12 volt system question

[RockwoodMini]

Recently purchased a 2018 Mini Lite. The 12 volt system was working fine. Took it to have some service done to it and get winterized. Just brought it back home yesterday evening. Today the 12 volt system is not working. Checked fuses that I knew about, even put a new fully charged battery in. Still doesn't work.
However, for some reason when I plug the 7 way power cord into my truck, all of the 12 volt items work. I am stumped as to what allows the truck battery to work but not the battery on the camper.
Any ideas?
Thanks,
Ed

 

[TacomaJoe]

If your truck can power things the issue is between the battery and 12V buss. I'd look for a switch in the battery line. Have you found/checked the circuit breaker on the frame.

Also on the list is to ensure that the battery negative to frame connection is good.

 

[TitanMike]

A friend I installed a new batterybsystem asked the same question after taking her RV in for some service.

Turns out the shop turned the batteries off at the battery disconnect switch. She never used this switch so she never thought to check.

Some shops may do this to make sure batteries don't go dead while sitting. When winterizing for a customer it's logical they could think they'll sit til spring.

On a trailer the 12v wire in the 7-wire cable is connected to the "house side " of the disconnect switch.

Look under the propane tank for the disconnect switch and make sure it's on.

 

[RockwoodMini]

I was not able to locate a switch in the battery line, nor the circuit breaker on the frame. I will look again tomorrow. I did check the battery negative to the frame and it appears clean and secure.
I believe something happened during the service visit because when I picked the camper up, it was dark inside the camper. As soon as I plugged in the 7 way, the interior lights came on and the fridge indicator light came on. So they left switches in the on position and the lights would have been illuminated while waiting for me to pick it up (the service center was closed for the day when I got there).

 

[RockwoodMini]

I thought it could be the disconnect switch too. I tried it in the on, off, and the key removed positions. Same results for all. Can those switches go bad?

 

[TitanMike]

I thought it could be the disconnect switch too. I tried it in the on, off, and the key removed positions. Same results for all. Can those switches go bad?

Yes they can.

Batteries could be dead I'd shop left a lot of 12v items on. Wouldn't be the first time that happens at an RV service facility. If you checked batteries after plugging in 7-pin connector and towed trailer any distance chances are they got some charge, especially if you turned off all the items they left on.

 

[handyman58]

I have a 2020 mini lite 2109s and the battery shut off is located under the front near the propane tanks\battery box. You almost have to get down on your knees and look up to see it. Good luck.

 

[Aussieguy]

if you find a shut off switch and it appears to be bad

you can bypass it by putting all the wires on ONE terminal of the switch


IF there is a bunch of wires on the switch ...........take photo of original wiring so you won't forget which wire goes where.

remove battery negative cable before working on the switch.

since you got it winterized they may have disconnected / switched off the battery so you don't try to pump water from a empty tank...

 

[aceinspp]

I would still check the battery make sure its fully charged. Then look for switch. There is a inline fuse located in this circuit. Later RJD

 

[Aussieguy]

The disconnect switch "usually" isolates the battery from the converter
thus it won't get charged .... lead acid battery needs to be kept on some sort of charger even while in storage


solar "usually" is connected so the disconnect does NOT go through the battery disconnect switch... it can still charge your battery even if the rest of the 12v stuff is disconnected



look for these near battery

Breaker https://www.google.com/search?q=12v...iAYBkAYIkgcEMS4xMqAHsc4B&sclient=gws-wiz-serp

disconnect switch https://www.google.com/search?q=bat...0363350452753219,pvt:hg,pvo:3&oshop=apv&pvs=0

 

[jjscsix]

Buy a cheap volt meter and just start checking voltage starting at the battery then after every switch or fuse. Should be 12 volts +/- a half volt or so if it is not in some sort of charging mode, and 13.2 or so if it is receiving a charge.

 

[5picker]

When diagnosing electrical issues, one must first start with the basics. You mentioned you found the cut-off switch and the 12v circuit breakers and you mentioned when connected to your tow vehicle, you found lights and other things that were left on by the dealer.

With that said, I never read where you checked/tested the battery voltage with the tow vehicle disconnected. We need to know what you battery status is before we can recommend a course of things to check.

One just chases their tail by looking at wiring, replacing switches and circuit breakers if you have no battery voltage to begin with. It seems your dealer did you wrong by leaving things turned on without disconnecting the 12v system and possibly damaged your battery by discharging it completely.

 

[Chuck_S]

Good luck.

even put a new fully charged battery in.

My knee jerk reaction whenever I read this is the battery was installed backwards. This blows the pair of 40a battery protection fuses in the center of the power center and prevents charging or using the battery. Even if the battery is later installed correctly nothing will work off the battery until these fuses are replaced.

White wire is ground to the trailer frame. Wire from the negative battery pole goes there. DC wiring code colors are different from what many expect.

-- Chuck

 

[TacomaJoe]

Good luck.

My knee jerk reaction whenever I read this is the battery was installed backwards. This blows the pair of 40a battery protection fuses in the center of the power center and prevents charging or using the battery. Even if the battery is later installed correctly nothing will work off the battery until these fuses are replaced.

White wire is ground to the trailer frame. Wire from the negative battery pole goes there. DC wiring code colors are different from what many expect.

-- Chuck

On mine, the reverse polarity diodes break the connection to the battery which will also prevent the truck power getting to the lights/fans.

 

[bweigele]

My trailer has 3 breakers like the one in the above picture. On the side of one of them is a very small reset button. Push the button then check and see if you have power. I had the same problem on my Flagstaff last week and the reset button fixed it. The button is very small.

 

[RockwoodMini]

Following up...

I put a brand new fully charged battery on. Didnt fix the issue. Checked 2 fuses that are near (connected to) the disconnect switch - there was no break in the fuses. Found a small button and it seems to be pushed in (and tried to push it in further).

 

[Larry-NC]

Very unusual

On mine, the reverse polarity diodes break the connection to the battery which will also prevent the truck power getting to the lights/fans.

Most power centers use fuses, not diodes. Wondering what model you have...

That's very unusual. On most power centers the battery connections and low-amperage circuit fuses are connected on the same circuit board. The reverse polarity fuses only connect to the converter wires, to protect the converter if the battery is connected backwards. If the battery is installed backwards, incandescent lights will work, and fans and slideouts will run backwards.

 

[boondocking-FRF]

Most power centers use fuses, not diodes. Wondering what model you have...

That's very unusual. On most power centers the battery connections and low-amperage circuit fuses are connected on the same circuit board. The reverse polarity fuses only connect to the converter wires, to protect the converter if the battery is connected backwards. If the battery is installed backwards, incandescent lights will work, and fans and slideouts will run backwards.

X2

Thank you for the clarification.
There was a bit of mis-information posted above about the reverse polarity fuses.

 

[ian1643]

Battery problem

Take it back to the people who serviced it.

 

[Aussieguy]

Take it back to the people who serviced it.

it's not rocket science ... only needs about $10 -20.00 of basic electrical testing equipment

Take the time to learn how to diagnose
and how to MacGyver a fix while 200 miles from nearest service guy...
did you know you can bypass a dead breaker or disconnect switch in 5 minutes!


lots of videos on how to trace / measure 12v trailer battery faults

Use google if you need a quick video
"video how to test RV xxxxxxxxxxx with a multimeter"
replace the x's with whats suspected of being faulty

"video how to check RV battery wiring with a test light"

If you can change a battery ... you can learn how to test the basic circuit!
familiarize yourself with your components before leaving home!

autoparts stores carry basic trailer/rv electrical stuff... to at least get you out of trouble....
these stores are much easier to find while you are traveling
than looking for a tech that is available when you are stuck