Charging camper batteries while driving

[mtbdemon]

Hello,
I have a relatively new to me dodge 3500. I have two batteries for the truck and three house camper batteries. I am almost certain that when I first bought the truck it would charge the camper house batteries while the engine was running, but now it does not.
I'm getting good voltage from the alternator as the truck batteries show a shade over 14 volts when the truck is running. I do have what I think is a solenoid that keeps my camper from discharging the truck batteries. Could this be the source of not charging the house batteries? All fusses seem to be okay but I do have a couple relays that the wiring could go threw but I have no way of testing those.
With all of that, what say the forum? Thanks

Ken

[BFlinn181]

Have you checked that 12 v is flowing through the cable connecting TV and trailer? I'd check there first.

[mtbdemon]

Sorry, I should have been more specific. I have an in the bed, slide in camper. If I tested the correct line, I don't seem to have power going to the plug in that charges the camper batteries. I hope that is clearer. Thanks for the input....

[Scotty14]

Check the battery disconnect switch in the camper. Should be on.
Scott

[Libero]

Originally Posted by mtbdemon

Sorry, I should have been more specific. I have an in the bed, slide in camper. If I tested the correct line, I don't seem to have power going to the plug in that charges the camper batteries. I hope that is clearer. Thanks for the input....

You noted you checked the fuses but I expect there is a fuse, and possibly a relay and perhaps a diode in the circuit.

You need to trace the plug wires back in the truck to see where the voltage is present, hence where the open connection is.

I suspect you do not have a line signal tracer, but if you can get one, these are excellent for sniffing out wire routing, you would put the signal on the plug wire that goes to your camper battery and with the sensor probe, trace the signal until you cannot detect it and where the signal is lost, you will have found the specific area where the circuit is open. I have one and it is a valuable device for a variety of wire tracing applications in the house, Car, RV, aircraft etc.

It could just be a bad connector also. You might want to look at every place there is a connection/splice etc.

Some people stick pins in wires to detect where voltage is lost, but that method can be a source of future corrosion by exposing the wire to the elements if the pin holes are not sealed after the pin is retracted.

Good luck.

[jesilvas]

If you have no 12V coming out of the truck socket, then you need to check fuses and relays if any. Just find the last point of power, and then whatever is in between is that bad component.

[mtbdemon]

Fantastic info!! Any suggestion on the type of signal chaser to purchase? Amazon? Thanks

[targaboat]

About a $10 volt/ohm meter. I never leave home without.

[Libero]

Mine is a TT100 Tone Tracker made by "Test-um Inc." Thier web site is "testum.com" But if you search on google or amazon for a signal tracker I suspect you will get many hits. There are several manufacturers. I don't recall what mine cost, not a lot, I have had it for several years after my very old one I got in the 60's died.

ps: just looked at that web site. Test-um was acquired by JDS Uniphase in 2006 but still in business.

[mtbdemon]

I'm not sure how to test it, but could the culprit be the relay (?) that keeps the camper from discharging the truck batteries when boondocking?

[Luv2go]

Yes the solenoid could be it. I use a DMM to test them, they can be had at Harbor Freight for $5 or so. I would look on both sides of that solenoid while the truck is running, if you have 14V on one side and the house battery voltage (whatever you read across the house batteries, probably 12 to 12.5V depending on how charged they are) on the other the solenoid could be bad. Otherwise trace the wire back towards the camper until you find where the voltage drops to the house battery voltage and you should find the open wire or connection.

If you find the solenoid looks bad make sure you have coil voltage, that will be 14VDC (from the engine) either across two small wires going to the solenoid or from a small wire to ground going to the solenoid. Coil voltage will somehow be provided by wiring from the battery through the fuse block and ignition switch, or possibly the alternator field winding if the truck is old enough.

If you do find the solenoid is bad make sure you buy a continuous duty one. Keep in mind the PO may have replaced the solenoid with a starter solenoid which is only good for short uses (10-20 sec), so you may have to research the part number to make sure it is continuous duty.

[Libero]

Originally Posted by Luv2go

Yes the solenoid could be it. I use a DMM to test them, they can be had at Harbor Freight for $5 or so. I would look on both sides of that solenoid while the truck is running, if you have 14V on one side and the house battery voltage (whatever you read across the house batteries, probably 12 to 12.5V depending on how charged they are) on the other the solenoid could be bad. Otherwise trace the wire back towards the camper until you find where the voltage drops to the house battery voltage and you should find the open wire or connection.

If you find the solenoid looks bad make sure you have coil voltage, that will be 14VDC (from the engine) either across two small wires going to the solenoid or from a small wire to ground going to the solenoid. Coil voltage will somehow be provided by wiring from the battery through the fuse block and ignition switch, or possibly the alternator field winding if the truck is old enough.

If you do find the solenoid is bad make sure you buy a continuous duty one. Keep in mind the PO may have replaced the solenoid with a starter solenoid which is only good for short uses (10-20 sec), so you may have to research the part number to make sure it is continuous duty.

Hmmm - why or how would a solenoid be used for this application. I would think if there is any secondary switching it would be done by a relay. Just curious. I am not familiar with that vehicle and how it would apply voltage to the camper, but selenoids are used when one needs to take an electrical current and make some mechanical actuation other than closing/opening another electrical circuit. As in the Starter Selenoid referred to. And indeed the relay would be continious duty, if there is one in the circuit.

Always looking to learn something.

[wrvond]

Originally Posted by Libero

Hmmm - why or how would a solenoid be used for this application. I would think if there is any secondary switching it would be done by a relay. Just curious. I am not familiar with that vehicle and how it would apply voltage to the camper, but selenoids are used when one needs to take an electrical current and make some mechanical actuation other than closing/opening another electrical circuit. As in the Starter Selenoid referred to. And indeed the relay would be continious duty, if there is one in the circuit.

Always looking to learn something.

I would suspect the label solenoid is being used interchangeably with relay here. While technically incorrect, he's still getting his point across, it would seem.

[Libero]

Originally Posted by wrvond

I would suspect the label solenoid is being used interchangeably with relay here. While technically incorrect, he's still getting his point across, it would seem.

I might have thought so except for the reference to the starter solenoid. That is truly an application where the actuator physically moves the starter components versus a relay which only makes or breaks an electrical connection on a secondary circuit. I don't even know why there would be a relay for that application, but I am always in the learning mode. Perhaps only to apply voltage when the engine is running?? Could be. Sounds reasonable.