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Hot 12volt power point

This forum is dedicated to helping people with questions about installing radio equipment in vehicles. This can include antenna installs, electrical wiring questions/problems, and mounting systems. Pictures of installs are welcome.

Note: Discussions regarding lighting, sirens, and other equipment now has its own forum in the 'off-topic' section below.

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Andy Corbin
Posts: 126
Joined: Tue Apr 19, 2005 3:46 pm

Hot 12volt power point

Postby Andy Corbin » Tue Aug 16, 2016 11:02 am

After working at the PD for 33 years and retiring, I got a call a few months ago to see if I was interested in some part time work working on radios, radars, lights, sirens, etc. I took the job. I know I won't get rich doing it, but its something to do and I get a little extra folding money.

I went to work yesterday on a complaint of a 12volt power cord not charging the in-car computer (Dell). I checked out the power cord and it tested OK. When I was talking with the officer who drives it, he told me the computer is showing 100% battery but when its unhooked from the power source it drops back to about 3% in a matter of minutes. The batter is only a few weeks old. What concerned me though was the officer told me whenever he plugs anything into that 12 volt port (cigarette light plug), the plug gets hot...so hot he cannot touch it. Even low current devices such as a GPS or cell phone charger, the plug gets hot. I went in today and removed the old 12 volt socket and installed a new one, running heavier gauge wire back to an aftermarket fuse block. I don't know what the current draw is on the computer, maybe 2-3 amps, but certainly a cellphone charger or GPS is not going to draw enough to make the plug that hot. I took a picture of the plug and wiring and you can see the heat discoloration on the red lead. I will see how this works out for him.[/img http://s918.photobucket.com/user/1hogri ... sort=3&o=0]

RFguy
Posts: 1294
Joined: Wed Dec 21, 2005 6:17 am

Re: Hot 12volt power point

Postby RFguy » Tue Aug 16, 2016 12:27 pm

Typical high resistance connection. Yes a cellphone/GPS can draw enough to make that connection hot.

VE3HKB
New User
Posts: 53
Joined: Fri Aug 07, 2009 11:11 am

Re: Hot 12volt power point

Postby VE3HKB » Tue Aug 16, 2016 2:04 pm

Or arcing at a bad (internal) crimp. Is the outlet in the dash (plastic) or in a console (Havis, etc.)?

User avatar
Andy Corbin
Posts: 126
Joined: Tue Apr 19, 2005 3:46 pm

Re: Hot 12volt power point

Postby Andy Corbin » Thu Aug 18, 2016 4:29 am

The outlet is in a Jotto Desk console. What concerns me, this is the second car this has occurred in. I have suggested inspecting every car in the fleet with this power port configuration. The powers that be agree with me. Whether they go through with it.......?

Also, inspection of the connecting pins, and points where power is transferred show no arcing, carbon buildup, corrosion, oxidation or anything that would suggest something that would cause internal resistance in the plug. Nothing but shiny metal.

User avatar
Bill_G
Posts: 3055
Joined: Thu Sep 17, 2009 5:00 am

Re: Hot 12volt power point

Postby Bill_G » Thu Aug 18, 2016 5:23 am

It's just crappy metal causing poor contact. When any significant current is pulled, it heats up. And the more it cooks, the worse it gets.

fineshot1
Posts: 910
Joined: Wed Oct 12, 2005 5:13 am

Re: Hot 12volt power point

Postby fineshot1 » Sat Aug 20, 2016 5:50 am

Andy Corbin wrote:I went to work yesterday on a complaint of a 12volt power cord not charging the in-car computer (Dell). I checked out the power cord and it tested OK. When I was talking with the officer who drives it, he told me the computer is showing 100% battery but when its unhooked from the power source it drops back to about 3% in a matter of minutes. The batter is only a few weeks old. What concerned me though was the officer told me whenever he plugs anything into that 12 volt port (cigarette light plug), the plug gets hot...so hot he cannot touch it. Even low current devices such as a GPS or cell phone charger, the plug gets hot. I went in today and removed the old 12 volt socket and installed a new one, running heavier gauge wire back to an aftermarket fuse block. I don't know what the current draw is on the computer, maybe 2-3 amps, but certainly a cellphone charger or GPS is not going to draw enough to make the plug that hot. I took a picture of the plug and wiring and you can see the heat discoloration on the red lead. I will see how this works out for him.[/img http://s918.photobucket.com/user/1hogri ... sort=3&o=0]


I have a similar but not same issue with an older laptop that recently got what i was told was a new battery.
I later found out that the battery was an old stock new battery. The battery had been sitting on the sellers
shelf for over 7 years. The fact that there are 2 loads(battery charging and laptop operating)at the same time
was too much for this battery and the battery got real hot so i recommended to the owner that he contact the
battery seller and seek either a real new battery replacement or get his $ back.
fineshot1
NJ USA

RFguy
Posts: 1294
Joined: Wed Dec 21, 2005 6:17 am

Re: Hot 12volt power point

Postby RFguy » Sat Aug 20, 2016 8:50 am

Does it use a 1/4" QC (push on spade) terminal on the back? We learned years ago that the cheap ones (female end that crimps on the wire) do this exact thing. We switched to AMP brand and resolved the issue. The problem is in the design of how the terminal is tensioned. The way the terminal is rounded provides a strong spring tension on the male terminals. Cheaper ones are

This is a good one:
Image


The female side of this one is the crappy type. The sides are not fully rolled over to make a strong spring tension connection.
Image


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