SWMBO's car fridge melts its connector...

[Owain]

"Lobster" wrote | I checked the rating of the fridge and the max rated output of the | car socket, as provided by the mfr, and it was fine (I forget what | the figures were; something like 50W and 100W respectively?).

40W is slightly over 4A current at 12V, so ample current to cause a poor connection to heat up.

| [1] Why is it that the car cigarette lighter has by default defined the | international standard for low voltage appliances intended to be powered | from a car battery?

*because*

| these appalling sockets are found on every car

Owain

[Huw]

'electrical

Yep. My '98 Toyota has two in the dash, one in the rear seating area and two in the boot. My wifes X5 BMW has only one in the front, which is a nuisance, and one in the second row and one only in the boot.

Huw

[Huw]

There is a standard for three pin plugs for automotive accessories. These have unequal sized pins with two twelve volt, one being continuous live and one linked to the accessory position of the ignition key. They are also rated for a different current and fuse. The third pin is earth. The bottom of the socket is flattened while the rest is roughly round.

Huw

[Huw]

I've never had a problem, even in industrial use controlling electric rams and motors in almost continuous use. I use two sockets simultaneously, one for an electric fluid pump and the other for the afformentioned use but also various solenoids which actuate hydraulic divertor valves, all controlled by two joysticks and a bank of rockers. And no, there is no relay involved and all the current goes through one cigar type socket [for the main controls]and one three pin type which happens to power the fluid system.

Huw

[Just zis Guy, you know?]

The distribution board (only) has circuit breakers - which amounts to the same thing: overcurrent protection.

Guy

[Just zis Guy, you know?]

And British electrical circuits always seem to have about twice of many of the things.

[ G Chapman, B.Eng (hons), MIEE - I know what fuses are for :-) ]

Guy

[Lobster]

Good thought; in fact I've already done the job actually using a 30A terminal connector from the bottom of a drawer: I stripped the insulation away from an inch of the wires leading to the ciggy lighter and bent them double, without chopping them, and wired these into one side of the connector, with the fridge flex wired in the other side. Thus I can 'unwire' the fridge lead in future if need be, without no deleterious effect on the car or it's wiring. And what's more, SWMBO is smiling again.

And yes, I'll remember not to use the ciggy lighter at the same time as the fridge!

David

[Lobster]

Hmm - I just destroyed the molten plug while removing it from the flex, and embedded in the middle, unbeknown to me hitherto, was a fuse! I had to check it, didn't I - yes, it was still intact. Don't know the rating (although it was as supplied by the fridge m'fr) and I ain't spending an hour scraping burned on plastic off the ends to find out!

David

[Fran]

What? When?? Quick, STOP HIM! You cannot let that man escape! Trap him, tie him up *thoroughly* and send him over to me please; I've been looking for a leccytrician for nearly a year!

[Chris 159]

shame you live so far away cos im quite handy with the old sparky things. i could have sorted you out (oo-err missus) for a coffee or two ;-)

[Fran]

Hang on - are you saying /you're/ an electrickery person? And all this time you've kept quiet, knowing full well from elsewhere that I've been looking for one??

[Just zis Guy, you know?]

I'm not an electrician, I'm an electrical engineer by training and a geek by trade. But which thread in Ye Shedde?

Guy

[Fran]

I doubt you'd have done the job for a coffee or two dozen, let alone two. It's a complete house re-wire and the house isn't exactly small. But I do have bags of floor space for anyone enterprising enough to have a stab at the job, which is worth around two to three thousand squids to the right victi^^^^^ applicant.

[Fran]

Just about any where I've mentioned the rewiring of the house.

[Chris 159]

complete re-wires are the best kind of sparky jobs IMO i like a job that i can really get stuck into. like i said - shame you live so far away :-(

[raden]

In message , [e-mail] writes

Which is why we're talking about cars ... or did you miss that bit ?

[raden]

In message , "Just zis Guy, you know?" writes

[ G Drage, B.Sc (Hons), MIEEE]

[Scott M]

Well, it's not surprising the fuse is ok - it's there to prevent too much current being drawn (mostly in the case of a short circuit.) Your fridge operated normally and within spec of the fuse, but overloaded the connector.

[Questions]

Seems to me there are usually hierarchies with a fuse on the supply side to protect the power company network, a breaker on the service side, smaller rated breakers on individual circuits to control current loading for various floors or particular things like lighting, and fuses at the socket delivery so that a short in the plug (as it were) blows the fuse on the socket but doesn't shut off power to the entire office block.

Either way, this is all specified in some sort of regulatory stuff so even if it was over specified, it's compulsory and the bloke was either quite wrong about what was required, or just following orders.

For all I know, he or she didn't fancy doing the job, had a bunch of obsolete individually fused output stuff to flog some unsuspecting punter, or whatever, and invented some spurious regulations to convince your building bods to buy his kit / do it another way.

[Richard Hankins]

I have done exactly the same thing with a car fridge. They take about 4 amps - and the plug design is simply not man enough for the job. Forget fuses - the normal current drain is quite enough to cause the problem - and that won't blow the fuse.

Its all the fault of someone long ago who thought it would be a good idea to take some power off the car lighter socket......and years later every man and his complete zoo have jumped on tbe bandwagon, so we now have the absurd situation where currents up to some 10 - 12 amps can be drawn into certain appliances.

What appears to happen is that one of the metal contacts in the plug fails to make a proper contact - and it then gets hot. Given its in an enclosed space, the temperature rise is rather rapid and uncontrolled - and it continues until something breaks - usually the plastic, which melts.

I don't have a solution other than to make sure the contact surfaces are clean, and chose a plug with plenty of contact pressure - and then push it in very firmly. If that fails - then try installing a proper 12V power take off with a sensible connector in circuit - something actually designed to carry 5 amps or more.

Richard

Scott M wrote: