Charging Issue - Stator Voltage Check

[CBJoe]

Hello Folks,

Done lots of searching and just need a few clarifications while troubleshooting a charging issue on my '07 Bonneville. Classic charging issue where battery goes dead after long period of riding. Pretty sure the Regulator/Rectifier has gone kaput, but here are my voltage numbers

Key Off: 12.6V
Key On: 12.3V
Idle (1400rpm): 14.2

While reving the engine to 2-6k voltage drops to 13.5V and never goes up or down from there. So system is not charging the battery while riding.

This tells me Regulator/Rectifier but I want to confirm my Stator measurements:

Across all 3 phases I get 16V at Idle and upwards of 80V and high revs. Looks good to me, but I have found reference to the 16V being lower than expected voltage at idle.

Is this normal output from the stator at appx. 1500rpm?

Cheers, Joe

PS...battery is getting replaced regardless as I dont trust it much since it was totally drained multiple times while stranding me at least 3 times with this charging issue. Will keep it around as a backup.

 

[normandy]

I had a lot of stator trouble until I turfed the regulator and got a mosfet reg /rec.

I forget the details now but there is a simple ground test you can do with a multi-meter at the plug under the seat on the stator wire. The test is in the Haynes manual. It is a 3 phase alt. so you have some pin to pin readings to take as well. Regardless of the stator tests, I would definitely change the regulator, I didn't and burned 2 more stators over 3 years.

 

[CBJoe]

Thanks. I think that test looks for a short to ground on one of the phases. I'll check that but I don't think this is the case.

I will likely order one of the MOSFET Reg/Rec from regulatorrectifier .com ......unless someone has another recommendation for where to order from.

Do you remember if there is a diode test to do on the Regulator/Rectifier to sure?

 

[CBJoe]

Ok...Finally found some other references of the voltage across the leads of the Stator at idle. Looks like 15-20VAC at idle is ok.

I'm going to take this as the case unless someone else counters this.

Regards, Joe

 

[Baltobonneville]

Just replace it. The OEM regulator-rectifier is marginal at best. Rick's motorsport electrics has one that is plug-and-play, if you want to make it easy. It's also smaller and blacker, looks slightly better. Your battery will last longer too.

Addendum: If you order from Rick's, you want the upgraded regulator-rectifier, not the OEM replacement.

 

[bonZa]

Hello Folks,

Done lots of searching and just need a few clarifications while troubleshooting a charging issue on my '07 Bonneville. Classic charging issue where battery goes dead after long period of riding. Pretty sure the Regulator/Rectifier has gone kaput, but here are my voltage numbers

Key Off: 12.6V
Key On: 12.3V
Idle (1400rpm): 14.2

While reving the engine to 2-6k voltage drops to 13.5V and never goes up or down from there. So system is not charging the battery while riding.

This tells me Regulator/Rectifier but I want to confirm my Stator measurements:

Across all 3 phases I get 16V at Idle and upwards of 80V and high revs. Looks good to me, but I have found reference to the 16V being lower than expected voltage at idle.

Is this normal output from the stator at appx. 1500rpm?

according to the trouble shooting guide in thew FSM.
at idle you should see a minimum of 10v ac or a bit over, at 4000rpm and above, 30 volts ac.
as you are seeing 80 v at the higher revs and being way above the spec 30 volts ac, this indicates a dodgy rectifier

 

[Roger]

as you are seeing 80 v at the higher revs and being way above the spec 30 volts ac, this indicates a dodgy rectifier

I think he is saying there are 80 volts at the 3 yellow wires ahead of the regulator / rectifier. If there was that much voltage coming out of the R/R, everything connected behind the R/R would be 'crispy critters'.
The regulator knocks the voltage down to ~15 volts for the rectifier by shunting / shorting excess voltage to ground. The rectifier smooths the choppy pulses (using condensor or capacitor) coming from the 3 stator windings and limits the output to charging voltage (diodes or zener diodes) with positive and negative outputs.

I don't know if 80 volt peaks coming from the stator is normal for these bikes, but too high voltage, will cause excessive heat for the regulator because it has to shunt so much extra current to ground. This will also make your connectors brown and cause burnt spots in the terminals. Old, tired terminals can also cause arcing, leading to connector failure (typically seen at headlight connectors with upgraded headlights). You can't just bend terminals 'tighter' like a loose spade terminal. Once they are loose, they are most likely annealed from too much heat or age, and will stay soft and loosen up again. Heat kills electronics.

In this picture, Alternator is the Stator with the 3 legs or 3 yellow wires.
S1, S2 and S3 are SCRs. These are responsible for dumping any voltage above the charging voltage, to ground. They get hot from doing their job. If the voltage coming from the stator is higher than normal, this will heat the SCR even more and cause it to fail. This will then lead to a direct short to ground or the SCR will 'open' or not conduct at all. If the SCR shorts, it will create more heat in the stator winding that is connected to that SCR. If the SCR is 'open', this will show up as a decrease in charging voltage at the rectifier output wires.

The windings in the stator are bare copper wires coated in a thin layer of enamel or varnish. The heat breaks down the coating and the tightly wrapped copper wires begin to short against each other.

MOSFET R/R units are better because they are way faster than SCR units. Their speed at opening and closing the 'g' or gate means that they run cooler. That is their advantage.

Be careful when buying a new R/R. Don't get some cheap piece of shit from china just because it saves you $50. Ask where it is made and check the terminals. If the terminals look thin and are a brass colour, be wary. Those tin terminals will fail in no time at all. If you need to get new terminals, I would start by calling local auto shops that specialize in alternator and starter repair and rewinding. They might stock terminals that will work in some typical motorcycle stator connectors. You might even ask if they can rewind your bike stator for you. Some old school shops can do most anything like that.

Sorry for the ramble, it's still not spring here and I have too much time on my hands. GO GO GADGET SPRING!

Death to all snowmen.

 

[CBJoe]

Thank you for the replys. Thanks Roger for the details. Purchased a new MOSFET regulator from Ricks and it should arrive today. Plan to install and test tonight.

BonZa...I have the Factory Service Manual, but missed that in the troubleshooting section. I think I need to grab a beer and flip through to see what other helpful info I may have missed. Thanks.

Regards, Joe

 

[CBJoe]

Resolved with new MOSFET R/R. Seems to be charging properly. 14.5V above 2000rpm. Will put some miles on it over the next few months to see how it holds up.

Cheers, Joe

 

[Baltobonneville]

We've seen enough reports of starting and "battery" problems that were resolved with a new regulator-rectifier that it would seem a good idea to replace them proactively. The same problem also has been reported in other Triumphs that use the same r/r.

 

[travellingtenor]

We've seen enough reports of starting and "battery" problems that were resolved with a new regulator-rectifier that it would seem a good idea to replace them proactively. The same problem also has been reported in other Triumphs that use the same r/r.

Good posting. I purchased a Rick's R/R and will install it tonight. I have never been stranded but I thought that I might as well replace the stock R/R before it let's me down. Sitting on the side of the road is a really bad thing.

 

[travellingtenor]

Well, looks like the R/R was the problem. Installed the Rick's R/R and everything checks out fine. Showing 14.7 at to the battery at 1,500RPMs. When I tested the system with the stock R/R in it the R/R got so hot I could hardly hold it. The new one did not get hot at all during my testing. The new unit is a little smaller and is painted black that goes with the rest of the bike. Now all I need to do is get a new battery since the battery in the bike is at least six years old. That is a long time in the environment that I live in. Batteries don't last long in the hot desert.

 

[TC_Dick]

Well, looks like the R/R was the problem. Installed the Rick's R/R and everything checks out fine. Showing 14.7 at to the battery at 1,500RPMs. When I tested the system with the stock R/R in it the R/R got so hot I could hardly hold it. The new one did not get hot at all during my testing. The new unit is a little smaller and is painted black that goes with the rest of the bike. Now all I need to do is get a new battery since the battery in the bike is at least six years old. That is a long time in the environment that I live in. Batteries don't last long in the hot desert.

If you don't mind me asking, what's up with your seat there? looks like it flips up..

 

[travellingtenor]

If you don't mind me asking, what's up with your seat there? looks like it flips up..

Yes it does. I got tired of messing with the stock seat retention system and went looking for something different. I always thought that the flip up seat on the old Triumphs was a pretty good idea.
Well a company called Farley & Ace Inc must have thought the same thing and they designed a kit that works great. They have modified their system since I bought mine and I have added a wire retention cable.