12v battery problems 1990 Winnebago Micro Warrior (Toyota chassis)

[wahoonc]

Originally Posted by Icbigfoot

Hi Morich.

When I jumped the 2nd breaker, the line from the battery to the breakers got VERY hot instantly.

Still nothing at the 12V side of load carrier inside.

You have a helluva short somewhere.

It's time to start tracing circuits.

Aaron

[Morich]

Sounds like a dead/ definite short on the wire from the breaker on into the load center OR something in the load center.
If you go into the load center and take that wire on the top right hand side off. it will help tell you if it is the wire rubbed on metal somewhere or if the load center has a big problem inside.
See post 9 and the center picture that I marked in red and green? I recommend unplugging the RV from power and stay off anything on the left side where 110 is!
But if you take that wire loose at the load center and at the breaker, you might use the meter to look for ground on the loose wire!
Using the meter to test resistance from the wire to ground is better than making a new breaker trip too many times. It seems like tripping them too much can shorten their life. I've never proved it but it seems better not to trip them too many times!

But then I might wonder why the wire from the battery to the breaker would get hot instead of the one from the breaker to the load center? Any chance the breaker itself is getting grounded to metal right where it mounts? Any chance the breaker mounting screw is shorting to the metal right there?

[Icbigfoot]

Hi. I made sure there is no metal touching the breakers and checked the converter to double check the fuses and the connections, which all look good.

Here is my load center because I am not sure which wires to disconnect. Once disconnected, not sure what the next measurement should be.

Thank you so much!

[Icbigfoot]

Here si the pic of the load center.

[Morich]

Looks like they changed things a little bit, just to confuse us? Maybe Canadian and the drawing is US? Same thing but the voices sounds different!
Same things but looking different, so we can still do it.
There is a ground wire from the frame, etc. and it is the bare wire hiding at number 1! One thing to depend on is a bare wire should be the only bare one! Then there is a green wire at 2, connected to the same spot and that is likely ground for the load center.


Where we think there may be a problem is the black wire at 3. As long as you stay away from the 110 side, it is safe to disconnect this black wire and leave the end where it is not touching anything while you test. Not unsafe but it may spark some or trip the breaker if it hits metal like the side!
Is there any chance there will be enough slack to pull that black wire out toward you to see if it has rubbed bare where it comes in the back? If it's bare at some spot, I would tape it up good with several wraps of tape and try to make sure a different spot goes out the hole in back. Then put it back together there and the breaker and see if it works!

One thing to avoid is pulling the wire just a little so the bare spot if moved off the metal but waiting to give you trouble next time it moves a little! If you peek in and see black spots, be sure to fix it or it will come back to bite you when you really don't need trouble!

Then if you want to test with the meter for this wire shorted/ making contact with ground, you can take it loose at the breaker. that should leave you just a wire, loose at both ends. This lets you test ONLY the wire to make sure it is good without having anything connected at the ends to confuse things.
Using a meter set to test resistance(Ohms) you can put one meter lead on a metal ground like anything connected to the frame and the other probe on the wire.
The metal should not show any reading if the wire is not touching ground somewhere.

But I suspect you will get a reading and the lower that reading, the more solid the short to ground!

But if you get that reading, that means this wire is damaged somewhere between the breaker and the load center where you took it loose!
One good suspect to look at if you do find a reading is where this wire goes into the load center cover/cabinet backside!
There may a clamp where it goes through the metal or maybe a rubber grommet that has got loose or broken down to let the wire rub insulation off!

You may be able to peek behind things from the front to see what's happened but more likely you will have to take the load center out of the cabinet enough to look.
I might guess it will not be hard to spot as you seem to have a lot of power going somewhere and that probably means sparks and arcing!

It's a good news/bad news thing? Bad to have problems but the good part is the breaker is doing it's job and not letting the whole thing get hot enough to burn the RV!!!

[Icbigfoot]

Disconnected the black wire and was able to pull about 10 inches of the wire out to inspect. It looked new and clean. Put the olms meter on it (and on the ground) and got 0.00 reading.

I will pull the load center unit tomorrow to see if anything in the back is shorting. But I'm hesitant to attach the battery again to the breakers because it got so hot that it looked on its way to making a nice campfire.

Should there be any charge at the load center if I just leave the large red wire connected to the battery without connecting the battery also to the breakers? There appears to be no charge going through.

[Morich]

I'm beginning to think there may have been some changes made when the wires at the breakers were repaired. Those yellow connectors are not what we normally see and that may be messing our whole idea up if they changed some other parts or put the breakers back in different place.

I think I might not pull the load center out just yet, but do some testing to make SURE the wire at the load center is the same wire you are testing at the breakers!

The breakers and load center are not close enough together to reach both ends of the wire at the same time?
What I might do is look for a helper to either watch the meter after I got it hooked on the wire and the other probe on ground. Then I might go to the load center and touch that wire end to ground. If the meter is on the same wire as you touch to ground the meter should jump up with some reading!
I try not to press my wife's electrical training but she can tell me when the meter shows a reading!

I think you will have to find both ends of the wire that is making one get so hot and I'm against hooking power to it, until I'm sure!

[Morich]

I hate to think it but there is a big point that I've not been thinking about!
That black wire is not only the contact to carry power from the battery to the fuses but it also is a two way path that connects the converter, which is likely built into the back of the load center, back the other way to charge the battery!
If you are getting way too much current to make the wire get hot and the breaker is tripped/bad, one reason for that might be the converter is bad.
You've checked the wire for shorts to ground but the electronics of the converter may be the problem?

I wonder what you get if you leave that wire disconnected from the load center/converter, plug in the RV and check the lug where that wire came off?
With no load battery connected, it is likely to be somewhat high like 14 volts dc as it might be in "bulk charge" mode and ready to put out higher than normal current until it gets the battery near recharged and goes into a lower voltage output to keep the battery at float voltage.

See if you get something between 12 and 14-15 volts DC but I'm thinking it is the problem. Bummer!

[bigb]

You can troubleshoot a short by placing a 12 volt incandescent lamp in series with the line, in your case between the output of the auto-reset circuit breaker and the load wire. This will enable you to power up the shorted circuit without the CB opening and without the risk of anything getting hot. When the short is present, the 12 volt lamp will illuminate brightly, when the short goes away the 12 volt lamp will dim or go off completely (depending on what other loads are connected). This way you can wiggle wires around and disconnect stuff and when the lamp goes out you'll know what section has the short. You can also use a clamp on DC amp meter to see where current is flowing and where it is not, there will be little to no current once you pass the location of the short.