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03-16-2016, 07:22 PM,
#1
Several Burned up regulators/rectifiers and batteries
I bought a 1999 V-Star Custom brand new in 2000. I do not have any electrical modifications on this bike. It’s all stock in that regard.

I’ve blown several rectifier/regulator units since I bought it. I’ve also gone through a few batteries too.

Every time I have a problem, I do the usual checks. 3-Phase Stator coil voltage check, resistance of all three legs check, Rectifier/regulator output voltage check, and battery check when open circuit, and while being charged at idle/high RPM.

When there was a problem, I found either the Rectifier shorted or open, and the battery voltage soft or low. However, when I check the Stator, it reads low resistance but the same value for each leg. The shop manual says I should read in the range of 0.32 to 0.44 ohms. I get 0.2. Not trusting the digital multimeter, I used an analog meter as well. same results.

I checked the AC volts output, and each leg was about 54VAC at a choked, cold-start fast idle. When I revved the engine up more, that voltage reading went up to over 100VAC on all legs.
I thought I might have a shorted stator, so I checked all three legs to ground, nope. All checks out good there, with and Infinite reading.

So here are my questions:

Is there such a thing as too high of a Stator coil output voltage? (The OEM shop manual does not indicate any voltages, just coil resistances)
Is this rectifier problem common with other V-Star models?
Is the heat from the engine causing premature failure of the electrical components? If so, has anyone succeeded with a mod to provide cooler airflow through the regulator, and battery?


I’d appreciate any feedback. Thanks.

~wreck.
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03-16-2016, 08:21 PM, (This post was last modified: 03-16-2016, 08:25 PM by Marty8613.)
#2
Several Burned up regulators/rectifiers and batteries
Ohms was almost half expected range. That indicates over amps. Voltage might read fine. V*A=W. W = heat. That stator needs replacing.

Since you can't directly read Amps without breaking a circuit you have to go by Ohms value. Half the expected value on a coil set indicates they are at least partially shorted.

I'm thinking 15 years of build up in the stator has gummed up the coils. You might... might be able to open it and clean it out. I'd replace it though after the trouble of opening it up.

Sent from my iPhone using Tapatalk
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03-16-2016, 10:55 PM, (This post was last modified: 03-16-2016, 10:56 PM by Vstarwreck1999.)
#3
Accept  RE: Several Burned up regulators/rectifiers and batteries
(03-16-2016, 08:21 PM)Marty8613 Wrote: Ohms was almost half expected range. That indicates over amps. Voltage might read fine. V*A=W. W = heat. That stator needs replacing.

Since you can't directly read Amps without breaking a circuit you have to go by Ohms value. Half the expected value on a coil set indicates they are at least partially shorted.

I'm thinking 15 years of build up in the stator has gummed up the coils. You might... might be able to open it and clean it out. I'd replace it though after the trouble of opening it up.

Sent from my iPhone using Tapatalk
Well, that is why I'm here. To get some good advice, and what you said makes perfect sense. I don't know why the shop manual doesn't give specific details like the expected voltage range from the stator, but 100+VAC seemed way too high. I am going to buy a new stator, voltage regulator, and battery. I will keep this thread updated with my progress.

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10-12-2017, 07:29 PM,
#4
RE: Several Burned up regulators/rectifiers and batteries
Ok, so it's been awhile, but I thought I'd update the status of my '99 V-Star XVS1100 Custom. 2017 marks the first year that I have not had insurance or a bike on the road since 1987. That sucks. Blew my last Rectifier/Regulator blew open with such intensity there were two holes through the epoxy on the backside. I had replaced the Stator, R/R, and battery all at once. This combination lasted only 2 months and blown again. Battery boiled and melted, R/R literally blown open.

Work was done at a Yamaha Authorized Repair Centre, and OEM R/R was used. Stator was from RMStator.com. The bike is in the garage on a jack while I try to find out if there is a short somewhere in my electrical system. Yamaha says there is no 'known' issue with R/Rs overheating at their current design location, which is behind the exhaust pipes, and behind the engine. Personally, with a R/R design that dissipates excess power as heat, placing it here seems retarded. I had tried to relocate the R/R, but again, that particular R/R didn't last more than a few months either.

I'm at a loss. I checked the main buss fuse, and when the key is on, there is a 1.1ohm resistance reading to ground. Pulling the headlamp fuse eliminates this low reading. Now, before you ask, the headlamp was removed/unplugged as it blew when the last R/R popped. The front turn signals have dual filaments, which one on each side are illuminated as soon as you turn on the key. The low resistance reading is coming from those signals, but I'm not sure if 1.1ohms is too low, or typical. Therefore, I'm not sure if I'm on the right path or not.

Does anyone else have something they can suggest to search for, as a culprit to over 6 R/R and several batteries going bad for this bike? I'd like to ride again!
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