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

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.

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.

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.

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.

What model converter? What is the actual voltage?
Up to 14.8 is probably normal.

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

Aren't all the 12v outlets connected to the same bank of batteries? Of coarse voltage is higher when charging but When you say higher for a few seconds, how much higher? Could you be getting a static charge for some reason when you plug something into that outlet?

Thought about this. Maybe a static charge could be building on the run to the bedroom area. In the past I have taken 2 wires, hot and ground, put them in an electric drill and twist them up so you have a twisted pair. Sometimes that will prevent things from being picked up on the line. Just a thought. Don't know if that is your problem or not.