[Healeys] BN7 over charging

[Bob Spidell]

Once again my ignorance of the 'mid-year' Healeys makes its existence known (I think my BJ8 has a three-coil VR but, actually, it's been a while since I opened it up). 

13.5V at the battery seems a bit low, which makes sense given the large current draw. My VR knowledge isn't immense; but I did study them some when my Dad's fire engine's single coil VR wasn't working properly. That engine has some circuitry in the generator to limit current output. 

My guess is the generator has a problem. There may be some diagnostic tests in the manual, or online somewhere (maybe disconnecting the 'F' lead momentarily, but research this first lest you let the smoke out). There should be something to limit current; holding a constant voltage won't limit the generator output if there's excessive current draw. 

Is your ammeter wired in series with the generator and the battery? It's conceivable the battery has an internal short. 

Bob 

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Bob Spidell - San Jose, CA 



Than ks a lot for the reply, Bob. My regulator is the two coil type and I replaced it with another and the amperage was still reading near 30. I replaced the ammeter with another I had and that still read high. There are about 13 1/2 volts at the battery at 1500 RPM. Just over 12 volts at the battery with the engine off. 

Ned 







Ned, 

How do you know the VR is working properly? AFAIK, an A-H regulator controls both voltage and current. That's why there's three coil/points sets: one controls charging voltage, one limits output current and the third controls the battery cutoff; i.e. the light on the tach. You shouldn't see more than about 13.8V on the system when the dynamo/engine is running at 1K RPM or more. 

Sure sounds like the current-limiting function is not working in your VR. Be careful--if you're overcharging the battery you'll get hydrogen outgassing (30A is not healthy for your wiring, either). 

Bob 

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Bob Spidell - San Jose, CA