the batteries. Make sure you have power there, and then just follow it forward - likely to wherever the power converter is located.

JohnBoyToo · 06-25-2017, 08:16 AM

I guess we need to ask Why are you asking?
Maybe it's just me, but I see a couple of ways to read your issue

If you are asking because you WANT to disconnect the batteries, then just pull the neg battery cable as a temporary measure until you can locate the switch (if there is one!)

JusBcuz · 06-26-2017, 08:09 AM

I'm asking because I cannot get electric in the motorhome without Gen or shore power are hooked up the house batteries don't seem to be connected, that's why I was asking about the disconnect switch thought maybe it was disconnected but I cant find the switch...Thanks!

BFlinn181 · 06-26-2017, 09:14 AM

Starting at the house batteries, you should have a large circuit breaker (or fuse) in the (+) cable. The (-) cable should run to a ground. I'd remove the ground cable and clean the connection point. If you trace power through the CB on the (+), it should lead to the house fuse panel. That should be connected to the inverter/charger.

Still thinking of getting house 12v when ignition ACC is on, I'd look to any previous owner added items that might be wired to both chassis and house systems. This should not be normal and could cause issues if too much power tried to flow through that path.

twinboat · 06-26-2017, 09:31 AM

The power with the key ON may be normal in that era motorhome.

My 1999 Class C, E450 uses the key to actavate the charging solenoid. No fancy, electronic voltage sensing relays.

As mentioned above, follow the house battery voltage ( if the batteries are charged ) from the + terminal towards the fuse panel. There is a fuse, breaker and maybe a switch on that circuit.