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Lazy Charging.

Discussion in 'The Garage' started by MacMcMacmac, Jun 14, 2020.

  1. Rotor ohms out good. 5.9-6 Ohms. I replaced the slip ring plate with a newer, much smoother one rescued from the Rick's alternator I fought with a couple of years ago. The neo magnet I installed is working perfectly. I paid no heed to polarity when I installed it so I can't give you any guidance on that matter.

    Brushes are well within useable length range.

    The regulator test, such as it is, checks out. More than 10X the resistance when checking each white wire lead between the red, then the black wires. I assume this is just a diode test and doesn't really tell you a whole lot about how well the regulator is actually functioning.

    The output remains unimpressive. Bringing the motor up to ~4000rpm sees voltage levels just barely crack 13V, which I guess should be enough. I bought a "Chrysler" regulator a few years ago. Maybe it's time to give it a whirl. Just need to get a couple of bridge rectifiers. Details of wiring the reg are a bit hazy now. I have a two wire plug and three outputs from the regulator. I'll have to do some sniffing around.
  2. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Have a sniff here.
    Team Junk likes this.
  3. Thanks Jim. Unfortunately I have the older pack-of-cigarettes-on-a-Dodge-Aspen-firewall style regulator, not that sexy Italian Fiat jobbie that came along later. I am sure when I bought it that it was the required type for my 83 Heritage. I wish I had been as thorough before I spent $40 on a front rim with XS750/850 Special brake rotors on it a few weeks ago...

    It's not as compact as I would have liked so I might just get the shiny one anyway. How is the voltage/rpm response on your setup? Peak voltage?

    Jim likes this.
  4. Got it.

    From PamcoPete on another thread:

  5. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Idle is at or slightly above batt.... 12.6 - 12.8V. about 14.5V at 3000rpm.
  6. 5twins

    5twins XS650 Guru Top Contributor

    Yes, Pamcopete originally came up with this swap and the Chrysler regulator was his recommendation. I stumbled upon the Fiat unit several years later on eBay. It was the required "A" type, very reasonably priced, and cool looking to boot. It's kinda become the standard unit to use for the swap now.

    What you've tested by checking between the 3 whites and the red then black is the rectifier portion of your combined reg-rec. I'm not sure there is an actual test for the regulator portion other than to disconnect it and ground the green wire from the outer brush full time. This will turn the alternator on full blast and rule out problems with it (if it's output does indeed go up), pointing you to the regulator as the issue.
  7. Sounds ideal!
  8. Thanks 5Twins. I'm trying to figure out if there is a way I can come up with a hybrid system that uses the rectifier in the stock regulator and uses the new regulator for, um...regulation.
  9. Team Junk

    Team Junk XS650 Junkie XS650.com Supporter Top Contributor

    Don't think that will work . Do suggest the 3 phase windy nation 3 phase rectifier. One unit replaces the 2 single phase bridge rectifier.
    Jim likes this.
  10. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    One advantage with the 2 single phase rectifiers in line is on the off chance a diode shit itself there is a spare diode.
    Team Junk likes this.
  11. 5twins

    5twins XS650 Guru Top Contributor

    Yes, you can still use the rectifier portion of your original reg/rec if it's still good. Only hook up the wires that lead to it (3 whites, red, black). The other two wires in the harness plug (brown and green) will get connected to your new regulator.
  12. Aha! Thanks. I vaguely recall discussing this a few years back. It will be a quick way to test if nothing else.
  13. Regulator is installed and working fine with the oem diodes. I pulled the green and brown wires from the harness side of the plug and soldered the new regulator bottom lead to the brown wire and the upper left to the green wire and then pushed them back into their slots. Then I pulled the green wire out of the regulator side of the plug and moved it to an unpopulated slot in the plug so it would no longer be in the circuit. Charging is working normally now. I drilled and tapped two mounting holes on the right side of the battery box then ran a dedicated ground from one of the bolts to the main ground lug. I originally went to one of the left over screws from the safety relay only to find they were part of the rubber mounted battery box and provided no ground.
  14. Well, I'm at a bit of a loss. I thought everything was working well. When I started riding yesterday I was happy to see my digital voltmeter reading up to 14.7V as I rode. This was a nice change from the 12.5-13V I was getting. Unfortunately,on my way home, charging went back to a max of 12.7V no matter the rpm. I was reading as low at 10.8V when I was idling at a stop.

    I had shut my bike off while in town in order to gas up. I thought I was maybe losing a few volts through the harness to my connection point to the brown wire inside the headlight, so I connected my voltmeter directly to the battery when I got home and found the same output right at the terminals. I thought perhaps it was a heat related intermittent fault with the stator. I disconnected the plug to the alternator and found the stator coils all within spec 0.8-1 Ohm phase to phase. The bike was still hot at that point, so I can rule out a heat related opening in the stator windings. The Chrysler regulator is obviously capable of producing the goods as my 14.7v readout would attest to.

    Looking through the manual, it seems the brown wire gets fed through the ignition switch right from the fuse box. I could see how a bad contact inside there could perhaps make a good connection one time, and a lousy connection another time. This would coincide with my shutting the bike down at the gas station. It seems to me that the loss of up to 4V through the switch would have something smoking though, since there is so much connected through it. I am scratching my head on this one.

    Yet another fine write up. This site is like an encyclopedia!

    Last edited: Jun 28, 2020
  15. No dice on the switch. It was pristine inside.
  16. I think I found the non-smoking (thankfully) gun. I measured the resistance between the brown and green leads and was shocked to find 60-70 Ohms instead of the 5 -7 Ohms called out in the manual. I was perplexed since I didn't have an explanation as to why the resistance was so high between the brushes, since they were quite serviceable length wise. I redid the solder joints as they seemed a bit small I took them out and cleaned up the wire lugs and cleaned the angled tabs the brushes mount to.and got down to about 26 Ohms. This surprised me as they did not look that bad at all, just a slight tarnish. I pulled the brushes again and thought that one brush spring seemed a bit lazy, so I stretched it a bit to get more load against the slip ring. The real problem is the copper leads connecting the brush to the tab had frayed considerably, so that a small core of copper wire was trying to carry all the magnetizing current for the brushes. I gathered them together and soldered them. I am now down to 11 Ohms. Much better, but still out of spec. So it looks like new brushes are in order. Just goes to show you that just because the brushes are ok for length, there can be other issues with them.
    Jim and Team Junk like this.
  17. Well, I went for a decent run and I was disappointed to see 12.5V for a long while. Once it came up to around 13V, it seemed to climb quite a bit quicker. It eventually hit a healthy 14.5V. I thought about it and figured it was a classic case of not getting more out of a system than you put in. So while the battery was charging, the available current for the rotor was limited, and charging output was also therefore limited. Voltage would fall to 12V or so at idle, then recover with rpm, but kind of slowly. You guys with a healthy system, do you get your max output right away when you rev your bike? There seems to be quite a lag in mine, it gets there eventually, but it's none to swift about it. For now, I will put it down to the excessive brush resistance. I'll keep investigating for now. It still seems laggy. I am close to throwing a new battery in there to rule that out as well.
  18. Well, consider this one solved.

    After 2 beers and thinking a bit, I went and measured the brushes again and got 30 Ohms. Well, that sucked. I pulled the brushes again and measured the resistance of the brush from tab to tip and found negligible resistance. The rotor ohmed out ok, so the resistance had to be at the brush/slip ring interface.

    I looked at the end of each brush and had an AHA moment when I realized there was just a crescent of contact on each. Then I remembered the process of bedding in new carbon brushes on the big synchronous motors at work, where you pull some glass abrasive paper between the brush and the slip ring to give the brush wear surface the proper arc of contact to minimize current density at the brush face.

    Since the brushes in the alternator are a slip fit in the holder, they will lean a little as they are pulled to the side by the slip ring rotation. If the brushes are not put back in exactly the way they were taken out, the now angled brush face will be oriented in a new direction, and you will no longer have full contact with the slip ring. So, I figured the best thing to do was reestablish a square end on the brush and let them bed in again.

    I did this by using an adjustable square. I pulled the ruler even with the base of the square, then I nestled a brush against the side of the ruler and pushed it up against a file I lightly moved flat against the face of the square. I reinstalled the brushes and remeasured the resistance. Still high! Well, there was nothing left to do but clean the slip ring. I soaked a rag in acetone and started the motor. I held the rag against the outer slip ring for as long as I dared and remeasured. 7 Ohms! Then I remembered I had polished the slip rings with Mothers mag wheel polish before I installed the rotor....

    Ford trucks sakes....

    I didn't even have to reach to clean the inner ring, it was now in the high normal spec. I will clean it when I go to install the new brushes and holder.

    So after waiting a few hours for Adolph Coors to wave goodbye, I buttoned the bike up and went for another spin. I now get a solid 14.4V with as little as 3000rpm. I am getting a great charge with as little as 50km/h on the speedo in top gear. This is probably better than this bike has ever charged in the 9 years I have owned it.

    So, to recap:

    Make sure the copper leads on the brushes are not frayed.

    Make sure the brush tabs and wire lugs are clean.

    Make sure there is sufficient contact between the brush end and the slip rings.

    Do not use metal polish to give the slip rings a better surface finish than they need, or at least give them a very thorough cleaning with acetone before installing the rotor. There was no visible contamination on the ring, yet it was way out of spec for resistance. This shows how susceptible to contamination they are.
    Last edited: Jun 30, 2020
    lakeview and Jim like this.
  19. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    This should be in the tech menu or at least linked into an existing thread in there............nice to see the problem solved and the process getting there
    Jim likes this.
  20. 5twins

    5twins XS650 Guru Top Contributor

    I've always used chrome cleaner to clean my slip rings, but I wipe them down afterwards with electrical contact cleaner. I've never had charging issues because of this. Both my bikes charge nicely in the mid 14's once the revs are up. Both put out low 12's at idle, drop to mid 11's when you turn the lights on. Charging rate goes up immediately when revved after starting. No need to wait for it to slowly build.

    However, what I have noticed is a difference in the way the peak output is maintained between the two bikes. My '78 has the aftermarket VR115 automotive regulator installed. It peaks around 14.2 or 14.3 right after starting but eventually drops a few tenths after the battery charge is replenished, after riding a few miles. My '83 with the stock combined reg/rec never drops, it always seems to stay at it's max (around 14.5). I may eventually try a Fiat regulator on the '83 and it will be interesting to see if it's output changes as the battery gets recharged.

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