Car Cigarette Port vs ACC Power Port


last year i purchased a satellite radio and i had recently purchased a garmin nuvi 1350T. my truck has a power port and cig lighter port. i plugged the garmin in the cig lighter and sat radio in the power port. one day i swapped them and poof it blew the fuse in the box going to the lighter. i knew it was not pulling that much amperage. after blowing 2 fuses. i took a good look at both ports. the cig lighter port has a somewhat "U" shaped bracket in the bottom that is connected to the batter + positive side. when you look at all acc device plugs you see 2 spring loaded clips that make contact as soon as plugged in with the - negative side of the battery , if the plug is rotated just right as you push the plug in it can contact the + positive U bracket and it is also grounded so it shorts and pops the fuse. the reason the garmin never shorted is because i turned it so the led light was on top ...maybe this will help folks look first. hope this hasn't already been covered ...i purchased a box that has 2 power ports and cig socket and hard wired them to fuse box but it came with plug if you rather use it...stan

Socket Info

There are actually two 12 volt plug and socket sizes. What I've run across on ANY appliance with these plugs is this, depending on the make of the vehicle your driving, mobile home, rv, boat, etc. You may find that the socket is the larger size and your plug the smaller. Depends on WHERE the manufacturer got his sockets from. In that case you can imagaine the lose fit, that would require constant jiggling to make contact, etc. Sometimes you'll have one size of socket up front in the drivers area, but another in the rear area of the vehicle that are labeled accesory sockets. Why they do this? I have no clue other than cost.

12-volt cigar lighter receptacle and plug, size A:

Receptacle inside diameter: 20.93 - 21.01 mm (median 20.97 mm)
Plug body diameter: 20.73 - 20.88 mm (median 20.805 mm)
Most often used in American automobiles.

12-volt cigar lighter receptacle and plug, size B:

Receptacle inside diameter: 21.41 - 21.51 mm (median 21.455 mm)
Plug body diameter: 21.13 - 21.33 mm (median 21.18 mm)
Most often used in European automobiles, and sometimes as a second socket in American automobiles expressly for DC power connections.

1996 Dodge RAM

Both ports are identical in size. The new Scion switched port is identical also...I bought two cheap 120V to 12v converters at R/S and they are a different size than the truck, but work OK. It's just that the GPS has to be plugged into them just right.

1490LMT 1450LMT 295w

Vibration problems--

One of the big problems with these kinds of connectors is susceptibility to vibration, such as from rough roads. Things tend to wiggle loose, and go intermittent.

If you're lucky, this just means your device cycles on and off, or complains about losing power.

But if you have something that draws an appreciable amount of current (over an amp, say) then you're going to have arcing as the contacts bounce around, which will result in damaged contact surfaces at least.

My conclusion and recommendation -- good for temporary use, but if it's going to be a permanent addition to your car, wire it in permanently, safely.

To do this and still be able to remove things, the ham radio community uses Anderson Power Pole connectors. they're easy to use and provide a safe, mechanically secure connection over a reasonable number of mating cycles.

Nuvi 2460, 680, DATUM Tymserve 2100, Trimble Thunderbolt, Ham radio, Macintosh, Linux, Windows

I have both a cigarette

I have both a cigarette lighter socket and an accessory socket on my ford pick-up and have used both with my Garman GPS. I have not yet blown a fuse but have found that I have to twist the plug back-and-forth to get a connection.
It seams that different manufacturers design these plugs/sockets without following any standard format.

Tight lines