12 volt system failure - Montana Owners Club

Petmoose · 10-09-2018, 12:58 PM

The 12 volt system will not work inside. The lippet jacks work. When I am plugged into shore power everything works. The fuses for the batter in the converter are ok. Does anyone have a clue? Thanks

Lenny K · 10-09-2018, 01:19 PM

Is the battery cutoff turned on in the convenience center?

Petmoose · 10-09-2018, 01:36 PM

Battery disconnect switch is off. Thanks

**DQDick** · 10-09-2018, 01:38 PM

How about a bad battery?

Petmoose · 10-09-2018, 02:11 PM

They show good. I have 2 - 6 volts. Thanks

beeje · 10-09-2018, 06:22 PM

Back to the battery disconnect switch. There has been some confusion about that. If you can remove the red key, then power is cut off from the batteries going to the converter. Just making sure.

If that checks out ok, take the cover off the converter/breaker panel and get in there with a volt meter and start checking for voltage. While you are in there (WITH THE BATTERIES AND SHORE POWER DISCONNECTED) check the tightness of all the terminal lugs that clamp all the wiring in place. Sometimes they are not tight from the factory or loosen up over time.

Petmoose · 10-09-2018, 06:31 PM

Thanks. I will Check it out and will report back.

lensnel · 10-10-2018, 02:40 PM

If I am connected to shore power and the battery disconnect switch is in the "can't take out the key" position, should the battery charge be maintained by the shore power?

**AZ Traveler** · 10-10-2018, 02:44 PM

Quote:

Originally Posted by lensnel

If I am connected to shore power and the battery disconnect switch is in the "can't take out the key" position, should the battery charge be maintained by the shore power?

Yes, for the battery to charge the battery switch needs to be on (when you can't take the key out).

Petmoose · 10-10-2018, 08:53 PM

Thanks beeje for your explanation. That solved the problem. I do not remember ever turning the red key so that it could be removed but when
I checked it that was the problem. Thanks to all for the help. I feel kinda dumb for not double checking that in the first place.

lensnel · 10-10-2018, 09:15 PM

Wow, Now I know why I joined this group! THank you Beeje and Petmoose for your help!

beeje · 10-11-2018, 05:25 PM

No thanks needed. That's why we are all here on this forum and others to get the answers we are looking for from each other. We all have a vast wealth of info inside us that is worthless to keep to ourselves.

shovelhead86 · 10-11-2018, 08:35 PM

I had a similar problem and after some searching with a multi meter and some advice from fellows on here I found the problem to be a bad 50 amp auto circuit breaker Located just above the batteries. I replaced it with a 80 amp and problem solved. Just use your volt meter and check where you have 12 volts and where it does not and should.

Petmoose · 10-17-2018, 02:11 PM

I had replaced the 50 amp with 80’s last year and have never had an issue since with the breakers tripping. Thanks

whutfles · 10-17-2018, 02:35 PM

My 2010 Montana kept momentarily tripping the 30 amp breaker on the slides. The dealer installed a 2nd 30 amp breaker beside the first one so that if one trips, the other carries the load and that solved the issue. They didn't want to replace my one 30 amp breaker with a 50 amp breaker as they didn't think the wire was good for that load.

beeje · 10-17-2018, 04:25 PM

That's the main reason why I have not upgraded to the 80 amp beaker. Just like in your house, you should never upsize a breaker just because it keeps tripping.

rohrmann · 10-17-2018, 07:33 PM

On our rig, the cable from the batteries to the auto reset breakers is #4 strand copper, and this is more than able to handle the current through one of those 80 amp breakers. On older rigs, they may have smaller cable, and in those cases, maybe the 50 amp breaker is a better option. I would suggest getting a 50 amp breaker that is built like those 80 amp breakers, as they probably will hold up much better than the cheap 50 amp breakers that come in these rigs.
https://www.amazon.com/Bussmann-CB18.../dp/B0024JHQ02

paulinbaja · 10-17-2018, 08:31 PM

Don't feel dumb. That is the reason for this blog.

paulinbaja · 10-17-2018, 08:33 PM

Very dangerous, neither breaker will trip. But if one did the other would trip immediatly.

DebNJim B · 10-18-2018, 05:43 AM

I had a similar problem and the red disconnect was on. But if you have a residential fridge and an inverter there may be another cut off switch near the battery. In mine that cut off the power going to the converter and charging the battery. I first discovered it when the fridge wouldn't run on battery power.

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