2023 23bhe 12v does not work off batteries only

[Deveasey]

12v system does not work off batteries.

Info: 2023 23bhe
Dual batteries wired in parallel measured 12.3 - 12.9 volts

problem: the 12v system does not work when on just batteries.
works on shore power and when connected to the truck.

12v lights, Jack, slide out, monitor panel, radio - all powerless.

what I have tried / checked
all blade fuses in the breaker panel.
all breakers in that breaker panel
the fuse to the Jack
the two fuses near the front.
the fuse behind the battery switch.

i traced the 12v from the batteries to the fuse for the Jack and I get 12+ volts (12.9 I think) keeping the black terminal on the battery and using the red to poke.

there is a self tapping bolt and I measured 10v from the black terminal to that bolt and the frame.

What else should I test / check?
what am I missing?

yes the switch was on.

background: the camper was sitting hooked up since November as a dry cabin for the winter ski season.

does anyone know how to get the diagram?

I have completely wired boats but I’m new to RVs

[TenOC]

12v system does not work off batteries.

Info: 2023 23bhe
Dual batteries wired in series measured 12.3 - 12.9 volts

If in SERIES you have 24 V not 12 V. No telling how many fuses are burnt out.

[ncitro]

If in SERIES you have 24 V not 12 V. No telling how many fuses are burnt out.

I assume he has dual 6v batteries in series since he is reading 12.9V.

[Deveasey]

If in SERIES you have 24 V not 12 V. No telling how many fuses are burnt out.

Thanks for pointing this out. I mis-spoke and updated the post.

[ncitro]

12v system does not work off batteries.

Info: 2023 23bhe
Dual batteries wired in parallel measured 12.3 - 12.9 volts

problem: the 12v system does not work when on just batteries.
works on shore power and when connected to the truck.

12v lights, Jack, slide out, monitor panel, radio - all powerless.

what I have tried / checked
all blade fuses in the breaker panel.
all breakers in that breaker panel
the fuse to the Jack
the two fuses near the front.
the fuse behind the battery switch.

i traced the 12v from the batteries to the fuse for the Jack and I get 12+ volts (12.9 I think) keeping the black terminal on the battery and using the red to poke.

there is a self tapping bolt and I measured 10v from the black terminal to that bolt and the frame.

What else should I test / check?
what am I missing?

yes the switch was on.

background: the camper was sitting hooked up since November as a dry cabin for the winter ski season.

does anyone know how to get the diagram?

I have completely wired boats but I’m new to RVs

Only 10V to the bolt in the frame sounds like your issue. That bolt should go from the self resetting circuit breakers to make the whole frame a "good" negative return point. If you only have 10V there, follow that wire up to the self resetting breakers and see what you have at the other end of the wire, and work through all the way to the negative battery terminal. You will find a place where you are dropping voltage somewhere.

[Deveasey]

Only 10V to the bolt in the frame sounds like your issue. That bolt should go from the self resetting circuit breakers to make the whole frame a "good" negative return point. If you only have 10V there, follow that wire up to the self resetting breakers and see what you have at the other end of the wire, and work through all the way to the negative battery terminal. You will find a place where you are dropping voltage somewhere.

I don’t see where the negative goes, it goes into a big bundle and up into the belly. This sounds like a corroded negative. But where?

[Deveasey]

I have 12.9v on both bolts here.

[ncitro]

Thats your auto reset circuit breaker for +12V. I agree sounds like a bad line to the frame. You will need to trace that wire from the frame to its connection point, possibly pulling down the coroplast if you cannot see where it goes. Usually you can pull the screws out in the corner you are working in to see whats going on.

[Deveasey]

Thats your auto reset circuit breaker for +12V. I agree sounds like a bad line to the frame. You will need to trace that wire from the frame to its connection point, possibly pulling down the coroplast if you cannot see where it goes. Usually you can pull the screws out in the corner you are working in to see whats going on.

dang ok, I was trying not to get into this part. I will dive into it in a few days when the rain stops.

[ncitro]

Sorry, I do not have first hand experience with the travel trailer, but I am almost sure in the fifth wheels the wire from the frame goes directly to the battery negative post, unless you have the Furrion battery monitor with shunt:

[TenOC]

You measure 12.9V from the "bolts" to the battery or the FRAME??????? If only to the negative battery post, and not the frame, you have a problem with the negative wire to the frame.

[Deveasey]

Sorry, I do not have first hand experience with the travel trailer, but I am almost sure in the fifth wheels the wire from the frame goes directly to the battery negative post, unless you have the Furrion battery monitor with shunt:

I think I do have this monitor and I’m pretty sure there is a shunt mounted. I’ll report back what I find in my next adventure

[ncitro]

If you do, then the negative should go from the batteries to shunt and the shunt to the frame. Then frame to that bolt. Odds are your connection at the shunt.

[Jlawles2]

Double check both of the negative post on you batteries for corrosion. You have good voltage there as you say, then work down the negative line from there.

Ensure there are no protective plastic washers in use anywhere or caps over any screws or plugs.

[Deveasey]

So an update for tonight’s attempt
i found one rusty negative terminal so I pulled and cleaned all battery terminals.

I pulled a panel and found the furrion battery monitor shunt. But that is where is ended. I can’t figure out how to get to it.
any ideas?

the other side is a wall outlet next to the bed. It would make sense that this is an access panel but I don’t see a way to remove it