Too much voltage from bedroom 12v cigarette lighter port??

[versicom]

My multimeter is telling me that the 12v outlet in my 5th wheel bedroom putting out way too much voltage for about 2 seconds and them drops to the normal 12v. It's cooking any 12v device I plug into it. I have checked the socket and tried a new one so it's not the socket. The other 12v outlets in the trailer are all normal constant 12v. Anyone have any ideas? Do they make a 12v middle man conditioner that keeps voltage at 12v?

Weekend Warrior SLC 3705 (38' fifth wheel triple axel)

[Ramen]

If he had the wrong polarity, there would be a negative sign on his digital multimeter. I guess that could be a reason that things are cooking.

[christopherglen]

Is the polarity backward? That would explain smoking things.
Unless there is a second power supply, it is near impossible to have a higher voltage at this socket then the rest.

[versicom]

I am not using utility power. only battery power with my generator off. brand new batteries. I have the IOTA Engineering DLS-30. Again, all other 12v outlets work fine.

[time2roll]

Try unplugging from utility power and see if the spike goes away.
s/b same as battery terminal voltage at that point.

[versicom]

Thanks for the auto-range idea. that could be the cause of the short overload reading in the beginning. My FLIR meter has the ability to set the range static which I will try. Thanks Ramen, I will plan to disconnect everything and tone the line to see where it's running. The only explanation for burning up any 12v device I plug into it would be too much voltage/amperage considering I have tried two different 12v outlets (brand new). I will re-wire and call it a day. The toner should help with finding the line. Thanks again for everyone's input.

[Ramen]

Unplug all other devices, voltage test from that outlet. Next step I would do is to disconnect battery/power and see what is behind that outlet and trace the wire back. I would install fuses if they don't already have them.

[time2roll]

Autorange is easy to check by using same sequence testing on the battery direct.
Still does not explain stuff burning up.

My first thought was malfunctioning converter and no battery or battery disconnected.

[allcool]

versicom wrote:
what I mean by smoking is simply it burns up and 12v item I plug into the outlet.
Please give an example of what burned up...?

I am a computer engineer and quite capable with a multimeter. It should not be producing an overload when connected. It is clear to me that the outlet is getting to much voltage. I plan to rewire the socket which will not be an easy job as I do not know where the wires run. The owners manual came with no wiring schematics.

I tried to explain it to you.
Think this through, don't you find it strange that you only see this "spike" when you first connect the meter..? Ever wonder why there are no continuous spikes/high voltage readings...? Like I said above, its the auto ranging feature on your meter, momentarily showing overload while finding the correct range.

[versicom]

what I mean by smoking is simply it burns up and 12v item I plug into the outlet. I am a computer engineer and quite capable with a multimeter. It should not be producing an overload when connected. It is clear to me that the outlet is getting to much voltage. I plan to rewire the socket which will not be an easy job as I do not know where the wires run. The owners manual came with no wiring schematics.

[allcool]

versicom wrote:
Upon connecting the multimeter, I get a 20v "overload" spike and then 1 second later drops to 12.8v.

Common on many auto ranging multimeters to go to a overload reading momentarily while switching to the correct range. And it is diffidently not a spike, its the meter.
It means nothing and is normal. Has nothing to do with your dc voltage problem, if you even have one...

Explain in detail what you mean by...
"smoking whatever I plug into it"...


jmo

[time2roll]

20 volts does seem rather odd. It should be tied directly to the battery through the 12v distribution system. Seems like some other power source is bleeding into this 12v outlet. Is the 12v connector OEM or added after the fact? Where is it connected?

I would find the fuse that cuts power and check voltage there. Possibly a poor ground back feeding through some other system.

[versicom]

Upon connecting the multimeter, I get a 20v "overload" spike and then 1 second later drops to 12.8v. The batteries are new and all other 12v outlets work normally. It is just this one in the master bedroom that is smoking whatever I plug into it. I'm thinking I might need to rewire it direct to the batteries instead of spending too much time troubleshooting. I figured someone might have experienced this and have a quick answer but perhaps not. Cheers.

[skipnchar]

If you're only getting 12 volts from ANY 12 volt outlet then you have very low batteries (about 50% charged). Normal voltage at any 12 volt outlet should be around 12.6 volts with nothing charging the batteries at the time. Probably up around 13.5 to 14+ when batteries are being charged.

[WyoTraveler]

ScottG wrote:
Depending on your converter, it may have been in a desulfate mode for the batteries. I would go back and check it again.

When he said just a few seconds thought about static charge. Just long enough to cause problems for something plugged into the outlet.