MG Car Repair: MGA, 6 volt batteries, starter solenoid

Question
how do the two six volt batteries in a MGA hook together?  i have one possitive  one negative   and a cross lead

Answer
Hi Duncan,
I can tell you how it was originally, but you need to be careful because many "MGAs" Had their polarity reversed for radios or other reasons.

The original A had one battery (+) cable connected to the body ground. The (-) cable was connected to the (+) post of the second battery and the (-) post of the second battery was the "Hot Cable" that ran up to the starter solenoid as the power cable.

Here is the danger, IF some one has changed the polarity and you connect it up like it was originally you can damage several items and maybe burn up the harness and maybe the car along with it IF YOU TRY TO START THE CAR.

Here is a way to be somewhat safe.
1. look at the markings on the coil. "CB" should have a white w/black tracer wire that goes directly to the distributor. If the coil has been replaced with a newer coil it will be the (+) post on the coil that goes to the dist.

2. Remove the fan belt. Remove the two wires from the generator. Take a small piece of wire and connect the two posts on the generator together. With the batteries connected up as I listed above take a heavy jumper wire (12 ga.) and connect it to the starter solenoid post that received the (-) cable from the battery. Take the other end (Hot) and touch it to the little jumper you just put on the generator. The generator should start running like a slow electric motor BUT! IT MUST BE ROTATING IN THE DIRECTION THAT THE ENGINE RUNS.

These things prove that the car was as it was designed and negative as hot and positive as ground and the two 6 volt batteries are connected in series to make 12 volts.

If it is not as above you need to read my tech tip on polarity of MGs

http://mg-tri-jag.net/tech1.htm

Howard