Help with lack of 12V power...Updated

[JustLabs]

I de-winterized our trailer,and we took it out for the first time since last fall. Everything was working normally in the driveway.

Got unhitched and set up at the campsite. Opened the door and heard the propane detector going off. Thought that was weird and before turning on any lights or appliances sniffed around for a leak.

Didn't find anything so I flipped on the lights. The lights were very dim. I checked the battery level with the little dummy sensor used to check black/gray water levels.

All the lights on the panel flickered a couple times and went blank. I had lost all 12V power in the trailer. The only thing left working was the landing gear which is wired to a 50A circuit breaker and then to the battery. The landing gear went up and down with no sign of low/dead batteries.

I plugged into shore power and everything started working properly. I spent some time checking everything I could think of trying to work out the lack of 12V in the trailer.

I was having some coffee Saturday morning when I started to hear a clicking sound. I traced it to the 50amp circuit breaker connected to the landing gear. It tripped and reset about a dozen times and stopped. Checked the landing gear and now they don't work.

Got home last night and started digging around again. I've tested and re-tested everything I can think of. The only thing I've found was the bad 50A circuit breaker. I replaced it this morning and the landing gear is again working correctly

The converter is putting out the correct voltage. All fuses and circuit breakers test good with a test light,and multi-meter. The batteries show correct voltage and test good with a battery tester. Battery connections are clean and tight.

Everything continues to work properly on shore power,and nothing except the landing gear works on 12V

At this point I'm stumped. If anyone can think of something I maybe missed,I'd love to hear it.

I'm going out shortly to pull down the underbelly plastic and see if there is a fuse or circuit breaker I can't see.

[2oldman]

JustLabs wrote:
I spent the morning tracing wires,and finally discovered the issue.

Thanks for reporting back.. and good job!

[wa8yxm]

It could be worse... One forum member in one of the forums I frequent had a terrible odor in his RV

Turns out when installing a wall the installer could not be bothered to use the proper length screws.. So he used a screw that was too long to bold the board to the floor.. It went through the board, through the floor, through the black tank............

[JustLabs]

I spent the morning tracing wires,and finally discovered the issue.

During the construction of my trailer,the person that installed the subfloor failed to notice the two 8ga. wires laying on top of the frame.

The subfloor was installed over the wires. Over the course of 10 years it looks like the positive wire finally broke/shorted out from being pinched between the frame and subfloor.

I ran new wires from the converter to the batteries and we're back in business.

Thanks to all that offered advice.

[Old-Biscuit]

opnspaces wrote:
Have you used your meter to check for 12v power at the distribution panel? If you pull the cover off the panel you should find the battery positive and negative connections. See if you have battery voltage at the panel. Don't just look for 12 volts. If your batteries read 12.67 volts you should also see 12.67 volts at the panel.

Also check and make sure you have a good ground connection at the battery and at the frame.

Do this test without shore power.....

Battery tests good.....runs landing gear......in-line battery protection fuse good

SO it would appear issue is between battery in-line fuse and converter


Strange thing was the 'LP Detector' low battery alarm going off??

[opnspaces]

Have you used your meter to check for 12v power at the distribution panel? If you pull the cover off the panel you should find the battery positive and negative connections. See if you have battery voltage at the panel. Don't just look for 12 volts. If your batteries read 12.67 volts you should also see 12.67 volts at the panel.

Also check and make sure you have a good ground connection at the battery and at the frame.

[BFL13]

As others have noted, you seem to have an "open" on the wire path from converter to battery. You say the battery fuse is ok. So there has to be another open in that path. You say it is not the disconnect switch. So what does that leave? Perhaps a loose connection at the battery wire lugs on the fuse panel?

The jacks and slide have direct connection to the battery so they will work even if the battery juice can't get to the fuse panel and be charged from the converter (also on the fuse panel.)

You could try to run the jacks from the converter (shore power needed) with no battery to see if there is indeed an open in the path. You take the battery wires off and clamp the two red wires together that were on the battery pos post so there is still a path from converter to jacks.

You need to find the open with a voltmeter at each end of every item in the path till you no longer get 12.x battery voltage. That's your culprit.

[2oldman]

very good

[JustLabs]

2oldman wrote:
How did you treat your batteries over the winter? Were they kept charged? Do they have enough water? Are they old?

I know you said you checked them, but they can do funny things.

They're a year old this month. They're kept on a Noco Genius battery maintainer. Water is correct level.

[2oldman]

How did you treat your batteries over the winter? Were they kept charged? Do they have enough water? Are they old?

I know you said you checked them, but they can do funny things.

[JustLabs]

Old-Biscuit wrote:
Follow battery positive cable that goes to converter.
Close to battery will be a In-line fuse OR DC Circuit Breaker ---most likely 30A or larger
It has tripped......therefore no DC from battery when not connected to shore power
When on shore power converter is supplying DC...but no charging of battery

You're correct,there is a 30 amp fuse inline near the batteries. It tested good this morning. Replaced it and the second fuse also tested good. Still no 12V power.

[Old-Biscuit]

Follow battery positive cable that goes to converter.
Close to battery will be a In-line fuse OR DC Circuit Breaker ---most likely 30A or larger
It has tripped......therefore no DC from battery when not connected to shore power
When on shore power converter is supplying DC...but no charging of battery

[Crazy_Ray]

bad battery

[JustLabs]

Almot wrote:

JustLabs wrote:
I'm going out shortly to pull down the underbelly plastic and see if there is a fuse or circuit breaker I can't see.

No need to pull down the underbelly. 12V fuse box is often bolted to the frame outside, i.e. below the underbelly, somewhere in front end. Usual $3 residential box with holes and all. With automotive resettable fuse. Could've gotten wet, rusty, mice got to wires, or the fuse tripped.

The resettable circuit breakers are in the front storage near the batteries.

[Almot]

JustLabs wrote:
I'm going out shortly to pull down the underbelly plastic and see if there is a fuse or circuit breaker I can't see.

No need to pull down the underbelly. 12V fuse box is often bolted to the frame outside, i.e. below the underbelly, somewhere in front end. Usual $3 residential box with holes and all. With automotive resettable fuse. Could've gotten wet, rusty, mice got to wires, or the fuse tripped.