I'm guessing the Haynes figures have been taken from an optimistic spec sheet somewhere, they look like peak-peak AC voltages + sales pitch hyperbole, the original measured figures from ASK are much more sensible - the sort of RMS figures a multimeter would return.
The Ducati service manual spec is same as quoted by the Haynes book Specifically 1500 rpm >/= 35v 3000 rpm >/= 70v 6000 rpm >/= 140v It goes on to say that values below these can be due to a partially demagnetized rotor or partial short in the coils (which should be 0.2-0.4 ohms), to me it looks to be working ok but is a little tired as you would expect on a bike with this generator and regulator. It has a marginal performance in practice and is critical to the reliability of the bike. FTR the output is 350w. Keep those connector contacts clean, tight and treated with a contact cleaner/anti corrosion compound and inspect regularly
You could have fitted it back in the coolest place on the bike while you were at it, this has been problem free for about 9 years and I am still on the same battery ( Motobatt ) that I fitted 11 years ago. Steve
Yes, you could do that, but the original place has more than sufficient cooling, the mosfet doesn’t get hot at all.
At 3000 revs All mounted and complete. Don't forget to insulate the white/red wire terminal on the bike loom near the battery bcos if the charging bulb is left in the dash this terminal will become live once the ignition is switched on.
Next job. The little voltmeter mounted in a small plastic housing I found lying around. Will wire the positive into any feed which comes on with the ignition (high beam maybe bcos that will give me the option to switch off the display if the high beam is off).
Just a quick update. The new system is running fine and the rectifier itself cool. I wired in the little voltmeter just earthing it to one of the bolts and running the positive lead to the high beam bulb. If I want to see the reading I just have to flick the high beam on so it's not on all the time to distract. It's cable tied into place and didn't require splicing into any original wiring either. The voltage readings on the voltmeter are about 2 volts less than at the battery consistently so I know what to look out for to check the charging status. The charging warning lamp on the dash is obviously redundant now.
A question. Surely the way you’ve wired in the voltmeter will only tell you the output voltage from the battery through the bike’s circuits, not the input voltage from the reg/rec which is what you want to keep an eye on? Or am I missing something?
You are absolutely right about that! But I have worked out a way to know how I know the Regulator is working. What I see on the voltmeter is a voltage which is roughly 1.5-2 volts lower than the actual battery voltage. But what happens is that as the revs go up this voltage rises eg the base voltage I see on the voltmeter on startup is about 10.8 volts when the actual measured voltage at the same time at battery is about 12.6 volts. As the revs go up the voltage on the voltmeter rises to about 12.2 volts with the actual measured voltage at the same time at the battery being about 14 volts. This tells me the regulator is doing it's job. Hope that makes sense! I know I could have wired it directly to the battery but I did not want a drain in the battery and also did not want it to remain on distractingly all the time. Cheers
The output voltage from the battery and the input voltage from the battery are one and the same thing, they are connected in parallel. However, the further away from the battery that you measure the greater the measured voltage due to the resistance of the various joints and connections and to some extent the wires themselves. A better place to have connected the voltmeter would be between battery -ve and pin 30 of the main relay which is switched at ignition on and connects through the relay and main fuse to the battery. The shortest possible switched ignition route to the battery.
Thanks Derek, it perhaps wasn’t the best choice of words by me Naturally the voltage ‘to/from’ the battery has to be equal, it was more that the OP appeared to be measuring the voltage across the bike’s circuits rather than specifically the output voltage of the reg/rec. Your comment as to the most optimum wiring location is duly noted .
Measuring voltage 'downstream' of the battery is a good way to trace which connectors, switches, etc are causing voltage drops (= resistance) and point to what needs a good clean or replacement.
Battery technology has come a long way since they fitted old wet batteries like yours to bikes. A modern Gel would be smaller, lighter, hold its charge better and have more cranking amps (CCA).
Thanks for posting this link it saved me a lot of head scratching. In fact the whole thread has been great in helping me out.
