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Alternator Testing

Discussion in 'Technical Help' started by slumdog, Jul 13, 2016.

  1. Out today on 05 999 noticed volts below 12 . Slowly went down to 11.6 blinking. At high reves will get to 12v. disconnected the front bulb bump started, got home.
    Yesterday was at 14v plus so normal. Any idea what could have happened so quickly ?
     
  2. One or more coils on the alternator have started shorting. Fairly easy to test with a resistance meter at the socket between the alternator windings and the rest of the bike. Search on here for instructions.
     
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  3. My first thought would be the start of a failing reg/rec.
    Steve
     
    • Agree Agree x 2
  4. Id go for reg/rec too.
     
  5. Reg/rev for me as well. It's a known weak point and I've had to replace it on my M600.

    Electrexworld do a better and slightly cheaper replacement, although it may be worth checking the price of a genuine original. When I replaced mine a genuine one was only about £30 more expensive, had the right connectors to plug straight in and had lasted more than 10 years and 25k miles up to that point anyway.
     
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  6. Could be or the reg/rec I suppose, as its a known weak point that has a hard life. As I see it the best way is to test the components to see what is working in order to rule stuff out

    I don't know the 999 but I'm going to guess that it's a 3 phase permanent magnet alternator. An easy way to test the whole assembly is to get the output wires from the alternator, usually 3 thick yellow wires, fully charge the battery out the bike and then place it back in and disconnect these 3 yellow wires. Get a multimeter put it to AC around 100V range greater than 80 anyway, and test the 3 yellow wires 1-2, 1-3, 2-3, at a about 2k and I'm making an educated guess here around 30-40VAC at say 3-4k around 60-70VAC. Check the manual it may give you figures for testing, also when doing this the bike will obviously not be charging. All 3 wire tests should give approx the same results, any one being significantly different means a stator coil has failed.

    The reg/rec can also be checked if you have a diode function on the multimeter.



    The problem comes if its intermittent, stators can fail hot then go good cold, but if that's the case it won't stay that way for too long

    Just how I'd start to do it

    Depending on alternator type the common replacement recommended for a lot of the bikes on here is the Shindengen MOSFET, RR

    TRIUMPH / DUCATI UPGRADED REGULATOR KIT INCLUDING WIRING MOSFET FH012 R1 TYPE | eBay

    If @Denzil the Ducati comes on and rubbishes everything I've said ignore me and listen to him he is probably "The" acknowledged GNU on electrics for Ducatis

    John
     
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  7. Tested the stators three wires and and two shorted to earth ! :grin:
     
  8. I thank you! (bows...)
     
    • Funny Funny x 2
  9. Just removed the stator and looks black and burnt on one coil - will send off for rewinding - thanks for the help !
     
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  10. Here is the thing

    IMG_1637.jpg
     
  11. Great you got a result & resolved it

    Hat's off to @razz
     
  12. Mmmm,Id go for the alternator.
     
    • Agree Agree x 1
  13. Now you have to try to find why the coils have been overloaded so much. Have you checked your reg/rec connections (yellow wire's plug) for burning/overheating on the pins or at the other end, also look for any scorching on the loom or reg/rec? You can get new stators from Electrexworld iirc (if you have problems getting that one repaired) but compare prices with new oem first. Once your generator is working test your AC output voltages again and see what sort of voltage you are getting on the battery posts with it all running and the wiring back in place. Hate to say it but it is likely your reg/rec is fecked as well
    John is on the money
    Here is a good way to check things are working ok
    http://www.electrexworld.co.uk/acatalog/Troubleshooting-3P-PMG-&-RR.pdf
     
  14. Thanks 'Denzil' for this, much appreciated..One thing I can say , looking back, this might have been a long term degradation as the output showing on the dash has always been on the low side, flashing 12v or no volts showing on tickover. Have sent it to 'Elliotts Motorcycles' Swindon, 100 quid rewind. Now have a multimeter with the diode setting so will check that now ..
     
  15. Slumdog, Elliotts are not far from me. When your system is working properly and all assembled the dash should indicate 14-14.5v with the engine running and a good battery, expect 0.2-0.3v drop when the headlight is switched on at tick over or 14.2v for normal driving most of the time. Anything less than 13.5v with the engine running would have me investigating. Also try to avoid using the dash as a direct indication of the battery voltage, its great for checking the health of the generator system with the engine running but not so good for checking battery voltage before start up. Just switching the ignition on takes quite a bit of current which depends on all sorts of things like connection and earth cleanliness and even fuel pump back pressure due to dirt in the filter, then there are temperature voltage variations on top.

    For interest a new generator from Electrex is £114 inc vat.
     
  16. Have looked on their site and is it the G999 115 dia 54 inner and 15 through the hole ?
     
  17. All together and a new stator from Electrex . Reads on the dash 13.9 at tickover and at all rev. Battery is 13.3 v cold. By the way, 'Elliotts' were too slow in a rewind , more than the promised five days, Electrex sent it straight away and received it following day !
     
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  18. I was going to say stator! We had the same on a 748, was 12v at idle then as soon as u Rev it the voltage just dropped away, was a screwed alternator that because left took the Reg Rec with it!


    Sent from my iPhone using Tapatalk
     
  19. Slumdog, did you get a chance to inspect the reg/rec connections?
     
  20. Guess what the stator has failed again! Have checked the output and its zero. All connections are fine as is the regulator.. Three years old and use is infrequent... What could be burning out the coils ?
     
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