need advice troubleshooting ciggy lighter socket in Burro

[rabbit]

I have a 12VDC "socket" in the Burro. I have a small 500watt inverter thru which I wanted to power a laptop off the grid. Inverter got its "got current" green light but when turned on ready light stayed red and I got a popbampowphizzf when I plugged in the computer. I quickly unplugged; no damage to the laptop. To determine if inverter damaged or defunct, I plugged it into the accessory port (guess that's what it's called now that nobody smokes and everybody 'putes) in the rear of the 4Runner. Current present and ready lights both green when on and it lit two 100wt spiral fluorescents just fine. Tried the same in the triailer socket; ready light stayed red; bulbs flashed momentarily; AND light under the range hood got brighter. Next I checked voltage on both the truck and trailer sockets: trailer socket read 11.78 volts; both truck sockets read 12.62 volts.

Something is fouled up here. What should I do next besides the obvious answer that I need to trace white and black to their next destination? Thanks.

jack

[Ron in BC]

I've used a lot of that type of 12 volt outlet over the years, mainly in boats. I've never considered them to be really good quality and have had the same sort of problems. Sometimes the problem has been poor ground, corrosion on the connections or internally and partly broken wires just making intermittant contact. I'd start with confirming the wires to the outlet have a steady output even when "jiggled" (technical term )

Good luck

Ron

[rabbit]

Give it a look, Ron. There is some corrosion inside the socket. I'll put the multimeter on a ciggy to minijack power adapter for a radio and challenge the integrity of the terminals on the back inside the cabinet. Maybe all I need is a new socket. I sort of doubt it's THAT simple as I got a steady reading on voltage. Maybe that's meaningless? About all I know about electricity is a lot of fellers gave their names to its numerous manifestations. Ohm my, I think that's Milly Ampere over there. Watt's that joule she's wearing?

jack

[Matt in SV]

Did you check the polarity. I believe the center is supposed to be positive. That could explain the problem.

Another option is you are trying to draw more current than the outlet can provide. I don't know what kind of start up current you have but you won't 500 watts out of that socket (at 12 volts that would be 40+ amps!)

Regards,

Matt

[ThomasE]

I only use my trailer 12v socket to power a portable fan I have. I have an even smaller inverter, 80W that doesn't work either. Many possibilities, wiring from converter to socket is too small, too many connections done via scotch locks or crimps, can all contribute to voltage drop. I was considering a 400W inverter for a while, to power a laptop. I would wire directly to the battery even for the 400W inverter.

[honda03842]

Just a thought and probably not your problem but a cigarette lighter output is only capable of supporting about 100 watts.

I believe the typical cigarette lighter connection is only capable of 10-15 amps or supplyng 120 to 180 watts of 12 volts to the Inverter.

As well when drawing these higher currents, the voltage at the cigarette lighter plug may drop to a low voltage, again depending on the gauge of the wire that supports the lighter.

I personally restrict myself to 100 watt Inverters on the cigarette lighter. As well this seems to be adequate to support my computer.

Typically larger Inverters are connected directly to the battery with heavier gauge wires.

[rabbit]

I didn't make the darn inverter; I just read what's on the back which is the rated max output of 500 watts. LOL I don't believe for an instant that any laptop is drawing even a 100 watts (Google says average 65 to 70). Inverter works on a 12 volt behicle battery and supplies either laptop or a couple light bulbs so I don't think my ignorance need suggest that I think I should get 500 watts out of the lighter socket. I doubt if the inverter is the heart of the problem but what do I know? But bad ground with a 12 volt trailer system? Oh yeh, I can believe that!

jack

... and I will check the polarity with the multigadget.

[Greg H]

Yes , check the polarity because reverse polarity will quickly turn the inverter into a paperweight. Don't ask me how I know.

[rabbit]

I just spent a few minutes checking a couple of things. First the polarity. I believe if the center bottom terminal is positive, the polarity of the hookup is correct. I find it impossible to put the multimeter probes in the darn thing without a dead short but thru the minijack power adapter--red probe inside the jack, black on the outer sleeve), I don't get a minus sign and with the oppo, I get the negative sign so seems correct to me.

As for the 500watt connundrum, I plugged the inverter into the lighter socket in the 4Runner again to power the two lightbulb fixture. This time I didn't start the engine but did it with the ignition on accessory and guess what? Whatever the draw or the output of my inverter, those bulbs light up nolo problemo. Educate me. Is the starter batt in my car more "tolerant" of demanding inverters than trailer 12volt system?

jack

[Jon Vermilye]

If the wiring to the trailer socket is undersized, you might be getting enough voltage drop to cause the problem, although I find it hard to believe that the inverter without a load draws enough to cause the "ready" light to stay red. In any case, some inverters will shut down if the input voltage is too low. I'd also try to clean the corrosion from the socket - that can also cause a voltage drop.

To determine if it is the wiring or the battery you might try connecting the inverter directly to the battery (Radio Shack sells inexpensive "lighter" sockets with pigtails).

[Bob Miller]

Better Yet..... Junque the existing socket and get a new one. Most originals have the ground attached to a tab that is on the collar that holds the socket in place. This leaves a lot of cr@@@y electrical contact area to build up corrosion over the years, and it also works loose very easily. This is not to mention what the inside of the socket looks like. That the U.S. went to these as a universal 12VDC plug resulted in a real PITA. Europe uses a special 2 prong plug for 12 volt accessories.

[rabbit]

I tried one from Radio Shack. Results at the inverter identical to the existing. I'm thinking a new dedicated 12 volt line is the way to go. The black appears to lead back to the converter and service; I have no idea where the white travels to up forward. Maybe it's a tap to another white in the left side dinette locker or maybe it's a tap inside a cable bundle. I have lost interest in finding out. Why wouldn't another white lead off the buss bar solve the problem?

jack

[Bob Miller]

Testing 1-2-3
Try running a jumper from a known good ground to the outside shell of the outlet, you can use a regular battery jumper cable for that. If the problem goes away you have found the problem, a poor ground, a problem that fiberglass builds are nortrious for having.

[rabbit]

That sounds like a very good idea, Bob. Thanks. I assume the buss bar is exactly that--a known good ground? Or is it just the intersection of all the commons? I ran my FantasticFan exactly that way; is that incorrect and I have no chassis ground?

jack

[Bob Miller]

Sudden thought....
Be certain that NONE of your 120VAC ground or Neutral wires are also connected to that buss bar. The 120VAC lines should see the entire trailer like a giant extension cord and there should be no connections to the same ground that the battery is connected to. With the shore line unplugged, and all breakers ON, check for continuity between all pins in a 120 Outlet and chassis (DC) ground.
If you are talking about a Buss Bar inside the converter it MAY be connected to AC ground and you don't want to also use that for your battery. In the OLD daze, when there were just lights and fans to deal with, than might have been OK, but microprocessors do not like seeing any part of the ac signal on the dc inputs.
Bottom Line: The Battery ground/chassis ground must not be connected to any of the A/C wires....

[Bob Miller]

A Quick Thought
The 120VAC system in the trailer must be completely seperate from the DC side, this includes grounds. If the Green 120 VAC ground wire is connected to the same buss as the battery ground it can give microporcessor electronic stuff lots of problems. The battery (-) must be connected to the frame, the 120 VAC ground MUST NOT be connected to the same ground or the frame. If the Buss you are talking about is inside the converter it is usually the AC ground and must be floating apart from the frame etc.
With the shore power cord unplugged and the breakers all on, check for any continuity between the 120VAC outlet pins (all three pins) and battery ground. If there is a connection, it something that will have to be fixed. Microprocessors DO NOT like any a/c component on the DC lines and the green ground is a good place to find that. In some trailers I have even seen the neutral wire connected to the green ground. Back when all we worried about were lights and fans that was OK, no more. The A/c system should look like a giant exrension cord to the shore line.

[rabbit]

AC is all on breakers. DC fuse block and buss bar in separate cmpt. I did try jumping the socket shell terminal to the DC buss bar with an alligator clip lead. Result continues the same at inverter. Can I check for an "AC component" to DC current with multimeter?

jack

[Bob Miller]

No, a multimeter can't see the a/c leakage. But you can test for continuity between the a/c wires and the frame of the trailer with one. Those should all be open circuits. Also check between the green a/c ground wire and the DC ground buss, there should no continuity between those either. Many a trailer has had the a/c ground connected to the frame, along with the ground side of the battery, it shouldn't be that way any more.

[rabbit]

Thanks Bob, I'll do as much of that as I can understand how to do. I can see that there's a mess created by theory (changing over time) and no theory (the way your brother-in-law does it). Also thinking about cutting my education short and dropping out of school to run a chunk of #14 straight to the battery on the advice of another poster. Any harm in that? I noticed the Rat Shack lighter socket pigtail had an inline fuse; guess I should do also, huh?

jack

[Bob Miller]

If your shore cord is plugged in you will still have the same problem if it is being caused by cross tied grounds.
As mentioned, if you get a lot of voltage drop or have a low battery, the inverter will complain loud and clear.