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Hi -

So my mini is overcharging the battery quite a bit. It is fine at idle (13V) but any significant throttle input brings it up to 14.5 and beyond. I replaced the Voltage Regulator with a brand new one...same results. Generator is a brand new one from Mini Spares. The car has a new wiring loom.

Any suggestions on where to look next? We measured the volts at the battery terminal, so its not a faulty gauge.



[If it might be associated in any way, my temp gauge is also reading off the charts after barely any running, but the actual motor temps are fine, which led me to believe maybe it was a faulty voltage stabiliser...but the fuel gauge reads fine.] Ack!

Thanks!
Warwick

Warwick, it sounds like the voltage regulator isn't correctly adjusted. Depending on the year of your car the fuel gauge has a separate regulator built into the back of the speedo, the temperature gauge (assuming its a factory fitted Smiths one) should also be running off the instrument regulator, but it may not be, especially if its aftermarket.

What is your wiper speed like? If its over charging they should be working really well!

I'd be looking at the regulator adjustment first.

Tim

The actual setting for charging at 1500 rpm & above with a dynamo & RB106 regulator is around 16 volts without any electical equipment switched on! I always used to check them at 1500 RPM with headlamps on main beam, at which time the volts should be around 14. This is adjustable by means of a screw located at the back of the left hand coil, looking at the regulator from the front where the connectors are. Clockwise to increase volts, anti-clock to reduce. On my rally Cooper S, I always used to tweak the voltage up a bit at the start of an event as I was running the headlamps plus 2 or 4 Oscars. Worked well, but I had to change dynamo brushes quite often.
I suspect that your temp gauge problem is nothing to do with your charging, it may be a mis-matched sender unit, or the voltage stabiliser has been by passed in the case of the temp gauge. If the stabiliser was faulty, your fuel gauge would also go high.
Just found this link which might help: http://www.wolseleycarclubnz.co.nz/bettery.html

It may be an obvious question (and the only thing I know about electrics is that it runs on smoke: when the smoke leaks out, it stops...), but did you polarise the new dynamo when you fitted it?
-I don't think it would cause over-voltage, but it should be polarised anyway.

I agree with 'Lord Croker', and it should be kicking out around 14V.
-If the battery gets warm, and the acid is bubbling, that's a good sign it's over-charging

Sounds like a faulty diode, I think (from memory) a shorted one will do that.

However, what is the amp rating of the alternator? I've found that the 70 amp ones do actually have a higher output voltage.