Charging house batts while driving

Here is a pic of the diagram with a battery isolator.

Yes, it looks like an old Ford starter relay.
Some, like mine, require the chassis battery to be up to a given level before the charge relay energizes.
The charge relay is the same one used for emergency start function.

The relay that ties the 2 sets of batteries together, is only supposed to be used for starting. If the coach battery voltage goes low enough, that it won't start the engine, assuming the house batteries are in good shape, there is a button on the dash that will temporarily tie the two together, to help it start.

It is a momentary switch, and as soon as you let go of the button, the relay drops out and the 2 are separated again.

There is however, a black box near the batteries, (or should be) that the charging wire from the alternator goes into, and then it is split, so that both sets of batteries get charged at the same time, but will not backfeed into each other.

There is nothing to do, it is automatic.

does relay look like a old ford starter soliniod

when ign. is on should get 12 volts to small wire if not maybe a fuse or wiring problems

allbrandauto wrote:
it works by sending 12 volt ign. feed current to small wire on soliniod connecting the 2 bigger wires together allowing the alt to charge the batterys

Sorry, I wasn't very clear. What exactly triggers the relay? This one never gets energized (no 12V at trigger wire) although I can jumper it and it works. Is it supposed to happen automatically when the eng is started or when ever the ign. is on?
The house batts are not being charged while driving.

it works by sending 12 volt ign. feed current to small wire on soliniod connecting the 2 bigger wires together allowing the alt to charge the batterys