Lotus Elan

Polarity change plus cigar lighter

PostPost by: Bigbaldybloke » Thu Mar 29, 2018 2:25 pm

I changed the polarity many years ago when i fitted an alternator. I'm just fitting a new dash and it struck me that in years gone by it didn't matter about the polarity of the connections on the cigar lighter as all it did was heat up an element.
Nowadays we plug all sorts of electronic gizmo's into the cigar lighter and use it as just a power outlet.
So,what way round should the polarity be so I don't blow up my sat nav, mobile phone and whatever else i plug in.
I'm guessing the body should be negative and centre pin positive, but can anyone confirm this and have everyone else swapped their cigar lighter connections when changing polarity?
I know I changed the radio connections, the electronic ignition and the tachometer but its so long ago I can't remember if I changed anything else.
Change is inevitable, except from a vending machine!
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PostPost by: JonB » Thu Mar 29, 2018 3:09 pm

Centre pin is +ve. If in doubt, check with a meter.
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PostPost by: RichC » Thu Mar 29, 2018 4:49 pm

:shock:
i had similar dilemma when I KEPT to +ve earth but nonetheless wanted to charge phone etc . in the end i opted for the rather more precarious situation where the carcass of the cigar lighter is live and the earth is in the pin...
( i insulated it well with electrical tape )
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PostPost by: ericbushby » Thu Mar 29, 2018 6:02 pm

According to the circuit diagram, S1,S2and S3 models were wired with the centre contact negative and the outer positive, connected with a black wire to the earth bobbin.
Fortunately for us when you change to negative earth, this means that the polarity should now be correct for modern accessories. So there is no need to change anything, but check it first.
Hope this helps
Eric in Burnley
1967 S3SE DHC
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