House batteries not charging, remind me this is fun !

[NoImMad]

Melbourne 2009Ford 450
I have this motor home just over a month. Revived it with mis-matched batteries and thought replacing them was prudent. Two new flooded Interstate 12V I put in today. Checked and it is evident that the Ford motor is NOT charging the batteries. The on board generator does. Now THIS is very awkwardly placed behind the batteries
ALL of those terminals appear to be getting 12.4V from the house batteries. Turning on engine makes no difference. There is one battery type cable that was taped off and not connected but it appears useless as there is no voltage in any scenario.
IS that really the part I’m looking for? Voltage does not change when generator is ON and batteries are getting 13.5V.
I have seen the instructions on how to test it and tried every conceivable combination and I can not find 13V on any of those cables. I grazed my knuckles up putting numbers on it to avoid confusion when you folks explain to me what I’m doing wrong. Thanks and apart from this, the BLM in Quartzite is fantastic.

[dvspl]

The pictures that you posted appear to be of the main battery disconnect relay. That relay controls 12V power to the coach but doesn't have anything to do with charging the house batteries from the alternator. Charging is enabled by a different relay that connects the chassis battery to the house battery. On my 2019 E450, it's under the hood on the driver's side. Look for it and make sure it's engaging. The solenoid is supposed to close when the engine is running so test it to see if you get 13+ volts between each side of the relay and ground when the engine is running.

[NoImMad]

This IS under the hood driver side and has a mounting screw that most certainly does not appear to be factory installed.
Just knowing I’m barking up the wrong tree assuming that the relay right Next to the battery was it.
So the one under the hood as pictured is likely the culprit.
UNLESS of course the coach is smart enough to charge from the engine ONLY when the house batteries are severely depleted which any conscientious boon docket avoids at all costs !

[JimD]

To me the picture does indeed look like the relay/solenoid that connects the engine charging system to the house battery since you mentioned it is under the hood. It is very easy to troubleshoot. I have attached some troubleshooting info that should help. I had to replace mine.

[pconroy]

Originally Posted by NoImMad

Melbourne 2009Ford 450
Checked and it is evident that the Ford motor is NOT charging the batteries. The on board generator does.

Here's a picture of the battery isolation solenoid under the hood on mine. You can see when engine running the bottom terminal is at 14+V. That means the alternator is sending the juice back to the house batteries.


I'm told these solenoids can fail.

[NoImMad]

Thank you.
Sorted it out eventually. It is the one under the hood and it is definitely deceased. Using logic and figuring that the solenoid is just a switch, I jumped the terminals and surprise, STILL NO VOLTAGE at the battery. Then I remembered the suspicious taped off cable in the battery box and VOILA, 13.9V in that cable. So for whatever reason, someone knew there was an issue and disconnected the cable.
Anyway, end of the day you many good people here have saved another poor soul many dollars and who knows what grief getting it looked at by a shop, IF you can find one not booked up for the next decade. I just hope that I will be able to help in the future.
Thank you all.