Community Forums

oh no · 10-12-2016, 06:32 PM

The motorhome is not charging the coach batteries running down the road. It works fine plugged in or the generator running. I noticed on last trip energy management screen showing 9 volts lights were weak. I started the generator starting charging the coach batteries. It is in the shop now, I talked to the tech today and they have talked to Monaco. Still at a loss on what is going on. Any suggestions on this to point us in the right area? They are looking at the circuit board in the front electrical box. The starter batteries are charging fine.

deSanford · 10-12-2016, 10:01 PM

Just a wild guess check the batteries solenoids. I believe one of them is activated when the chassis battery is fully charged, and then the coach batteries get charged. Monaco service center should know which relay could be bad, and it is I believe on the circuit board. The techs should be able to direct your shop to the right part.

l1v3fr33ord1 · 10-13-2016, 04:51 AM

oh no-

It's hard to know for sure, but typical Monaco coaches of your vintage have a circuit board, called an "Isolator Relay Delay," mounted to the Front Distribution Panel. The IRD allows/disallows chassis alternator charging current to flow to the house batteries. The other components involved in making the charge circuit work are a relay and the battery boost solenoid. But, I'd suspect the IRD first.

My coach has a BIRD (Bidirectional IRD, allowing charging in both directions), and when I purchased the coach last December the BIRD had failed. I replaced it.

If you don't know where to find the IRD (if your coach has one), then open the Front Distribution Panel and look for a roughly 2" x 3" x 1" block. It may be marked "Intellitec." The IRD will be below the long row of fuses, left of the panel center.

If you confirm your coach has an IRD, we can suggest test steps to confirm if it's working (or not).

xydial · 10-13-2016, 07:43 AM

Probably is the Trombretta solenoid located above the batteries. This is also used as the "battery boost" solenoid.

The contacts tend to corrode over time. You can test the solenoid by pinning the battery boost switch up and checking the two large connections to see if they read the same voltage. You may need to try several times since the problem usually is intermittent.

If you decide to replace, get a replacement with silver contacts. Will last significantly longer. I ordered my replacement from Amazon.

bborc · 10-13-2016, 02:39 PM

Xydial has it right. I have a 07 Knight and the same thing happened. Replaced large solenoid above batteries and has worked fine.

Neverhome2 · 10-14-2016, 02:07 PM

Could be the alternator too. The Duvac wire must be hooked up to charge the house batteries. When we bought our coach the alternator had been replaced sometime in the distant past and it didn't have the Duvac post. Replaced with a Delco 28SI which has the Duvac post and it works great.