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MG MGB Technical - Basic Electrical Question

OK, I've taken my cars completely to pieces and put them back together in the right order, but I've never known the answer to this. Is it OK to trickle charge the batteries by clipping the charger to the starter terminal under the bonnet and to a good ground? Do you have to disconnect the alternator?

Mike Howlett


Why don'tyou fit a cigar lighter plug to the charger wire, that way you can charge any car without having the hassle of finding somewhere to fit the croc clips ?
M Barnfather

Mike - you can connect the charger anywhere there is 12v and a ground when the ignition is off. The brown terminal on the fusebox is easier to get at than the solenoid, if the solenoid is down on the starter as on most MGBs. But even if the solenoid is on the inner wing and the battery cable easy to get at the purple on the fusebox is better as this is fused and guards against damage (to car) if the croc-clip shorts to ground.

And as MB says the easiest way to do this is with a cigar lighter plug on the end of your charger leads. I thoroughly confused a couple of work mates when I first did this years ago, they were trying to understand how I could power a charger from the car I was trying to charge! It is worth wiring a cigar lighter to the purple (fused always live) circuit and ground if your car doesn't already have one, even if it is mounted out of sight under the dash.

Certainly with trickle charging you don't have to disconnect the alternator, although with high-voltage rapid boost charging (in excess of 15v) it may well be advisable.
Paul Hunt 2

Mike - I second Paul's suggestion to wire in a cigar lighter plug somewhere in a convenient plase in the car (I installed one in the rear bulkehad behind the passenger's seat). The one I got (from a boating supply house) was called an auxillary power connector and came with a cover for when it is not in use. In addition to being able to quickly and easily attach a trickle charger (or one of the newer battery conditioners), you will have a ready port for plugging inyour cell phone, lap top or even a small inverter to have low current AC available if needed (we use this feature to use the map program on our lap top when traveling). Cheers - Dave
David DuBois

Thanks all. My '71 doesn't have a cigarette lighter, so I'll go for the fuse box option.

Mike Howlett

go to a bike shop and buy an oxford oximiser charger then connect the lead to the battery then put the connector block poking out under the battery cover this way you can just plug it in at any time
the connector is only the size of a ciggy butt very small and cant be seen under the carpet
its also fused
thats how i did it on my gt as the alarm would run batterys down
they are only 25pounds and you get a crocodile clip part as well
its a charger conditioner so wont over charge the batterys
Ste Brown

This thread was discussed on 05/03/2006

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