Charging problems -R100RS

Discussion in 'Airheads' started by ashrubbery, Jun 3, 2010.

  1. boxerboy81

    boxerboy81 Stay Horizontal

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    Has the spring at the new brush been wound on adequately? If not, the brush won't contact the rotor properly.
    #21
  2. ashrubbery

    ashrubbery Adventurer

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    yes the spring is fine. We even used a small screwdriver to make sure the brushes were making contact but it still was not charging properly.

    Anyways, ive a trip to go on and shouldve left today. Its probably something stupidly simple but since I dont have the time to fiddle for weeks, Ive decided to spend some money and take into a motorcycle electrical expert tomorrow. That should sort it out.

    Will tell you what he finds.
    #22
  3. bushyb

    bushyb Adventurer

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    So what was the problem at the end of the day?
    #23
  4. ashrubbery

    ashrubbery Adventurer

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    Sorry for such a late response. This problem actually took two years to get mostly sorted.

    What I did from June 2010 to the present.

    -Got the diode box completely checked and re-soldered by a motorcycle electrical business. (didnt help)

    -Brushes rechecked. (didnt help)

    -Wiring checked, changed some connections to brass if i can remember correctly?

    -Changed brake light to a smaller globe

    -Initially changed regulator to a car regulator, then it was found that this wasnt working (faulty?) changed to BMW regulator this was found to be faulty (really?), then changed to another car regulator (cant remember what type but can check if someone is interested). This seemed to do it, the bike charges much better now.

    -Replaced motorcycle battery with a full sized car battery (again i forget which type, but can check). The battery takes up all the space underneath the seat (no space for the little compartment thing that goes there).

    -Fixed starter motor (bike does not struggle to start now, usually starts with one or two flicks unlike before. Means it drains the battery less at each start up).

    Now im not convinced the bike is charging 100% of what it should, because the Generator light can still be seen dimly in the dark indicating a minor problem, but the bike works fine for me. It charges well in the day, charges at night with the lights on, and has no problem with doing lots of short trips in traffic (~5km).

    The three main things that helped for me where
    1) A regulator that seems to work properly
    2) A larger battery
    3) A fixed starter motor

    Cheers,
    #24
  5. ignatz72

    ignatz72 call me iggy

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    You still haven't mentioned testing or replacing the rotor. This very well could be a rotor issue.

    Also, you did some work with the brushes, but did you de-burnish the slip rings with emory cloth or fine sandpaper?

    Have you given thought to buying Rick Jones' book? If you had this book your problem would likely be solved by now. Apparently he offers an electronic version now...
    #25
  6. supershaft

    supershaft because I can

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    Replace the battery? Go to Radio Shack and get a cheap multimeter. Check batt voltage at the battery. Hit the starter. If the batt voltage drops very much below ten volts THEN you need a new battery. Static battery voltage is almost a useless test. Most bad batteries will charge up to 13 volts but can't deal with any load. More expensive multimeters have an amp gauge but in a lot of cases a test light will do the job of an amp meter. That or a voltage drop test which in many ways is the same thing as a amp draw test.

    Check and clean your connectors? Don't forget to check the wires too! Worn insulation. Just that tiny nick right were it happens to be rubbing on something? If it's a hot wire that IS at least part of the trouble. Are the wires hard right by the connectors for an inch or two or even further up the wire? The wire has been over loaded and needs replacing. Wires that have been too hot don't carry an electrical load like they should. Your bike has a few electrical wires that get over heated regularly. Namely the B+and auxiliary diode board ground wires. Typically, they need replaced every 25K to 50k miles if you want to maintain optimum charging.

    Static testing rotors? If it tested open it's open but they are very often bad and still test good. How? The centrifugal force of spinning moves things! A good connection can open up when it is spinning or some of the wires can rub together and cause a coil to coil short thusly taking part of the winding out of the equation. Some people advise that if the charge light is coming on it can't be the rotor. Wrong!

    Brushes usually last well over 100,000 miles from what I have seen. I have never seen a rotor's slip rings that need cleaning if the brushes were good. I guess if it sat for a long time or was hardly ever ridden?

    Good luck!
    #26
  7. BMW Fanatic

    BMW Fanatic n00b

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    Hi, I run a 1978 R100S, a 1983 K100RS and am building a R100GS twinshock. I'm a retired mech and elec eng and make parts such as diode plates, voltage regulators, ignition systems and mechanical parts. My R100S charges through my diode plate and I use the car type voltage regulators and modify the slip ring brush holder to suit. Folks have told you to replace the battery, quite right, that's the starting point. Do you have the old mechanical regulator or the newer electronic one ? Either way, put a voltmeter between the battery positive and the blue wire on the regulator which is the +13.5V output of the diode plate to the regulator. The charge light is connected between this wire and the battery positive when the ignition is on and so the light goes off when its charging because there is ( almost ) no voltage between them. If everything's OK the voltmeter will show about 0.1 to 0.3 volts with the blue wire positive. This is so for ALL alternators. If you don't get this voltage but get a voltage with the blue negative then check the diodes on the diode plate ( for conducting one way, blocking the other ) and the rotor ( for being open circuit, I've popped many rotors over the years, Guzzis do the same ). If you have a popped diode, generally the charge light goes dim, in daylight you can hardly see it. At this point, I need some more feedback from you to continue.

    I also need something. There's an Italian chap on this forum who built a Twinshock GS from an R65, EXACTLY what I'm doing. I need his contact details to find out what rear shocks he used from the swing arm / bevel drive to the main frame. Thanx.
    #27
  8. ashrubbery

    ashrubbery Adventurer

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    Hey!
    So Im back with another issue :D
    After my last post I must admit I havent really touched my bikes electrics. Im sure my bikes charging is not perfect but it has pretty much worked for my needs and thats fine by me.

    Now something else has happened that I have not seen before. On a trip this past week, about a 150 km journey in the dark (had the headlight on), and wet, i noticed from my voltmeter that my bike wasnt charging. But the weird thing was my GEN light hadn't gone on. WEIRD i thought!

    So i took the cover off and checked the wiring, everything seems to be in place, brushes look good, they are making contact even at high revs. I have enough info from this post alone and from the rest of Airheads to know how to check the alternator, diode box, regulator, battery to see if any of those are faulty. I havent done this yet, decided to do it later, but thought I may as well replace that bum GEN light bulb. Put a new light in (checked it with the voltmeter, it checked out). The GEN light is still OUT when NOT charging.

    So after reading through the forum am I correct to say that the bike will NOT charge if the bulb is not working properly????
    Also, someone said that it must be replaced with a BMW light. Seriously?

    Anyone have any info on the GEN light issue?

    Cheers,
    #28
  9. Warin

    Warin Retired

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    The problem is you have no idea of what you are doing! Or how the alternator system works!

    ------------------------------
    I would assume that the GEN light does not come on when you first switch the bike on (motor not running)? The FIRST thing I would do is remove the front cover and put a short across the rotor slip rings (what the brushes connect to). If the GEN light now comes on (ignition switched on) then the rotor is open circuit and faulty. This is a common failure! Well known. Regular problem. :deal

    ---------------------
    In the long term READ all of http://www.batteryfaq.org/

    In particular http://jgdarden.com/batteryfaq/carfaq5.htm

    -----------------------
    Understand that the bike (car/truck/bus) electrical system does NOT run off the battery when the motor is running! It 'runs' off the alternator!!! A larger battery does NOT help the running condition of the electrical system.

    =======================
    Anyone who tells you you need a BMW light for the GEN light should not be seen again, unhelpful bastard is the term to be used. While it may have been said in jest for the beginner it is not funny. Ostracize them.
    #29
  10. Plaka

    Plaka Brevis illi vita est

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    Gotta have the bulb, it's gotta be good and more or less the correct resistance. Mottorad Electric has an inexpensive kit that puts a resistor in parallel with the bulb to keep the circuit going if the bulb burns out. Cheap CYA.

    The gen light should come on with the key on and the bike not running. If this is not happening, fix it.

    I don't know the circuit. All I've ever had is open rotors. Get the charging system book from Mottorad Electric too. I don't have it but If I know Rick it will be money well spent. Next time I have some cash I'm getting it just to add to the library.

    I would scour Snowbums site on this topic too.
    #30
  11. Warin

    Warin Retired

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    And your tell someone else how to fault find it?

    This circuit is used on MOST cars, trucks, buses, farm tractors, bmw motor cycles, motoguzzie motor cycles, tractors ... anything that uses an alternator to charge a battery! It is common. And I can draw it from memory. Much easier then the block diagram of a TV!
    #31
  12. Plaka

    Plaka Brevis illi vita est

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    So quit with the drama, draw it and post it.

    Put up or shut up, k?
    #32
  13. Warin

    Warin Retired

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    :freaky Yep Yep .. put the link up for the battery FAQ and the more specific link for the alternator bit .. should have reput it up on my 'rant' .. Just surprised at the offered help with the lesser knowledge? Something like that ..

    Again http://jgdarden.com/batteryfaq/carfaq5.htm

    That has a diagram of the alternator, output graph, a description etc etc .. not retyping it here when someone else has already done a reasonable job elsewhere. I'd do the diagram differently .... but it would only be minor tweeks.
    #33
  14. boxerboy81

    boxerboy81 Stay Horizontal

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    I don't think the book has been available for a while? has he reprinted another run?

    For me, if the ignition is on, but the GEN is off before the bike is started, it's been the rotor. Twice. Common problem.
    #34
  15. ashrubbery

    ashrubbery Adventurer

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    Thanks everyone for your responses, much appreciated!
    I have confirmed that it is indeed the rotor.

    Ive heard these may be able to get rewound?
    #35
  16. Darryl's bmw

    Darryl's bmw Darby

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    Yes it can be rewound, but it is a pain to do.

    I have one that was wound in the opposite direction with slightly bigger wire. In theory the spinning wires will tend to close rather than open.
    #36
  17. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    New rotors can be had for $90. I can't a imagine you'd find anyone willing to endure the frustration of rewinding one of those for much less than $90.
    #37
  18. Plaka

    Plaka Brevis illi vita est

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    They go open where the wires aren't potted inside the fiberglass tubes. Vibration gets to them. if you inject epoxy into the tubes they are more robust. if you change the wire diameter you also change the amount of field the thing can generate and hence it's output. This is why there isn't a single HUGE wire in there. it's the number of turns that count and there is only so much room.



    Mottorad Electric sells rebuilds on an exchange basis. I imagine most electric motor shops could do it too but I'd go with someone who has a lot of experience with that exact part and it's specs. The price is decent too.
    #38
  19. boxerboy81

    boxerboy81 Stay Horizontal

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    #39
  20. Warin

    Warin Retired

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    to the slip ring? I would think. The slip ring being a fixed point, the winding being another and the flex takes place in the crossing. You can also add the heat stress of the soldering at this point.

    ---------------
    There should be little influence of the winding direction - the main force is centrifugal. Changes in speed in one direction would have foces associated with winding direction, but speed changes happen in both directions. So teh direction of the winding won't matter much.
    #40