Inverter shutdown when chassis starting

[cfoye]

I recently installed an inverter connected to the house batteries, whenever I start the coach the inverter faults out, low voltage. I then need to cycle the power to clear the fault.

Question, why would the coach batteries be drawing power from the house batteries when starting?

Chris

[cfoye]

I recently installed an inverter connected to the house batteries, whenever I start the coach the inverter faults out, low voltage. I then need to cycle the power to clear the fault.

Question, why would the coach batteries be drawing power from the house batteries when starting?

Chris

[Gary RVRoamer]

Good question. There is probably a relay that allows cross-connecting house and chassis batteries for emergency starting - maybe that relay is stuck in the closed position (it is normally open) or the switch for it has shorted and causing the relay to stay closed.

In newer rigs the house charging system may also charge the chassis battery, to keep it topped up while in shore power for extended periods. There is supposed to be isolation to prevent drawing power in the other direction, but maybe it has gone bad or was miswired?

There may also be an accessory installed that is effectively cross-connecting the two battery systems, i.e. it is wired to both the hose and chassis batteries. I've seen that done to make an accessory work "both ways", but it will cause problems like yours.

What's the condition of the house batteries?

Is your inverter an integrated inverter/charger like a Heart or Xantrex, or is it an add-on inverter only, with a separate converter/charger for charging. Each has different wiring and differing possibilities for this sort of problem.

[cfoye]

I have an add on inverter fully fused from the house batteries. But, I'll have to check for a stuck relay or cross connection.

Thanks,

Chris

[Gary RVRoamer]

Yeap - something is letting the engine circuit draw power via the house batteries. Or possibly generating a power spike back to the house system - really nasty voltage spikes are generated when the starter motor turns.

By any chance is there an auxiliary charger for the chassis battery plugged to an inverter-powered circuit? That creates a power loop of sorts because the inverter draws house power to try to re-charge the chassis battery during starting. An auxiliary charger should not be plugged into an inverter-powered outlet.