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Author Topic: Source for heavy-duty male 12v plug?  (Read 18827 times)
K1CJS
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« Reply #15 on: February 27, 2011, 08:03:43 PM »

I'm late... But i dont think the plug itself matters. its the gauge of the wire behind it. Replace the wire with something better along its path to the battery.

Oh, but the plug--and the socket--DO matter.  If you use a cigarette lighter plug for a high current application, (and by high current, I mean 7 to 10 amps, like a battery operated compressor) you're going to find that both the plug and the socket will get hot in very little time.  It makes no difference that a cigarette lighter socket is designed to get hot--the plug that is used to connect those items can melt--and you'll have an incident that would result in a picture like the one on K0BGs website.

If you would take the time to look at the wiring behind some of the older cars cigarette lighter, you will find that the insulation on the wires has been heated so many times that it becomes brittle, and would break off the wire with just about any movement. 

Those sockets just are not designed to handle high current applications.  Period.
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W8JX
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« Reply #16 on: February 28, 2011, 05:32:40 AM »


FWIW, I don't care what power ratings an auto manufacturer puts in their owner's manual, there no "power port" in the typical vehicle that can handle anything approaching a 20A load.

I do not agree as many are rated to 25 or even 30 amps. The "problem" is in the plug/connector as many do not connect firmly enough on insertion that resistance can develop and under extended heavy load can result in socket/plug heating and failure.
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K0BG
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« Reply #17 on: February 28, 2011, 07:04:05 AM »

Okay John. Which vehicle (make and model) has a cigarette lighter (accessory) socket rated at 25 or 30 amps?

Oh! And what size wire is it wired with?

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W3LK
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« Reply #18 on: February 28, 2011, 01:10:30 PM »


FWIW, I don't care what power ratings an auto manufacturer puts in their owner's manual, there no "power port" in the typical vehicle that can handle anything approaching a 20A load.

I do not agree as many are rated to 25 or even 30 amps. The "problem" is in the plug/connector as many do not connect firmly enough on insertion that resistance can develop and under extended heavy load can result in socket/plug heating and failure.

My '03 Windstar has three 12V outlets - the normal cigarette socket, a "power port" on the side of the lower dash console and another on the rear, inside quarter panel. According to the owner's manual, the "power handling capacity" is dependent upon the size of the fuze one installs in the circuit - 20A = 240W, 15A = 180W, 10A = 120W. Please note that both power points are wired with 14g wire - run to the fuse panel. No way you are going to have a 12V/20A draw on those circuits without the insulation melting and a resulting fire. Even if you don't have a fire, the resulting voltage drop will be significant.
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W8JX
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« Reply #19 on: March 01, 2011, 07:06:21 AM »

Okay John. Which vehicle (make and model) has a cigarette lighter (accessory) socket rated at 25 or 30 amps?

Oh! And what size wire is it wired with?



Well for starters my old 2000 chevy "classic" body style P/U it has two circuits for aux power and one is fused to 20 and other to 25 and I have pulled well over 20 out of them with no problems. Only problem I have seen is as I stated the plug itself. Wife Jeep Cherokee has two circuits two and each will easily handle 20 amps as well providing proper plug is used. Most problem can be traced to poor plugs causing sockets to heat and fail.
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K0BG
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« Reply #20 on: March 01, 2011, 10:09:08 AM »

The real issue is voltage drop. Depending on the size of the PU truck, most F150/F250 sized ones, have trailer hitch B+ connections for charging house batteries. Most are wired with #10, and couple are wired with #8 (F350). even then, at rated load the drop is about 1 volt. Oh, that's only 12 watts, what's that to worry? Change the wire size to #14, and at 20 amps, the voltage drop is nearly 2 volts! Oh heck, that's only 24 watts! I suppose that's okay, but certainly not for continuous duty. If you wish to risk a wiring fire, have at it. But I for one, wouldn't take the chance on a bet!
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K1CJS
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« Reply #21 on: March 03, 2011, 04:47:29 AM »

Well for starters my old 2000 chevy "classic" body style P/U it has two circuits for aux power and one is fused to 20 and other to 25 and I have pulled well over 20 out of them with no problems. Only problem I have seen is as I stated the plug itself. Wife Jeep Cherokee has two circuits two and each will easily handle 20 amps as well providing proper plug is used. Most problem can be traced to poor plugs causing sockets to heat and fail.

Define "no problem" if you would.  Did you actually feel the wiring and see if it got hot?  Did you check the wiring at all?  Mind you, I'm not saying that you're pulling examples out of a hat, but if you did check them, you probably wouldn't try to pull that much current through the power socket again. 

The only REAL experience vehicle maunfacturers have with the 'power sockets' comes from their experiences with cigarette lighters, and as I mentioned before, look at the rear of a cigarette lighter socket on an older car.  One gets you ten that you'll find wiring that is brittle from being overheated--ready to crumble if moved.  There is another reason that most car makers put a tie point to secure that wire a couple of inches from the socket--not only for strain relief.  They either suspected--or knew--that the wiring was marginal for that application--especially on sockets built into sliding cigarette ashtrays--and they wanted to stop ANY movement of that wire because of crumbling of the insulation and the resulting fire danger.

And, please, don't start with the old saw that they wouldn't have done such a thing.  They had engineers and accountants looking for any way they could save money on the building of a car--and they frequently cut parts quality and or capacity down to where the part would just do the job it was made for.  Then remember that cigarette lighters were made for use maybe--MAYBE--thirty seconds at a time, not for minutes at a time that a high powered radio would draw.

Lastly, there is a reason that both Ford and Plymouth cars that were popular with police departments in years past were made SPECIFICALLY with a police wiring package.  Those packages included a higher power alternator, BUT ALSO brought at least two or more high current power sources into the passenger compartment and the trunks of those cars--ten, eight, OR EVEN SIX gauge cables to a tap off point under the dash and in the rear compartment.  And that was done because of the power requirements of radio systems and lighting packages.

With that in mind, tell us again that you believe what vehicle manufacturers say the rating of power sockets in cars of today are.  Tell us again that those outlets can take the so called 'high current' use that a ham rig would have to have without damaging the rig from voltage drop or chancing setting fire to a wiring harness.   

No offence intended--but if you still insist that those ratings are accurate and that those outlets and their associated wiring can take the load and supply the power needed, then you are either gullible, a total fool--or both.   
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N1DVJ
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« Reply #22 on: March 10, 2011, 05:40:33 AM »

The problem is that what an auto manufacturer defines as a power port is not what we would define as a power port.  Sure, they put a 20A socket in the rear of my old Caravan, but it's not clean power.  It's designed to run compressors or other devices that don't care if the power is dirty or even drops.  It's also not generally expected to run continuously, although we shouldn't be transmitting continuously either...

I'm late... But i don't think the plug itself matters. its the gauge of the wire behind it. Replace the wire with something better along its path to the battery.

The plug DOES matter.  I make up a quick 'grab and go' cable for all my radios.  It's nice to make a proper installation with PP connectors, but there are times that's not practical.  WAY too many people get a bug up there exit portal about something not being the right way to do it, but sometimes you just do what works.

With that in mind, I have a number of 'lighter plug' cables for my radios.  Sure, I don't want to run 50W on TX, so I turn down to 10W on my Alinco.  I had a reset where I had to reprogram and forgot to turn the power down.  Melted the plug I used.  It was a 'high current' plug with built in fuse and 16ga wire.  Melted almost to a puddle and blew the vehicles fuse.  I took it apart to find out why. 

The fuse was in a metal cap that screwed on.  There was a spring behind the fuse.  In operation, the metal cap had a 'wiper' to make contact across the spring, but that wasn't always robust.  As a result, the full current went through the SPRING, which turned into a heating element (it looked like a burnt out filament when I broke it apart) which started the path to destruction.  Since then I have found what looks like 'bakelite' connectors that unscrew.  The center contact doesn't have a fuse.  The wire solders DIRECT to the contact pin at the end of the connector.  The ground lead is a single wire of 14ga spring steel bent in a loop to offer contact at both sides.  I've used those with no problems, even when I mistakenly left my Alinco in high power for a day...

The plug DOES matter!
« Last Edit: March 10, 2011, 05:45:48 AM by N1DVJ » Logged
K1CJS
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« Reply #23 on: March 15, 2011, 06:10:40 AM »

>> WAY too many people get a bug up there exit portal about something not being the right way to do it, but sometimes you just do what works.<<

And on the other hand, way too many people think that what they're using is fine and won't hurt the vehicle--until either a fire starts or the area around the cigarette lighter/power port melts.  No matter what is used for the plug, the weak point is not the plug or the wires that connect to it--IT IS THE SOCKET AND THE WIRING THAT CONNECTS TO THAT!

Please understand that I'm just trying to get a point across.  You can have an old style bakelite lighter plug and good, heavy wiring to the radio from that plug--but with modern vehicles, the weak point is in the vehicle wiring itself.  Newer cars, especially foreign cars sometimes use twenty gauge--or smaller--wiring in harnesses under the dash!  If the manufacturers will use that because current concerns aren't that great, what are they using in those 'power ports'?  Most I've seen are wired with eighteen gauge wire--MAYBE sixteen gauge on heavy duty models.

What you may use may work--but at what final, possible cost?  

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K0BG
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« Reply #24 on: March 15, 2011, 06:49:52 AM »

Look at this photo: http://www.k0bg.com/images/wiring/wirefire.jpg

Look closely what the arrow is pointing to. That is a cigarette (accessory) port plug, or what's left of it.
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