Sudden loss of 12V

[Greg A]

Bobbie,

The negative from my battery goes straight to the frame on the 19, about a 3’ run easy to follow. Many times those get loose or crappy.
On the 17b it was similar only batteries were on the rear and the ground wire went straight to the frame from the battery and was causing similar electrical problems to yours. When I reworked it the electrical issues resolved.
I have no exposure to the 15, but I’m assuming it is similar setup to the 17...
Since you had power restore when hooked up n towing, then cut out again when at home, I’d not think it’s a fuse, but stranger things have happened and they need to be checked as well.

[Bobbie54]

Originally Posted by Greg A

Bobbie,

The negative from my battery goes straight to the frame on the 19, about a 3’ run easy to follow. Many times those get loose or crappy.
On the 17b it was similar only batteries were on the rear and the ground wire went straight to the frame from the battery and was causing similar electrical problems to yours. When I reworked it the electrical issues resolved.
I have no exposure to the 15, but I’m assuming it is similar setup to the 17...
Since you had power restore when hooked up n towing, then cut out again when at home, I’d not think it’s a fuse, but stranger things have happened and they need to be checked as well.

I think it has to be a loose wire since it went on once without being hitched up and then went out again.

[Bobbie54]

Originally Posted by padlin

My 2014 did not come with a battery line fuse, at least not till I added one, just the little cube breaker, which I think is 50A. You can see it in Bobbie's pictures. The rectangle cube with the two threaded posts and nuts.

OK- started testing.

To summarize so far:

2 12V batteries in parallel, both fully charged
12V works when car is hitched up and running
12V works intermittently (mostly not) when not hitched up to car

I tested two things just now: the little cube breaker. Not sure about setting on the multimeter but both sides read 3.3. You can see my meter setting in the pics. Also tested the 12V plug, as long as something was in it to complete the circuit (used the tested)

it read 3.3 also. (It read 12.8 with the tester when the 12V was on.)

I still need to trace the black wire back from the battery but it goes into one of those plastic wire covers with the red one so haven't gotten far.

I'm thinking the shutoff switch was where the red wire is spliced so will undo all that tape and see what I have there but wanted to make sure I was setting the multimeter the right way.

[Bobbie54]

Originally Posted by MyronL

This little breaker hidden under my dinette seat failed on me. I replaced it with one from an auto supply store.

You've got that spliced red wire, too, I guess it comes that way?

[Bobbie54]

If I find the ground and test it should it read the 12.8 if I bridge between the wire and the ground?

[padlin]

yes, as long as you are on DC.

[Bobbie54]

I think I found the ground; a line off the main one goes to the frame and is attached firmly by a well-rusted screw. No wiggle there. I'll work back from the battery taking off the covering to make sure no splices as I don't know how that would give me an intermittent connection. What about the 3.3 volts by the 12V socket?

[padlin]

Rust isn't a great conductor, might be worth cleaning that up or at least ohming out the connection.

[Bobbie54]

Finally got the mattress out so I could access the fuse panel and converter box.

The two 40 Amp fuses are not labeled. I did not (yet) pull them to check as I figured I'd ask here first what they are.

I have no idea about any of the wires back there. Nothing seems loose, that's all I can say.

I have not yet tackled the ground wire which seems solid but plastic covers keep me from checking whether there are splices somewhere that might be loose.

[Vermilye]

Originally Posted by Bobbie54

Finally got the mattress out so I could access the fuse panel and converter box.

The two 40 Amp fuses are not labeled. I did not (yet) pull them to check as I figured I'd ask here first what they are.

I have no idea about any of the wires back there. Nothing seems loose, that's all I can say.

I have not yet tackled the ground wire which seems solid but plastic covers keep me from checking whether there are splices somewhere that might be loose.

They are called reverse protection fuses, and are there to protect the converter from having the battery (ies) connected backwards.

[Bobbie54]

Originally Posted by Vermilye

They are called reverse protection fuses, and are there to protect the converter from having the battery (ies) connected backwards.

Thanks. At least I know that isn't the problem since everything worked for at least part of the time.

[Bobbie54]

Originally Posted by Bobbie54

OK- started testing.

To summarize so far:

2 12V batteries in parallel, both fully charged
12V works when car is hitched up and running
12V works intermittently (mostly not) when not hitched up to car

I tested two things just now: the little cube breaker. Not sure about setting on the multimeter but both sides read 3.3. You can see my meter setting in the pics. Also tested the 12V plug, as long as something was in it to complete the circuit (used the tested)

it read 3.3 also. (It read 12.8 with the tester when the 12V was on.)

I still need to trace the black wire back from the battery but it goes into one of those plastic wire covers with the red one so haven't gotten far.

I'm thinking the shutoff switch was where the red wire is spliced so will undo all that tape and see what I have there but wanted to make sure I was setting the multimeter the right way.

Shouldn't these read 12.8? Since it is the 12V charger? (I know 3.3 is sometimes found in circuits.) And if they should be 12V, what would cause a drop in voltage?

[padlin]

The black lead of the meter needs to go to ground while the other goes to one side of the breaker, is that what you did?

[Bobbie54]

Yes, I used a bolt in the seat compartment as the ground; I assume it goes to the frame.

[padlin]

If you only show 3.3 volts, the bolt may not be a good ground. Isn't there a grounding bolt on the back of the converter?

[Bobbie54]

I got the same for that little fuse with the two screws and the 12V plug.

[arniesea]

Originally Posted by Bobbie54

Thanks. At least I know that isn't the problem since everything worked for at least part of the time.

Did you check the battery shut off switch? Mine failed but it was confounding because what failed was one of the little copper leads that the positive wire from the battery connects to was loose. So it would allow power to the system but jiggled in another position all the 12v systems shut off. Very similar symptoms to what you are describing. In effect, it was like the battery shut off switch was in the off position even when it wasn't.

The workaround until I could replace the switch was to just disconnect the two leads from the switch then connect them to each other directly. This is easy with a small nut and bolt connected through the two eyes on the end of the leads.

You only need the disconnect switch to work for long term storage if the trailer is not connected to shore power, so you can go a long time with the leads connected to each other directly. We went over 1,000 miles that way.

[Ron in BC]

Prior to 2015 ETI, at least on the 19, ran the battery negative to a screw on the frame, used the frame as a ground for about 18" and then had a ground cable screwed to the frame and it went up to the negative buss on the converter.

Negative grounds screwed to the frame rust and are poor conductors.

You could use a long jumper cable from the battery negative to the converter negative and see if that makes a difference. You could also measure the resistance between the same two terminals

Ron

[Rossue]

Had to run a longer ground cable when I raised the dinette floor. The original connection to the frame was corroded. Won't be surprised if that is the problem.

[Bobbie54]

Originally Posted by arniesea

Did you check the battery shut off switch? Mine failed but it was confounding because what failed was one of the little copper leads that the positive wire from the battery connects to was loose. So it would allow power to the system but jiggled in another position all the 12v systems shut off. Very similar symptoms to what you are describing. In effect, it was like the battery shut off switch was in the off position even when it wasn't.

The workaround until I could replace the switch was to just disconnect the two leads from the switch then connect them to each other directly. This is easy with a small nut and bolt connected through the two eyes on the end of the leads.

You only need the disconnect switch to work for long term storage if the trailer is not connected to shore power, so you can go a long time with the leads connected to each other directly. We went over 1,000 miles that way.

No battery shutoff switch.