12 volt question!! - Montana Owners Club

Sdgood1 · 05-01-2019, 04:16 PM

OK, Power flush fixed!! broken vacuum breaker under bathroom sink!!!
We took our first short trip in our new to us 2014 3150RL. Almost everything went great!! Here's the question. The TV, DVD, surround sound are located in the rear DS. Wanting to be able to run these items off of 12V so I don't have to run genset all the time, when i want to watc TV. There is NOT a cigarette lighter access anywhere in the area. So in my infinite wisdom figured I could pull 12V power that is going to the puck light over computer desk, hard wired in a 500 watt inverter to run all these items (190 watts combined) Worked great until I tried it without being plugged in for a short period of time (on trip of course) it seems that the inverter is shutting down on low voltage?? Guessing maybe end of line and voltage has dropped that low?? Made sure nothing else on that circuit was on, etc. Should I just go ahead and run a dedicated wire ????? I'm sure somebody else here has tried the same thing. ALL advice appreciated.
The TV and DVD player in bedroom works off a 100 watt cigarette lighter inverter with no problem (only 85 watts) ??????????

**AZ Traveler** · 05-01-2019, 05:00 PM

Steven & Denise,

You are going to have a lot of line loss running 12 volt wiring. Will work for the small puck lights only drawing a few watts but not for a 500 watt inverter. I would install a little bigger inverter up in your battery compartment and then run 110v back to your TV and other things. Get professional help if you are not comfortable.

daveinaz · 05-01-2019, 07:18 PM

I think most inverters recommend 0-4 awg cable and a length of no more than six feet of it from the battery to inverter.

BuilderBob · 05-01-2019, 09:40 PM

Quote:

Originally Posted by Sdgood1

OK, Power flush fixed!! broken vacuum breaker under bathroom sink!!!
We took our first short trip in our new to us 2014 3150RL. Almost everything went great!! Here's the question. The TV, DVD, surround sound are located in the rear DS. Wanting to be able to run these items off of 12V so I don't have to run genset all the time, when i want to watc TV. There is NOT a cigarette lighter access anywhere in the area. So in my infinite wisdom figured I could pull 12V power that is going to the puck light over computer desk, hard wired in a 500 watt inverter to run all these items (190 watts combined) Worked great until I tried it without being plugged in for a short period of time (on trip of course) it seems that the inverter is shutting down on low voltage?? Guessing maybe end of line and voltage has dropped that low?? Made sure nothing else on that circuit was on, etc. Should I just go ahead and run a dedicated wire ????? I'm sure somebody else here has tried the same thing. ALL advice appreciated.
The TV and DVD player in bedroom works off a 100 watt cigarette lighter inverter with no problem (only 85 watts) ??????????

An inverter need bigger wire than what your puck lights use and need to be hooked directly to the battery with in 4'

BB_TX · 05-02-2019, 07:55 AM

Remember, it takes ten times the current at 12 volts as it does at 120 volts for the same power in watts. Watts = volts x amps. So 120 watts = 12v x 10 amps = 120v x 1 amp. Plus there are some losses in an inverter so that you don't get the full power out that you put in.

Sdgood1 · 05-02-2019, 08:55 AM

Great info, live and learn. Thanx everybody for the input. IF we like the rig, will go ahead and add solar and bigger inverter.

cgeis48 · 08-17-2019, 02:11 PM

One of the slides in my Monty has an electrical problem. Intermittently, the coach ceiling lights dim when I switch on the overhead reading lights in the recliner slide-out. Sometimes it all works as normal but other times the coach ceiling lights dim and a 12V fuse blows. Replacing the fuse sometimes fixes the problem but then it will all happen again in a day or days later. I've replaced the reading lights and tested the 12V switches but the problem persists. Where else should I be looking to find the source of the problem?

**Carl n Susan** · 08-17-2019, 02:20 PM

Which 12V fuse is blowing? I assume there are separate fuses for the ceiling lights and the reading lights in the slide out. But perhaps not. Since it is the reading lights that seems to cause the problem, take a good look at the junction box outside under the slide. They have a tendency to accumulate water and cause problems.

BB_TX · 08-17-2019, 04:03 PM

If no water in the box then look for a loose or frayed wire in the harness under the slide that has to flex every time the slide goes in and out. Sounds like an intermittent short.

jcurtis934 · 08-17-2019, 04:13 PM

Given that it is 2020 model, more than likely there are no junction boxes under slides and you will find the 12vdc line as a black rubber covered stranded cable at the rear end of the slide. So what they do is transistion from normal 12vdc wiring near the back of the slide, out through a hole in the slide floor, across the gap in the folding line keeper you see under there, into the back corner of the rv where it again transistion from the rubber covered cable back into normal 12vdc wiring. You may be able to find the inside transistion hookup to check it, but the rear of the rv transistion will mean dropping the cloroplast bottom to find the other end. Good luck with your hunt for the bad connection.

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