Interior lights on 12V

[RVnewbie]

Hello!

Very excited to share, that after 10 years of lurking fiberglass RV forums, classifieds, and new trailer company websites, I finally got my own!

I am super happy with my find, a lil’ Bigfoot in great condition.

However, I thought I should be able to run the original 3 way Dometic fridge off of propane and still use the 12V battery for inside lights/electrical plug-ins but that doesn’t seem to work. Is that not possible? Is there a switch I should be trying to find? The lights/plug ins work when connected to shore power.

2nd question; suggestions for where another power source could be hidden? Even with the battey disconnected the lights above each bed and the “porch” light still work! I can’t find the power source!

So many mysteries and I have no idea where to start!
I have very little knowledge so any recommendations need to be very explicit, lol! I have a feeling I’ll likely have to take it in for servicing ....

[John in Michigan]

Dana, after a ten year search congratulations on your new to you Lil Bigfoot! Great camper.

[John in Michigan]

In response to your first question, yes 12 volt lights inside the trailer should work without shore power if there is a 12 volt battery. Electrical plug-ins should work if they are 12 volt or USB, AND if they wired back to 12 volt power panel (via the converter or 12 volt fuse panel).

Not sure how to answer your second question...

EDIT: Is the battery located on the tongue? Maybe look for a burnt out fuse. There could be an inline fuse under the front bench. Also check the fuses in the converter box.

[South Coast Stu]

Are you saying that the lights work off the 12V battery but when you turn the fridge on with propane they stop working? FYI - most fridges use a little 12V even when they are running on propane (to power the control board).

Yes, there can be more than one battery. I have one on the hitch and 3 inside a compartment in the trailer. Keep looking!

Congrats on the new trailer!

[RVnewbie]

Thanks Stu and John,

Thus far the only battery I can find is under a bench, I have checked every cubby! There is none on the tongue. The 3 lights mentioned EVEN when I disconnect known battery, so there must be another source somewhere

I have checked all the fuses I can find, but I do not know what a converter box looks like?

[South Coast Stu]

What year is your Lil' BF?

I had a light in the canopy of of a pick-up that was powered by AA batteries (in the unit itself). Maybe?

PS: When most converters are on they will make a slight buzzing sound.

[John in Michigan]

The converter is the "electrical power box" that contains 110 volt AC circuit breakers to protect the 110 volt AC circuits (e.g., for outlets), 12 volt DC fuses, and an AC-to-DC power converter. The shore power cable powers it. It usually in one of the cabinets and has a front panel for accessing the circuit breakers and fuses.

------------------------

The lights that work even with the battery disconnected may contain internal AA or AAA batteries.

[RVnewbie]

It is a 1987.

I am thinking the 3 lights, which are newer LED, may be small battery powered....but I disconnected the 12V battery and the water pump still runs, so there must be another power source somewhere.... I have checked everywhere!

Does the converter box look like a house fuse box?

[RVnewbie]

Thanks John, you posted just before I did. Thanks to you both!

[South Coast Stu]

How do you disconnect the battery? Are you plugged into shore power when you try this?

Here's an old post that has some good info. Franswa is very helpful. There is a pic of the load center that John described - AC breakers, converter/charger and DC fuses https://www.fiberglassrv.com/forums/...ing-75507.html It should have a brown cover and be located on the face of the drivers side bench. Twist the little black "thingy" 90 degrees and it should open.

Sure there isn't an extra battery on the tongue?

[RVnewbie]

I just disconnected the black (negative terminal), no shore power.

[South Coast Stu]

I'm still not understanding if the lights work until you turn the fridge on propane (and it works fine?). What model fridge?

However, I thought I should be able to run the original 3 way Dometic fridge off of propane and still use the 12V battery for inside lights/electrical plug-ins but that doesn’t seem to work. Is that not possible? Is there a switch I should be trying to find? The lights/plug ins work when connected to shore power.

Did you find the load center yet? It sounds like there has got to be another battery somewhere. If not, you have discovered how to make electricity out of thin air Don't sell that trailer!

Here's a post from trouble I had with my fridge and 12V power. I finally found a fuse that was tucked away. https://www.fiberglassrv.com/forums/...rce-83415.html

It really sucks sometimes that there are no factory wiring diagrams that come with these trailers

[RVnewbie]

Hi Stu

No the main inside trailer lights only seem to work on shore power. When I have the fridge on propane, it was my assumption that the lights would run off the 12V battery- but no such luck. I’m not sure of the model #- will have to get back to you, it’s the original dometic though.

A separate mystery is the 3 lights and water pump that seems to work on by there selves lol.

I found the converter box, fuses are ok.

I have a service guy coming, I’ll let him figure it out!
Thanks everyone!

[AC0GV]

Originally Posted by RVnewbie

Hello!

....

Are you plugged into the tow vehicle at the time? If you have a seven pin that too can supply power.

That whole thing sounds like someone did a re-wiring job. Please let us know what he finds.

[Barb and Alan]

First of all, congratulations on your new trailer! As a Bigfoot fan myself, I am quite jealous that you found a little Bigfoot. As to the electrical question, I didn’t see anybody asking what would appear to be an obvious question and I’m sure you already figured this out but with these lights that are working when the battery is disconnected is the tow vehicle connected? Good luck on resolving it.

[AC0GV]

Originally Posted by Deadhead517

First of all, congratulations on your new trailer! As a Bigfoot fan myself, I am quite jealous that you found a little Bigfoot. As to the electrical question, I didn’t see anybody asking what would appear to be an obvious question and I’m sure you already figured this out but with these lights that are working when the battery is disconnected is the tow vehicle connected? Good luck on resolving it.

...the OP never came back. So I'm guessing that was the case.

[ZachO]

Fridge operation has nothing to do with other 12v operation. Because you've been mentioning the fridge on propane in relation to 12v electronics working, I'm assuming there's a misunderstanding about how the system should work that we should clear up. Can you explain the fridge/propane/12v system connection you're talking about?

Good work on the Bigfoot!

We'll get all this stuff figured out