Charging system failing, safety relay suspected

[davekeck]

Hello! I'm having a charging issue with my 1982 XS650J and was looking for some feedback on my assessment.

Problem Background
My battery isn't charging because the voltage at the battery is 10.5V at idle and 12V at 3k RPM. When I unplug the yellow connector for the safety relay, the battery voltage is 11.2V at idle and 14V at 3k RPM.

What I've Tried
- Replaced alternator brushes recently and the lengths are within spec. Brushes assumed OK.

- Tested the regulator (grounded green regulator lead; no increase in voltage at battery at 3k RPM) and alternator brush wiring (connected brown brush lead at alternator to positive battery terminal; no increase in voltage at battery at 3k RPM). Regulator and brush wiring assumed OK.

- Resistance between rotor rings, brushes removed: 1.6 ohms (rotor assumed failing)
- Resistance between rotor rings and ground, brushes removed: infinity
- Resistance between white-white leads: 0.5 ohms

- Resistance between white leads and ground
-- Yellow connected: 22 ohms
-- Yellow disconnected: infinity

- Voltage between white leads at idle
-- Yellow connected: 8.6V AC
-- Yellow disconnected: 9.4V AC

Questions
To me these measurements suggest:

1. The yellow wire is grounding the white stator wires, reducing the alternator's output.
2. The rotor is failing based on the 1.6 ohm measurement, but works to a degree since it can still deliver 14 volts at 3k RPM.

Is this a plausible assessment? How can I prevent the yellow wire from reducing the alternator's output?

Thanks very much!
David

 

[retiredgentleman]

First thing................the Safety Relay is not defective. The 22 ohms you measure is the resistance of the Safety Relay coil, and that is normal.

Yes, your rotor has some of the windings shorted out, so it reads 1.6 ohms when it should read about 5 to 6 ohms. The rotor is producing a very weak magnetic field, and thus you are getting only 12 volts at 3000 rpm, which means you have no charging whatsoever.

8.6 volts AC at the white stator output leads is low, since normal is about 12.5 volts AC.

Its time to get a new(rewound) rotor. www.customrewind.com in Alabama is known for quality rewinding.

Other sources of rotors such as Mikesxs or E-bay may work, but there are reports that the rotor face with the slip rings do not always run true.

If you are using the stock TCI black box, you need to have the 80 to 83 rotor that has the small magnet embedded on the edge of the rotor. Just mentioned this in case you look at used rotors on E-bay. The 70 to 79 rotors don't have the embedded magnet, and would not fire the ignition.

 

[davekeck]

Thanks for your help!

I read in one of your old posts though:

You measured 0.7 to 0.9 ohms from white to ground.................should be infinity.​

I measured 22 ohms between white and ground (with the yellow wire connected.) Is that not a problem?

EDIT: I just realized that you have to disconnect the 6-pin connector before taking the measurement between white and ground. I'll do that next, but before I need to get some sleep =)

Thanks again for your help.

 

[jamesgs4]

There is a reason why the PMA conversion is so popular, and it is because the factory charging system is shitty. I wouldn't waste any money on trying to fix the old crap.

 

[davekeck]

Yeah I'm seriously considering a PMA kit - especially if I'm going to replace the rotor anyway. Still getting my toes wet though with the XS650 electronics...

 

[jamesgs4]

I got stranded on a road trip to mexico because I trusted the factory charging system too much. I wish I would have done the conversion sooner. If you get one, buy from hughshandbuilt, he is the best out there. Since you have an 82, you will need an ignition system. A Pamco is the best for that, too. Those 2 improvements were the best things that I have done to my xs.

 

[XSLeo]

You can spend about $300 for the PMA, $250 on the Pamco, or About $125 on a rewound rotor.
I think I might try the rewind. It will fix your bike and save you money.
The PMA is an ok conversion, but not always the best option.
It's popular because people want to run without a battery and is hyped by people that think it's better without really understanding the stock set up.
Leo

 

[retiredgentleman]

Thanks for your help!

I read in one of your old posts though:

You measured 0.7 to 0.9 ohms from white to ground.................should be infinity.​

I measured 22 ohms between white and ground (with the yellow wire connected.) Is that not a problem?

EDIT: I just realized that you have to disconnect the 6-pin connector before taking the measurement between white and ground. I'll do that next, but before I need to get some sleep =)

Thanks again for your help.

Yes, to measure resistance from whites to ground, you need to have the 6 pin disconnected and the yellow wire disconnected.

 

[retiredgentleman]

There is a reason why the PMA conversion is so popular, and it is because the factory charging system is shitty. I wouldn't waste any money on trying to fix the old crap.

This is a very typical response from riders that have purchased a PMA for their bike. Once they own one, they become cheer leaders for the PMA system. I totally disagree with your statement that the factory charging system is "shitty". I have used the stock system for the last 5 years, including longer trips, and it works very well.

The fact that any charging system works for 30+ years, in a very hot,vibrating engine,is a testamonial to the amazing durability of the factory system. Its a fact that electrical components (factory or aftermarket) are likely to fail after 30+ years. My OEM stator and rotor are 34 years old, and I'm confident to keep using it this season. Could it fail this season..................of course it could fail this season. However I will continue to use my factory system until it fails.

As XSLeo pointed out, you can spend a large amount of money (and become part of the cheer leader team) or you can spend a small amount, but in the end its still just a means to charge your battery.

 

[weekendrider]

but in the end its still just a means to charge your battery.

All this electric stuff and the smoke that makes it work is magic to me!
But I do have a question.
Wouldn't the condition of the battery relate to the life of the rotor/stator?
Continually running a battery with a dead cell or marginal charging ability causing the components to work overtime and the overheating?
My take on why the stock components are in such poor condition today.

 

[jamesgs4]

Cheerleader? What the fuck is that all about? You mad because I am happy with my charging system?

pros of the PMA
1. no wear parts
2. only moving parts are the magnets
3. simple, new wiring
4. Easy to install
5. It is a proven, reliable system used on the banshee for many years
6. batteryless is an option
7. maintenance free, install and forget

cons:
1. Initial cost is more than a rotor rewind
2. Old farts don't like it because it is a change, and you know how old geezers hate change.

Pros of the factory charging system:
1. it is free with the bike
2.....crickets

Cons of the factory system
1. it is 30-40 years old
2. 2 brushes to wear out, not readily available, you have to order them
3. the most delicate part(the rotor) is spinning at a bajillion rpm
4. it is weak even when operating properly
5. cannot run batteryless
6. to replace all of the old components with new ones is just as expensive as a PMA conversion, and it still will need continuous maintenance
7. It will leave you stranded when it fails, not IF if fails

 

[grizld1]

Weekendrider, affirmative. The regulator in the OEM excited field system operates by cutting power to the "hot" brush, giving the rotor windings a cool-down break. With a weak battery, this never happens.

Both the OEM excited field and the PM systems have their virtues and vices. I use a Sparx 3-phase PM system, but for only one reason--Michael Morse of 650 Central and Bill Getty of JRC Engineering gave me one in exchange for blueprinting the installation on the XS650.

PM systems aren't foolproof. The main drawback is the fact that they require the use of a load-dump voltage regulator which, under sustained high-speed use, can get hot enough to cook itself and/or the rectifier diodes in unit reg/recs. The key to keeping on the road with them is to dump enough current during high speed use with high wattage accessories to help the regulator; turning on a high beam of 100W or more will usually do it. I also use a halogen tail light bulb if I'm going to be running down the Interstates for any length of time. Load-dump regulators also tend to be noisy, producing more EMI and EFI than circuit breaking regulators, but that's usually not a problem unless you mount the regulator right on top of an igniter box.

 

[davekeck]

Hi all, thanks for your feedback and comments.

I re-measured the resistance between white/ground with the 6-pin connector disconnected and got infinity as expected, so all signs point to the rotor.

I'd jump on the PMA if the whole shebang cost ~$250, but seeing as I spent $1000 on the bike I'm not sure if I want to spend $500+ on a new charging system and ignition. I do like the simplicity of it though... need to do more research.

Thanks again all, especially retiredgentleman. I'd be lost in an ocean of ohms, relays, and error-filled Clymers without you =)

David