12V issue on 3400RL 2011

[Emorin]

Following a Power outage, I found out that I have no 12V going inside my 3400RL 2011. Once electricity is back everything is working well. I Did check all my fuses, breaker, and I tried a new 12V battery of course, I checked my ground connexions also. And found nothing. After some discussions with camping friends... my main hypothesis is an issue with the converter. How can I check this and where it is located. Beside my 12V battery I have a kind of control or may this is the converte, I am not sure, and I can see a kind of relay which is flashing when I connect my 12V battery.
I read also it could be behind my fuses panel? If this is there, then what is the board I have beside my baterry.

Note: How can added picture...It may be a strange question but I am new here I am not able to see any pictures on all post I saw, and neither I can't see how to add one. I saw member photos but when I make a search it brings me again to all post...??

Etienne M

[Carl n Susan]

Let's make sure I understand the issue(s).

• With 120V shore power: all the 12V works.
• With NO 120V shore power; none of the 12V works.

This tells me the converter (which takes 120V to produce 12V) is working with shore power. Lacking 120V, the battery should be supplying all the 12V you need. Therefore you have a problem somewhere along the 12V system between the battery and the converter.

The 12V flow from the converter to the batteries is pretty straight forward. As others have pointed out, here are the places to look. All connections should have 13.5 +/- Volts if the converter is working.

• The converter is part of the power distribution panel -Ensure the CB for it is On
• There are Reverse Polarity Fuses on the converter which protect against connecting a battery backwards. - Ensure they are not blown.
• Check the output voltage at the converter. - it should be in the 13.5V DC range.
• The power then runs to the Disconnect Switch in the Convenience Center. - Ensure the Red Key is in the position where it can *NOT* be removed. If removed, this interrupts the power charging the battery. The Disconnect Switch is not know to fail, but you can remove it to check there is power in and out of it just to be sure.
• The power next flows to the group of 50 amp self-resetting CBs behind the battery. We all know about the one that hiccups and interrupts the hydraulic system. That one also passes power to/from the converter and batteries. You want to check it and it's brother (it is in the current flow to the battery) to ensure there is 13.5V on *EACH* side of the CB.
• The last connection is the one from the 50 amp CBs to the batteries. Ensure you have clean connections and the cables are not corroded (watch out for internal corrosion under the shrink wrap).

Somewhere along this path there will be the problem. A simple VOM should find it. I hope this helps.

The converter is part of the power supply system That is where the 12V fuses and 120V circuit breakers are located. The power center in a 3400RL is unique in that Montana put it in the bathroom. However from your description (assuming I interpreted it correctly) the converter is not a your problem.

I can see that you figured out how to Post pictures here on the MOC By the way, that is a nice picture, but not one of your power center. That is the "brain" for the remote control system which is located in the front battery compartment.

Go to https://www.montanaowners.com/forums...ad.php?t=70323 and read posts #8 and #25.

If you upload the pictures to the MOC, subsequent viewers can blow them up to a larger, more viewable size. And you will avoid the problem where the picture hosting site decides to no longer allow web forum access (Tinypic, Photo Bucket, etc.)

[twindman]

Couldn't this just be the key turned the wrong way in the convenience panel outside?

[BB_TX]

Originally Posted by twindman

Couldn't this just be the key turned the wrong way in the convenience panel outside?

Certainly could be. And is probably the most common culprit, with a bad 50 amp auto reset circuit breaker being second. But could also be any of the things Carl mentioned.

[Emorin]

You means the red key that Carl talked about?

[Carl n Susan]

Emorin: here is a link to a Thread that has pictures of the 12V red plastic covered self resetting circuit breakers located near the battery,

https://www.montanaowners.com/forums...ad.php?t=78438


As Bill noted above, the Red Key is the most common cause of 12V power loss. The self resetting 12V CBs are a close second.

[Emorin]

Thanks to all! Quite interesting the information found with the latest link, I will need to look at it deeply next week-end to better understand. I did not figure out that behind those red plastic it was self-resetting CB!

Until that time, I am pretty sure I found my problem. I am not quite proud of me but you have clearly taught me something tonight... the problem was this famous red key, it was not at the good position! Now I know and it seems pretty obvious.
I love my fifthwheel but it gets me out of my habits clearly

Thanks again
Etienne

[BB_TX]

We have all had those embarrassing moments where we look around to see if anyone was watching. Such as unhitching and forgetting to lower the tailgate before pulling forward (bent tailgate). Or blowing 5 consecutive fuses to my front electric jacks before realizing I had forgotten to loosen the tightening screws on my after market stabilizers.

[twindman]

Even tho I know about the red key, I still get caught. I never turn it, but sometimes the dealer does and I get home and things don't work!

[Carl n Susan]

I put red gorilla tape over the red key with a tag that says "Don't Touch". I do have a true disconnect switch near the batteries.

[richeyb]

I had the odd case of my red key failing. After checking power supplies along the system I found my red key had failed and would not connect power when turned. To get power I took the key housing apart and connected the two wires together eliminating the key. This allowed us to continue camping wait for a new key unit to arrive.
Side question…why do we ven need the red battery disconnect key in the system??

[AZ Traveler]

Billy,

I would leave your red key bypassed and install a total battery disconnect at your battery bank.

With the red key turned off there are still items powered which will run down your batteries during storage.

[Carl n Susan]

What AZ_Traveler said above ^^^^^^^^^

[BB_TX]

The only time I can see the disconnect of any real use would be if you were on shore power, your converter running, and you wanting to, say, replace your battery. With the converter running and your battery positive cable disconnected, that cable would still be hot because the converter would be trying to charge the battery. That cable touching ground would cause an immediate short. A disconnect switch at the battery would address that issue.

[jimcol]

After learning how worthless it was I formed the opinion it was sales fluff. Visiting many RV shows over the years I learned most sales people didn't even understand the short comings of it.