Battery won’t charge on shore power

Carolyn

we just replaced the battery in our CS and I noticed that it did not charge at all during a recent weeklong camping trip at a state park with 30 amp service. When driving home it charged fine. The floor was recently replaced in the camper. Could something have not been hooked up properly? What suggestions do you have to check? Thanks

jkjenn

Here are a few things to check if you have not, already:

1. Do a visual inspection of the converter. Does everthyibg look like it ought to look?
2. Check your 30 amp battery fuse.
3.  Look at the black 12v junction box outside of the camper. It is possible something got knocked, there.
4. Check the water levels in your battery.
5. Check your battery. If you have a DM you should have positive and negative wires going to and from the battery.

Lastly, it could just be bad luck for you and you need a new converter.

Sharon_is_SAM

@Carolyn, the inability to charge when on shore power suggests an issue with the converter.  I assume you do not have a battery cut off switch which if turned off will prevent charging as well.  

Was this the first time connected to shore power since the flooring was replaced?  It may well be simply a loose connection or a wire got switched.  Show us some converter wire pictures.  Also, change out the 30 amp battery charger fuse in your panel and see if that helps.

ScottG

Since the battery charged fine while you were driving, that suggests the battery itself is fine and is still connected to the tow vehicle via the front junction box.

You didn't indicate any issue with your 12V devices (lights, fan, water pump, etc.) while on shore power. That suggests the converter itself is okay, but it's connection to the battery may be broken.

In order, here's what I'd check:

1. Do 12V devices work on battery power only? If so, it's not a connection issue and I'd suspect the converter's internal battery charger is faulty. If not, continue...
   
2. Two battery charge fuses in the converter panel (one for the charge line--probably 30A--and one to protect against reverse polarity--probably 40A).
3. The wiring harness behind the converter (1st photo below). The little bullet connectors are not particularly robust and can wiggle loose. The red wire should be the one running to the battery.
4. The connection between the converter and the junction box (2nd photo below). If the converter is not connected here, it will remain isolated from both the battery and the tow vehicle.

Keep in mind that different T@Bs may be configured a little differently, so yours may not be exactly like mine, but the same principles apply. Good luck and please report back what you find.

Sharon_is_SAM

@Scott - I always learn something from you!  Very logical steps!

Carolyn

Scott, thanks for the comprehensive answer. I have a new battery and recently changed the fuse. I, too, suspect the converter. I assume I will need to remove it to see the wiring. Thanks

Carolyn

After testing the red wire in the box under the front of the camper, we decided that there was power to that point. When he battery is off and plugged into 30A there was np power inside the camper. I pulled the 40a fuse at the bottom and it looked fine. When I placed it back in the fan came on for a short time. The same thing happened with the 30a.  Do you think the converter is bad? I have not tried to look behind at connections yet.
thanks
carolyn

ScottG

@Carolyn, can you clarify which red wire you tested? Was it the one that runs to the battery or the one that runs to the converter?

Also, when the battery is on but the trailer is not plugged into shore power, do your lights, fan and other 12V devices inside the camper work properly?

Lastly, when plugged into shore power, do your 120V only devices (such as your air conditioner and electrical outlets) work properly?

It sounds like it could be pointing to the converter, but I can't say that confidently without more specific information. There are lots of places in the circuit where things can get disconnected and cause the symptoms you describe.

dragonsdofly

@Carolyn, time for the "electritians smoke test" I fear. Wet your fingers, touch each wire you are referring to one at a time. When the smoke comes out your ears, you have the "hot" (powered) one. Just kidding. Good luck with this!