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[Healeys] BN7 over charging

Subject: [Healeys] BN7 over charging
From: bspidell at comcast.net (Bob Spidell)
Date: Mon, 23 May 2011 19:01:22 +0000 (UTC)
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 

-------------------------------- 
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 

-------------------------------- 
Bob Spidell - San Jose, CA 

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