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How do you check if the alternator is functioning properly.

Discussion in 'Parallel Universe' started by EnderTheX, May 8, 2011.

  1. JRWooden

    JRWooden Homeless motorcycle vagabond ... and ... loving it

    Joined:
    Jul 5, 2008
    Oddometer:
    6,423
    Location:
    The great state of confusion
  2. Reaver

    Reaver How Did I Get Here?

    Joined:
    Aug 7, 2008
    Oddometer:
    19,252
    Location:
    Zona Sur Costa Rica
    So, are you sober yet? Now that I'm in a hot zone and my headlight reflectors are going black, I'm looking into Series things. Pics wudya?

    I see you haven't found the Avatar store yet.......
  3. tofire409

    tofire409 Geared up and ready.

    Joined:
    Sep 6, 2009
    Oddometer:
    900
    Location:
    Toronto, CDN
    So sometimes ignorance is bliss...but I had to go and tinker :rolleyes

    Reading at the SAE connector (direct to the battery) 12.58v motor off
    Reading at the SAE connector (direct to the battery) 14.14v at idle

    [​IMG]

    #1-2 stator wire =.4 ohms
    #2-3 stator wire =.5 ohms
    #3-1 stator wire =.5 ohms

    #1 stator wire =28v idle / 70v+ at 4000k+
    #2 stator wire =28v idle / 70v+ at 4000k+
    #3 stator wire =28v idle / 70v+ at 4000k+

    All good so far but I couldn't get my meter to ping on a ground :confused

    [​IMG]

    In fact I got nothing...no measurements at all. Is there a better ground location? Have I done something wrong?

    http://advrider.com/index.php?threads/charging-system-diagnosing-is-it-really-working-right.809879/ is what I followed.

    I'm coming up to a 5000km oil change, perfect time to crack the case if need be...not that I have the parts to do anything about it.
  4. Reaver

    Reaver How Did I Get Here?

    Joined:
    Aug 7, 2008
    Oddometer:
    19,252
    Location:
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    Those pins are supposed to be infinite to ground.


    "Then disconnected measure each wire's resistance to ground (chassis) It should be infinite....ie no reading. If it is not infinite... The wire that is not infinite...indicates a shorted coil, and the stator needs to be replaced. If those test are good...then proceed to test the resistance between each wire.... It should be between 0.5-2 ohms. If it is more... There is an open circuit in the coil that measured more..... and the stator needs to be replaced."
  5. nvklr

    nvklr Been here awhile

    Joined:
    Jul 11, 2008
    Oddometer:
    743
    Location:
    Carson City
    "

    Reading at the SAE connector (direct to the battery) 12.58v motor off
    Reading at the SAE connector (direct to the battery) 14.14v at idle"

    That pretty much shows right there everything is working properly.
  6. tofire409

    tofire409 Geared up and ready.

    Joined:
    Sep 6, 2009
    Oddometer:
    900
    Location:
    Toronto, CDN
    So by not having the continuity ring or anything else would suggest that I'm golden!

    nvklr...that's what I thought, but I wanted to go further just to see.
  7. nvklr

    nvklr Been here awhile

    Joined:
    Jul 11, 2008
    Oddometer:
    743
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    Carson City
    I kinda suspected that. Very cool.
  8. ebrabaek

    ebrabaek Long timer

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    5,699
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    Grand Valley, Colorado
    As Reaver correctly quoted above, those should be infinite. If you measured anything, then that would indicate that the insulation on that leg ( coil) is breaking down. Your readings indicates a good working stator.
  9. tofire409

    tofire409 Geared up and ready.

    Joined:
    Sep 6, 2009
    Oddometer:
    900
    Location:
    Toronto, CDN
    Thanks...I was confusing infinite with having continuity, or the meter ringing.:doh

    Now to get my hands on a Series Rectifier!
  10. GETTHUMPER2

    GETTHUMPER2 Been here awhile

    Joined:
    Feb 1, 2013
    Oddometer:
    559
    Location:
    SOUTHERN CALIFORNIA
    Check with Jack @ Roadstercycle
  11. wipe-out

    wipe-out Been here awhile

    Joined:
    Jan 9, 2012
    Oddometer:
    520
    Location:
    Germany
    Trying to wrap my head around this as I am having issues with my battery. Tried following the instructions in on of the first posts by locating that connector to take the readings. Since my bike was rebuild at some point I'm afraid the wiring is a bit different:

    [​IMG]

    I think I may have found it a little further down, but that is mainly based on the fact that it is the only connector I could locate with three yellow wires running into it. Does that seem right?

    [​IMG]
  12. wipe-out

    wipe-out Been here awhile

    Joined:
    Jan 9, 2012
    Oddometer:
    520
    Location:
    Germany
    Okay, bought a multimeter. Before taking out the battery to get it charged at a local shop (since the bike won't turn over) I took a reading straight from the battery with the following settings (pic not taken during the reading):

    [​IMG]

    Got a little over 11V.

    Should have the battery back in about an hour and will see what I get, especially with the bike (hopefully) running.

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  13. sarathmenon

    sarathmenon Armchair Adventurer

    Joined:
    Mar 29, 2012
    Oddometer:
    1,540
    Location:
    SFO Bay Area
    The Rectifier and stator is on the right side of the bike. The rectifier is the finned part bolted on the right side, slightly lower and toward the front of the panel you opened. The right engine cover houses the stator, and has a black wire coming out of it. If you trace the wire up, you will see that it plugs into a 3 wire lead coming out of the rectifier. If you continue looking, you will see another lead coming out of the rectifier, with 4 pins in it (2 +12VDC and 2 GND). What you want to do is:
    1. Keep the bike turned off
    2. Disconnect the plug from the stator that goes into the rectifier.
    3. Take that multimeter which you haven't bought yet :lol3, turn the knob to resistance check.
    4. Keep measuring the reading between pin 1 and pin 2, pin2 and 3, and between 3 and 1. The actual value varies from bike to bike, but all three readings should all stay the same, or very close to each other.
    5. With the multimeter in the same setting, test between each of these stator pins and somewhere on the frame. This should read inifnity, or some stupid high number in Mohms.
    6. Start the bike, ensure you have some buffer left in the battery for the next start.
    7. Put the multimeter in the V/AC setting. Measure like in step 4. All values should be consistent at the same engine rpm.
    8. If you have an extra pair of hands, rev the engine slightly. The voltage reading should increase linearly based on the rpms.
    If any of these values are off, chances are you have a partially burnt stator.

    Oh, and clean that bike :lol3
  14. wipe-out

    wipe-out Been here awhile

    Joined:
    Jan 9, 2012
    Oddometer:
    520
    Location:
    Germany
    Thanks. Got the battery back, it is charged now and reading 12.9 straight from the terminals. Will put it in next and then read at the terminals with the bike running. From what I understand I should get around 13.8 at idling and then 14.8 as I rev the engine up. If that seems off I'll trace the wires as per your description and try my luck with those readings.

    Re point 2: Does it stay disconnected throughout the whole procedure?
    Re point 3: What's wrong with the one I got (taking aside the fact it's the online I could source)?

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  15. sarathmenon

    sarathmenon Armchair Adventurer

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    Oddometer:
    1,540
    Location:
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    That's correct. There is a newer R/R on the 2011+ US spec bikes that outputs a higher idle voltage, but it's a fairly minor point. If you get 14+ volts when you rev the engine, you are doing fine.

    Yes, it has to be disconnected. The function of the rectifier is to take input AC and convert it to a stable DC 14.4V. If your stator is connected to the R/R, you will notice different readings because the R/R is drawing power. Also, remember to reconnect the stator after taking all the readings :-D
    The one you have is fine. My message was posted before I knew you had one.
  16. wipe-out

    wipe-out Been here awhile

    Joined:
    Jan 9, 2012
    Oddometer:
    520
    Location:
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    So I get the following readings (from the terminal), I'm afraid no good.

    12.8V with ignition turned off
    12.65V with ignition on
    12.45V when idling
    max 12.7 when revving

    What does that leave me with? New alternator (or try and find someone that can rewire the old one)?

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  17. sarathmenon

    sarathmenon Armchair Adventurer

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    Mar 29, 2012
    Oddometer:
    1,540
    Location:
    SFO Bay Area
    Start with the troubleshooting steps I mentioned earlier - the same details as in Erling's pictorial. You need to isolate whether the stator is dead (very very common if you read the past posts) or whether you have problems upstream of the stator. My money is on the stator. You have the multimeter, and it's a 10 minute process, and based on your readings, I have a feeling you aren't doing much riding today.

    If you determine that the stator is the problem, open that case and inspect the stator. It's again a 10 minute process (plus a gasket if you are ham-fisted). If you lay the bike down before you start, you won't lose any oil. Mexico seems like the place where you will find shade tree mechanics willing to rewind the stator. If not, I think electroport gets the recommendation here.

    This is also a good time for a plug for the permanent fixes: A series R/R eliminates the early death of the stator. A voltmeter on your dash will also detect this problem in time before you kill a battery. And if you are feeling very reach, BMW has a 1000 dollar flywheel for you.
  18. wipe-out

    wipe-out Been here awhile

    Joined:
    Jan 9, 2012
    Oddometer:
    520
    Location:
    Germany
    There. You have me take my bike apart. :-D Never done any of this before but here we go.

    With the resistance reading I get a constant 1.5/1.6 value for all three. Of the frame it is inconsistent and also kinda jumping from one value to another.

    No on voltage, same settings as above (knob turned to 20) I get - nothing (but consistent nothing on all three). Doesn't change when revving. Could I be doing something wrong? Or does it just mean it is gone for good?

    I'm reluctant to take off the engine cover without anyone nearby that knows what he's doing. If I f**k up the gasket for whatever reason I'll be in more trouble than before?

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  19. sarathmenon

    sarathmenon Armchair Adventurer

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    Oddometer:
    1,540
    Location:
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    Did you set to V AC? Looking at the picture of the voltmeter you bought, it's the top setting, right of OFF called V~. 200 is a fine band, it doesn't go above that.
  20. wipe-out

    wipe-out Been here awhile

    Joined:
    Jan 9, 2012
    Oddometer:
    520
    Location:
    Germany
    Nope, hat it set to the top lefthand setting, I guess DC then. When I set it to the setting you suggest I get 27V straight off the battery and that didn't make sense to me?

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