Recently the voltmeter on my '82 R100RS has been fluctuating from 10v to the top of its range, 16v. It is worse for the first few miles after which it settle down to fluctuating a little less wildly at 12 to 14v. What could it be?
Charging voltage wildly fluctuating
- Thread starter John Roberts
- Start date
A change in voltage?
Oy vey, I pay twelve pounds- that's TWELVE pounds- every year, and this is what I get???A change in voltage?
AberdeenAngus
Registered user
Check the voltmeter. It might be fricked.
If the voltmeter is ok - Your regulator is fricked.
Change it sharpish or it'll cook the battery - at the least.
If the voltmeter is ok - Your regulator is fricked.
Change it sharpish or it'll cook the battery - at the least.
Regulator, then. Is this how they usually go, fluctuating wildly?
AberdeenAngus
Registered user
Could be. If your voltage varies with revs then the regulators fried.
It could, of course just be dodgy wiring if its leaping around like a mad thing.
It could, of course just be dodgy wiring if its leaping around like a mad thing.
No, you could say the voltmeter needle's vibrating (at constant engine speed) it's varying that fast. I'm just back from a couple of weeks away and the bike won't start so it looks like the battery's stuffed as you suggested it would be in your earlier post. Bugger.
Last edited:
Shep
Shep of the Dessert
It could be that the voltmeter is nacked and the battery giving up was just a co-incidence.
No, you could say the voltmeter needle's vibrating (at constant engine speed) it's varying that fast. I'm just back from a couple of weeks away and the bike won't start so it looks like the battery's stuffed as you suggested it would be in your earlier post. Bugger.
Sure this will work with an Airhead...If you want to rest a voltage regulator then you test the charge with the engine running across the battery poles... The voltmeter will probably read late 12v's up at tickover and should max out at approx 14v or slightly above when you increase revs significantly. A faulty regulator usually overcharges as it shorts and doesn't regulate and with this overcharge, cooks the battery... Hence why you usually change both...
As I have had several Honda's I was used to the test...
as even the stongest of mechanics can have some crap electrics.... The problem with charge lights/dials is they can show increased resistance or fluctuate and so you are often checking the instrument rather than the regulator...Older K bikes can have charge lights that glow as you increase the revs as the resistance in the light connections builds with corrosion....
I have no experience on airheads but i repair a lot of car/truck alternators.My guess would be BMW use a bosch charging system,if this is the case the symptoms mentioned would indicate a regulator fault which is common on bosch car and truck charging systems.If it is bosch either its a seperate regulator or it will be fairly easy to screw one into the alternator.Not sure if you can do it on the bike or wether it would need the alternator removing..
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