Hi

My RVF has a charging problem. It occured a day when I had done 200 miles. Suddenly wouldn't go over 7k rpm until it died on me. Conclusion was no power on the battery.

It charges around 12,4V when lights are on. Disconnecting the two front and one rear bulb results in 13,3V charging. The bike rides ok with this charge, so no riding in the dark

I have tried changing the rectifier to another (that I know work). Still the same. Measured the winding resistance in the generator, seens ok.

Any suggestions? Could it be a battery that need changing?

Kind regards
Martin

Now, if generator is ok, rectifier is ok, then why the hell won't it charge more.

At what rpm did you measure the voltages. 12.4V with lights on at idle is typical, you need about 3000 rpm to get 14V with lights on. What battery voltage do you get at 5000 rpm. Check the wiring from alternator to rect/reg for bad connections. Would the engine crank over using its own battery after it stopped. How old is the battery.

12,4 is at 5000rpm

When it stopped it wouldn't crank over. Not even lights were on. Don't know how old the bat is?

When I drive with the lights on I can ride for almost an hour, then it starts sputtering over 7k rpm. Then unplug the bulbs and it rides ok again.

put a new battery on to rule it out but did you test the generator output?

its AC voltage, disconnect it from the reg rec and measure between the 3 yellow wires.

even then it could be breaking down under load but see what ac output you get first

What state are the connectors for the reg/rec and the alternator in? If it's still got the original ones fitted, they've probably become full of road grime and the wires tend to corrode. Output from the charging system gets lost due to extra resistance in the circuit, and it has the handy side effect of damaging the connectors, and making everything worse!

So...

Changed the battery. With all bulbsplugged in it now is up to 13.3V and 13,7V with only one head light bulb.

Connections to the reg are checked and all good. Wirering from altanator plug to reg show under 1 ohm resistance, so they're good.
AC voltage between the 3 yellow wires from the altanator. At idle they're showing 14V. At 5000rpm they show 38-40V.
The Haynes manual doesn't state what voltage the altanator should have, anyone who knows?

Kind regards
Martin