Voltage too high

[frank]

Hello, I have just had dynamo refurbished, new battery and new old stock control box fitted to my 1963 vitesse and also added a Smith's volt meter. On low revs it's fine but at normal driving speeds it's showing around 15 volts going into the red. Any ideas what I can do? Can you adjust the voltage on the control box? Any help would be great.

[JohnD]

Have you checked the volts with a better voltmeter?

The volts from a dynamo depend on the revs, and can go much higher than 15V, which is one reason why you need the control box, which just stops and starts charging the battery from that, to average it and to set the charging volts to what the battery needs, which can be 14.5-15.5V.

 

And, a "new old stock" box will definitely need cleaning and adjustment.    Moss have a series of short videos about the role of the control box and how to adjust it. 

 

 

See: 

 

Good luck!

John

[frank]

Thanks I have checked the points and cleaned them refitted them . Same problem 15v at 2500rpm. The points on the voltage regulator part of the control box open when the engine is running and stay open. Only close when engine is turned off. I thought when points open no volts generated? Have refitted old control box and no difference. I'm a bit lost on this one. During all this work it's started missing on one cylinder. Not a good day in the garage!

[Pete Lewis]

I spent a long time with a local RB340 box checking all the point gaps and currents and voltages , all seem to workout in the garage

but a quick nip down the road blew all the headlamps when put on to add more load

 

so be careful  these can be mended to destruction quite easily and not for the want of trying

 

the video is great ....have faith... make very small changes and double check the results 

 

Pete