Not charging from alternator

Harvey51 wrote:
X2 on the previous post by PNichols.
You can just start the engine and check the voltage on engine and house battery with a multimeter. A loss of even several tenths of a volt diminishes the charging effectiveness. I found voltage losses in a connector, and a solder joint on our C. And changing the wiring so alternator current goes directly to the house battery rather than roundabout through the battery disconnect switch at the door. Fixing those made quite a difference.

Harvey, when you ran a new wire directly from the alternator to the battery did you remove the existing wiring, disconnect it at the alternator or just leave it in place for two charging paths?

X2 on the previous post by PNichols.
You can just start the engine and check the voltage on engine and house battery with a multimeter. A loss of even several tenths of a volt diminishes the charging effectiveness. I found voltage losses in a connector, and a solder joint on our C. And changing the wiring so alternator current goes directly to the house battery rather than roundabout through the battery disconnect switch at the door. Fixing those made quite a difference.

Kamphiker wrote:
Solenoid for the truck side to the House batteries failed 5 or 6 years ago.
I replaced with an upgraded Solenoid Trombetta "The Bear" contactor.



This was slightly larger (Dimensional) than the one Winnebago installed. It fit with room to spare.

Much higher quality than the Original I replaced.

I also replaced our Class C's stock charging solenoid some years ago with a Trombetta "The Bear" contactor. However so that I wouldn't get surprised ever again with low coach batteries after traveling when the alternator should have been recharging them ... I installed right on the cab dash two digital voltmeters to show both the voltage on the engine starting battery (IAW what the engine alternator is outputting) and the voltage on the coach batteries (IAW the charging voltage from the alternator whenever the engine is running.)

While going down the road these two voltmeters closely agree if the Trombetta solenoid has closed and is acting OK - or if it has closed but has so much corrosion built up on it's contacts that there is a voltage drop across it down from what the engine alternator is outputting, the two voltmeters will not read the same - the voltmeter for the coach batteries will read lower than the voltmeter for the engine alternator.

Any voltage drop across the contacts (due to their degradation from corrosion so as to have high resistance) of this solenoid will reduce the effectiveness of the engine alternator in it's recharging of the coach batteries.

Had to resolve this same issue on all 4 class C's over the last 20 or so years. Mr. Wizzard helped me out. The stock solenoid switches don't last. I used a NAPA continuous duty rated unit. Very common failure. In the unlikely event you have a solid state isolator instead of a solenoid, it is easy to test. The center post is common. By the way some of the failed solenoids I had to replace made a clicking sound, but the electrical switching did not work.

If a solenoid, it is probably failed, and if you replace it consider the Cole-Hersee 24213 as it is 200 amp continuous rated and has silver-tungsten plated contacts. Much better than the cheap ones the RV manufacturers install.

Charles

Solenoid for the truck side to the House batteries failed 5 or 6 years ago.
I replaced with an upgraded Solenoid Trombetta "The Bear" contactor.



This was slightly larger (Dimensional) than the one Winnebago installed. It fit with room to spare.

Much higher quality than the Original I replaced.

When I had the same problem I found that the problem was the continuous duty solenoid

This video may be of help to you. after I tested it out I found that it was not working so I changed it and now my alternator is charging the house batteries.

if you don't hear the solenoid clicking when you turn on the key look there first. not hard to change.

If your solenoid isn't making any sound when you turn the ignition key it maybe defective - they are easy to replace and don't cost much. Sometimes rapping it with a hammer will unstick it. SB some threads on how to test the solenoid.

Locate and test the BATTERY ISOLATOR.

If that is the problem, you can temporarily wire around it.

There are two types: diode-based and solenoid-based. Suspect you have a solenoid-based isolator.