Battery not Charging

[karenor59]

I have a Bigfoot truck camper and it seems that the battery is not charging when the truck is running. I have a relay installed in my 2000 Ford F350 for charging. I checked the constant terminals at the truck plug and it tested at 14.2V output but the monitor does not show that the batteries are charging when the camper is plugged in to the truck. When I have the power cord connected to a 120V power source, the monitor shows that it is charging and I get 13.2V at the battery connect terminals in the fuse panel. When I disconnect the power cord and have the truck running, the monitor does not show that it is charging and I get 12.5V at the fuse box terminal, the same as what I get at the batteries when there is no charging going on.

Does anyone know how to diagnose the problem?

[DrewE]

It sounds to me like there may be a bad or broken connection in the trailer wiring between the truck plug and the trailer battery, as you've apparently verified things on the truck side pretty well. It should be a theoretically simple job to track it and see where the charge voltage disappears (though it may be practically rather more difficult due to tricky wire routing). There likely is a fuse or circuit breaker in the trailer somewhere near the battery for this connection, and possibly it is blown--or possibly the charge wire is not actually connected to the battery.

It would also be good to verify that the trailer ground connections from the hitch connector, and the corresponding ground connection on the truck, are good and solid, though a bad (enough) ground would also affect the trailer lights and brakes.

[1492]

Moved from Forum Technical Support

[karenor59]

I checked the fuse and it's fine.

[pianotuna]

Check the fuse under the hood that is intended for trailer charging. Mine blew several times. It is a 60 amp fuse.