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MG MGA - Not Charging


I have a 1960 MGA roadster that is having battery charging problems. The battery is a group 26 Interstate ( I switched from twin sixes). The connections at the battery are good and I've charged the battery. The ignition light glows very dim when the engine is running. I checked the wires on the back of the generator with a volt meter. The large yellow one runs 14.5 volts or so at high idle. The smaller wire's voltage drops off when I increase the engine speed.

I want to clean the contacts inside the regulator but am not sure what to do. I've searched the archives on the control box/regulator. Can anyone offer suggestions as to how to test?

Thanks in advance.
Dave
David Plantz

David - It sound like your generator is working properly. The 14.5 volts at idle sounds a bit high, but I am not an expert when it comes to regulators. I would suggest contacting Bob Jeffers at bobj20@adelphia.net and get his advice on the regulator. If the regulator turns out to be bad, Bob can convert your regulator to solid state in it same case so it looks just like an original regulator, only it works much better and the case will be all shiny, like new. Good luck - Dave
David DuBois


Here's an update on the A's charging problem:

After starting the engine, I can pull the ground cable off of the battery and the engine dies immediately. Wouldn't this suggest that the generator is bad?

When a voltmeter is connected between the battery ground terminal and the ground cable I get a reading of 5 volts. This is obviously too high.

Any suggestions as to how to proceed?

Many thanks,
Dave
David Plantz

Clean/replace batt connections & cables.
See "ignition light" on Spridget technical board.
FRM
FR Millmore

David - Here is a procedure for testing the generator to see if it is good.

To check the generator/dynamo - disconnect the wires from its terminals, connecting the two terminals together and to a 20v voltmeter. Start the engine - DON'T rev it!! - just slowly increase the revs watching the voltmeter. It should get to 20v by the time you get to 1000 rpm. DON'T exceed 20v. If that checks out reconnect the wires to the dynamo with the voltmeter on the D terminal (brown/yellow wire) and again start up and slowly increase the revs watching the voltmeter. The voltage should rise then stabilise at about 14.5v, if it goes higher again don't let it go over 20v. If it stabilises at 14.5v it is charging OK. If the D terminal shows only about 1v there is a disconnection in either the brown/yellow or the brown/green between dynamo and control box, or a fault inside the control box. Good luck - Dave
David DuBois

Here's a pretty good link:

http://mywebpages.comcast.net/rhodes/generator.html

I have another you can try, too.
Tom

Here's the other one, it has some fresh ideas:

http://home.vicnet.net.au/~mmccv/Tech-Reg/Regulator.html

I don't think you're supposed to run the thing with the battery disconnected. If you do that with an alternator, I think you burn up the diodes, so don't get in the habit, could get expensive.
Tom

This thread was discussed between 04/07/2006 and 05/07/2006

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This thread is from the archive. The Live MG MGA BBS is active now.