Reply To: Dynamo not charging battery. 1955 11BL

If the ammeter shows a discharge when such tings as the lights are on, and shows no positive charging when the engine is running without the lights on, there a couple of possiblities.

We can rule out a broken connection in the ammeter circuit because a discharge can be shown on the ammeter.

If the ammeter needle moves in the negative direction but not in the positive direction, I suppose it is possible there’s something sticking inside the ammeter – but I doubt it.

That leaves only a problem in the dynamo or the regulator – or the wiring between the two and/or from the regulator to the ammeter.

My ammeter always reads zero – I have bypassed it as I have an alternator which would probably overload it.

On a different car (my ’59 Chrysler) I found that a wire was completely missing that meant the battery could not charge. The wiring was done a bit differently but effectively it was the equivalent of the wire between the regulator and the ammeter. I had owned the car for 11 years before I realized this – I attributed the occasional flat batteries to short journeys and an old battery. I fitted a brand new big battery before driving it to Sweden – we got as far as Bremen (about 500 miles) before it would not start after a fuel stop. When the ADAC man got us going it was dark and I could see the headlights did not get brighter when I revved the engine. They just go dimmer as we drove along. A bit of buzzing out the circuit showed no connection – because there was no wire!

I have no idea if that helps

Chris