Community Forums

fry5family · 03-17-2022, 09:40 AM

We are full-time RVers. We have a 2005 Monaco Knight with a Cummins 330ISC.

During the last 20 miles to our boondocking spot yesterday, the Alt Chg indicator light and warning would cycle on for a while then off.

The meter on the dash normally shows 13.5v, but it would slowly increase to about 13.75v and the warning would start. The meter would gradually drop to 13.5v and the warning would stop. This repeated 4 times.

The 2 NAPA commercial AGM 12v chassis batteries (2 years old) are sitting at 12.86v.

What would make the alternator charging go up?

Daytime running, just the blower fan, Garmin, and radio. Cycled again after turning those items off.

Mike Fry
2005 Monaco Knight

John Hilley · 03-17-2022, 11:18 AM

Sometimes mine does that also. It is the Solar Charging causing it. Either turn off the solar or disable the solenoid that ties the House and Chassis Battery Banks together when ignition is on. Doesn't seem to have an any detrimental effects.

MechEngrSGH · 09-09-2022, 11:08 PM

A coach of that age will have a fixed voltage output alternator that should be regulated between 14 and 14.2. That should maintain a system voltage of 13.8-14. 13.5 is really too low. 1) You could be seeing the EOL of your alternator. 2) You could have some loose or corroded cabling in your charging system. Since your batteries are at full charge, it is still doing the job but I would consider taking it off and to an auto parts store that can test it.

computerguy · 09-10-2022, 04:41 AM

I had a 05 Knight I did solar on way back when. Same problem. The voltage of the solar was letting it get too high so the system thought. I simply drove with the headlights on and the problem went away.
As others said you could disconnect the chassis from the house batteries.
I saw no adverse affects thought so simple drove with the lights on.

twinboat · 09-10-2022, 05:55 AM

Alternator regulators are dumb.

They only know that if voltage going to them is higher then they are set to, the light comes on.

Any generator or solar charging to the house batteries can cause charging to the chassis battery, in many systems, thru the isolation, BIRD system. That charging tricks the alternator regulator into sensing no charge and the light comes on.