It would be helpful to know what year you're referring to here.

The Gen 3 had a recall on them due to the placement behind the motor with no cooling. The Gen 4 are pretty solid. If they fail, they usually stop outputting power so the battery will die as the bike will be running total-loss from battery.

I think you're a bit mistaken though. The purpose of the regulator/rectifier is two-fold. It first rectifies the variable AC voltage from the alternator and then limits the output to recharge the battery. This is done to maintain a CONSTANT voltage out of the rectifier. It should not change much, if at all, while revving the motor. That's why it's there. The alternator will change drastically though based on RPM and will read about 46 volts AC at 4,000rpm. At low idle, the voltage will drop slightly, but anything over 14 volts would be considered normal.

Remember, this is a 12 volt, negative ground system. The electronics are designed to run on 12 vDC and the extra voltage from the rectifier is used to recharge the battery while running.

Lithium batteries are not the same as lead acid. They are easily damaged and rapid charging them improperly can hurt them. Also, allowing the voltage to fall below a certain level will also render them useless. And while everyone thinks about voltage, it's the amperage that's important. Lithium are not known to be able to sustain the amperage for long periods of time. Did you hit the kill switch to stop the motor and leave the key on? That would mean the headlights were running and you could kill the battery right quick waiting for the train to go by.

It sounds to me like you need to not kill the motor while stopped for trains. And if you do, make sure the key is off. Everything you've posted leads me to believe everything is working as it should so you should monitor the situation closely before worrying about fixing anything.

 

This is done to maintain a CONSTANT voltage out of the rectifier. It should not change much, if at all, while revving the motor.

Copied right out of the Service Manual:

Charging Voltage
Connections

Tester Range
Tester (+) to Tester (–) to
Reading

DC 25 V Battery (+) Battery (–) 14.2 ∼ 15.2 V

•Turn off the ignition switch to stop the engine, and disconnect
the hand tester.

If the charging voltage is kept between the values given in
the table, the charging system is considered to be working
normally.

If the charging voltage is much higher than the values
specified in the table, the regulator/rectifier is defective
or the regulator/rectifier leads are loose or open.

If the charging voltage does not rise as the engine speed
increases, then the regulator/rectifier is defective or the
alternator output is insufficient for the loads.

Check the alternator and regulator/rectifier to determine which part
is defective.

 

I'm guessing everything is OK and the simplest explanation is that I had a slightly loose battery ground terminal, snug but probably a slight amount of surface corrosion between lug and terminal causing high resistance. I cleaned them up and retorqued and will ride in the morning. The battery is definitely charging now so we'll see.

 

Rode it about 40 miles this morning, no problems, guess it was a slightly loose battery terminal.

 

I've had two fail so far on my gen4 racebike. Symptom after the first one failed was a dead battery. Once the second one failed it kept on popping the main 30A fuse after a couple seconds of being started. Can't remember what voltage it was reading but I narrowed it down to the R/R

 

My question is, has anyone had a regulator-rectifier unit fail and how did it fail? Did it overvolt and smoke the battery or have low output and ran the battery down etc.?

I lost one on my former Duc...

first I noticed my dash back light and signals were out when I turned into a destination parking lot. No symptom when I fired up. A few rides later, same thing. power cycled the bike, lights came back. I got home, replicated by letting the bike idle. googled and found that this set of symptoms matched up with the ubiquitous Ducati V/R failure. I checked the gauge and saw 16+ v on the instrument cluster and shut it down - it was still climbing on the cluster gauge when I shut it down.

Using the gauge cluster as a guide, dash lights, signals, horn, etc. scrammed at about 16.4 on the dash. I bought a new battery - a shorai - as a test, that didn’t help, rode back to the dealer. I saw the volts on the gauge reach 18.0 before I got back. They I picked up a Yamaha v/r - reported to be better than the cheap Ducati unit and replaced myself, but by this time, the shorai was fried. That battery had only been over-volted twice and for a very short time, but it was apparently enough.

If you use a trickle charger, you will likely mask a problem. Leave the bike off the charger for a few days and re-test the voltage.

 

Thanks for the input folks, the WPS lithium battery appears to be holding a charge fine now and the ride went well yesterday. Highest regulated voltage I've seen is 14.71 V, range is 14.2~15.2, so it appears that the regulator-rectifier is doing it's job. I'm assuming a bad connection at the battery terminal right now with no other explanation available as to why it quit. I'll keep an eye on it over the next few rides.

 

Hmmm.....first ride went fine but on my second ride this morning my bike wouldn't start again after a stop to refuel. This time I was lucky and there was another rider who helped me get it bump started and rode home without further incident but the battery was completely dead when I arrived home. Haven't checked the charging system voltage yet but will pull the battery out and get a new one and check the R-R charging voltage again. Not sure if it's the battery that failed, 9 month old WPS Lithium battery, or the R-R unit is over Volting and damaging the battery. I ran the bike for quite a while with a voltmeter on it and the charging system volts were in spec at 14.67 Volts so don't know what is going on here.

 

Well, I pulled the seat off and the battery was showing a full charge on the LED charge indicator on the WPS Lithium battery and about 13.2 Volts under no load so it sounds like the battery was still charged. When I engage the starter, I can hear a very rapid buzzing sound coming from the starter solenoid. I put the battery on a charger and brought it up to 13.8 volts, same thing, no start and starter relay is still buzzing and battery voltage is dropping to 6.7 volts while starter switch is engaged. Soooo.. I either have a bad battery that is unable to deliver current under load or a bad starter motor.

 

Yes, the reg/rec will die. If you can get your nose on it, it will smell like burnt electrical equipment if it's toast.

lost 2 on the CBR.

they get hot and burn up, make sure they are clear of any obstructions or air flow restrictions.

what you describe is the classic reg/rec fail battery dies, charge it up, run the bike... battery dies.

If it were the gen coils, the bike wouldn't run on a bump start, really with the reg/rec toast the bike shouldn't run on a bump start. But if you let the bike sit for a bit, the battery may have had a little life in it, enough to get you home.

get a new reg/rec They do go.

 

Thanks for the insight Rifleman, one final question I am curious about though. In your experience, when the R-R unit goes out, does it go high or low voltage output and does it just quit completely or sometime work and sometimes not depending upon temperature?

This battery also has me scratching my head as it shows an apparent full charge but nothing but relay chatter with starter on, like it's got a couple of dead cells.

Thanks!

 

well it depends on what fries first.

if the Regulator goes, your voltage will go high (actually had that happen on my GS550) the Headlight would go really REALLY bright and then finally burn out. I burned out dash lights, turn signals, just about every light.

the regulator part limits down stream voltage to like 15 volts and dumps the rest to ground, that's why they get hot. When you are running under 5 or 6k RPM, the generator isn't producing enough to feed the loads so the battery covers the loads, but as you cruise down the road at 8k RPM for 25 minutes the generator is over producing so the reg/rec is dumping that extra to ground.

If the rectifier burns out... no voltage/amps are being lined from the generator and line voltage is what ever battery voltage is.

So it can do either, high or low/none voltage.

and it can fail, then cool down, and work again (for a bit) so it's a tough one to track down.

but you have the classic symptoms... a good battery that suddenly goes dead for no good reason, and a bike that just dies out of no where. My CBR died at 60mph on the highway when the first reg/rec went.

hope that helps

 

Put in a new OEM Lead-Acid battery this morning and it cranked right up, the WPS Lithium is smoke apparently. Shows good open circuit voltage but then dies under cranking loads. Regulator-Rectifier is toast also , showing zero charging now, sure hope it didn't take out the generator coils along with it. I'll have the R-R unit replaced under the recall and see if that doesn't fix the problem. I doubt they will warranty the generator coils if it smoked those also.

 

Rifleman, when your R-R failed did it smoke the generator stator coils? I'm trying to piece all this together and it appears mine may have failed to the high voltage side rather than low voltage side. If it had failed to the low side it wouldn't have killed the lithium battery I'm guessing. If it failed high, it probably took out the battery and then running wide open might have taken out the stator coils with it. After the first time it died, it was showing a solid 14.67 volts charging system voltage so well within specs. I saw no evidence of either over or under volt until now. Only way to know for sure now is to get a new regulator and see if it's going to charge. Stator coils run about $300, regulator is $259, expensive stuff!

 

OK thanks Rifleman, I called the dealer and gave them my VIN number and they ordered me a new reg-rectifier unit under the recall, no charge for parts or labor. They said I can make an appointment and bring the bike over and they'll change it while I wait, the Service Bulletin calls for.4 hours labor. Now he wasn't sure if I smoked my stator coils, the Service Manager said they typically don't but we won't know for sure until I get there and they get the new R-R unit on there. I checked the lighting this evening and it blew out both low and high beam headlights but the rest of the lights and instrument gauge cluster seemed to be working fine.
Did you smoke the stator coils on your GS-550 when it went high or just the headlights?

 

stator coils stayed good on the GS. just when the voltage regulator crapped out, the line voltage jumped pretty good depending on engine RPM. I think it's tops out at like 70 volts at 10k RPM at least on the Zukies.

cooks your battery too... super over charge.

it's a quick and easy, two bolts hold it on, plug and play. should be under the seat or on the side near the pillion seat, not sure of the location on the 10R but they have to be somewhere that gets some air flow, cuz they do get hot.

this is the CBR Reg/Rec, notice the little "spot" where the magic escaped.



this is the old and new, on the CBR it's on the right side, behind the faring near the pillion seat.

 

Hi Rifleman, thanks for those pics. I'm anticipating the worst case scenario now and thinking my stator is cooked, reason is the charging output has now dropped to battery voltage, 12.60 volts, zero output from the charging system. My Reg-Rectifier unit failed high and then went to zero, so I'm guessing to do that it must have shorted the stator coils out. I can't see anything in the R-R unit that would fail and shut down all voltage to the charging system unless all six diodes in the bridge rectifier opened. That is a possibility I guess, only way to know for sure is pull this thing apart and check the stator output voltage at the R-R unit. The Service Manager said the output should be about 70 volts AC across all three phases taken in pairs when revved up and the voltages should be very close between the phases. I'll keep you posted on how this all turns out. Man I wish I 'd taken it in early and gotten that R-R changed when the recall first came out. My thoughts were I've been riding it for 7 years with no issues, maybe I dodged the bullet...lol!

 

Update: My dealer replaced my voltage regulator/rectifier under a recall on Tuesday morning and the tech told me the bike is now charging fine, rode it home without further incident.

The reg unit was melted down, had a hole similar to the Rifleman photo.

The reg apparently failed to high voltage and smoked my lithium ion battery and blew out both headlights.

 

Glad you got it sorted, it's one of those things that feels like you have gremlins in your bike because all kinds of stuff goes sideways, burned out head lights, battery after battery goes bad (or so it seems).

now ride and enjoy