British-Cars.org

Welcome to the DMR Site for British Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Cigar lighter socket

I have installed a cigar lighter socket to run a navigator's 'Potti', mobile phone chargers, satnav etc. All I have succeeded in doing is blowing up my charger lead. Can anyone help me before I destroy my mobile phone and satnav?
The socket is brand new, is isolated from the metal dash and has two terminals (a central terminal and an outer case terminal). I have taken power from the 'A1' terminal of the regulator, so that it is independent of the ignition.

When checked with a multimeter, the power delivery to the socket seems very spiky.

Help
Geoff
GM McGladdery

Take power from the battery supply cable on the starter switch. Why do you isolate the socket? Is the car still positive earth? That's kind of risky business. If you want to run electronic devices you would be better off converting the car to negative earth, in which case the socket shell can be grounded.
Barney Gaylord

I have a cigar lighter for just such devices sat nav, mobile phone and potti, my car is swapped to neg earth and I would echo Barney in suggesting it is by far the best course of action to take. Then simply take it from an inline fues supplied from the point noted by Barney. I have installed a new fuse box with numerous fuses supplied as described but if you want to simply use an inline then that is fine.

Alternatively take a big risk, leave the car possi earth and insulate in which case the centre connection should be earthed and the outer connection should be to the connection on the starter solenoid.

I suspect you have connected the outer connection to earth on the car?
Bob Turbo Midget England

Barney,
Thanks for your response. The socket is isolated as supplied and their seems to be no leakage to earth, the car is still positive earth.
I have assumed that the centre terminal on the socket is positive and the outer shell is negative. Are these chargers polarity dependent?
Regards
Geoff
GM McGladdery

Geoff, Yes whether your car is pos or neg earth, the pos should always go the the center of the socket and the Neg should always go to the outer shell. ALL chargers/adapters are polarity sensitive. I just installed a marine socket in another car and it was not immediately clear as to which term was which on the back of the socket. Look again at your wiring.

If your "charger lead" that blew up is the wire to the socket, I would expect that the socket you have is not isolated from the chassis as you may think. You may want to check that with an ohmeter. If this is the case, a fuse would have prevented any burnt wiring.

I the charger lead is the part plugged in to the socket, then you may have the wiring to the socket reversed. Again, a fuse would have prevented the blowup if not the damage to the charger itself.

I'm another for recommending converting the MGA to neg earth polarity. External devices could go "POOF" if plugged in and their case contacts the car's metal. Not guaranteed, but possible. Why take the risk?

Chuck
Chuck Schaefer

This thread was discussed on 27/05/2011

MG MGA index

This thread is from the archives. Join this live forum now