Author Topic: Dragonfly not charging  (Read 611 times)

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Offline mikkings2

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Dragonfly not charging
« on: 20 May 2022 at 17:06 »
Gents,
          Bike off the road for a month, flat battery which wouldnt recover, new AGM fitted, fully charged 12.89v, running engine not showing charge on the ammeter, battery at 12.3v with very slight increase with revs (0.2v), disconnect one side on the battery and showing 1.5v leakage, bike is 12v +eth with green and yellow commoned, can just see what looks like a reg/rec under the tank so this is the first port of call. Would also like to check the alternator, DRG 2133 shows coils 6 oclock and 8 oclock commoned on Yellow and the other 4 coils on Green, I can check continuity and earthing but anyone know the nominal resistance of them?
Thanks Mike

Offline eddie

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Re: Dragonfly not charging
« Reply #1 on: 20 May 2022 at 18:30 »
Hi Mike,
             I had similar problems with a Miller generator that I fitted to a Douglas special that was running on 12 volts. Having carefully cleaned the stator, I checked each coil for continuity and leakage to earth - continuity good and no leakage! On starting the engine, I got a good charge which gradually dropped off to zero. A second check showed a bad leakage to earth. A second clean and blow out with an airline cured the leakage, but starting the engine again gave the same result. After a lot of head scratching, I came to the conclusion that the engine the generator came from had probably suffered considerable wear resulting in iron particles being collected by the magnetic field in the generator coils - which eventually aligned and caused the short. I resorted to carefully dismantling the stator, unwinding one of the coils to check for the number of turns and guage of wire (20g). From a now not so reliable memory, I think there was about 230 turns in each coil. Anyway, I ended up winding 6 new coils (with everything encapsulated in resin). The rebuilt stator now happily gives an 8 amp charge (96 watt output from a generator that was originally rated at 60 watt!). During the build of the bike, I ditched the original rectifier and fitted a 15 amp solid state unit. The original units dont stand the test of time, and often consume more power than they pass.

  Hope some of this helps,
                                      Regards,
                                                   Eddie.

Offline mikkings2

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Re: Dragonfly not charging
« Reply #2 on: 21 May 2022 at 14:58 »
Thanks Eddie,
                   Checked battery this morning and no leakage voltage so reconnected battery, turn on and meter flicks to discharge and returns to centre i.e. no ignition. Confirmed with voltmeter across battery terminals seeing load on/off. This is really puzzling as the only thing I have done is disconnect the battery +ve terminal to check for leakage, it has a Boyer Micro MKIV system fitted by a previous owner and has given no issues, started first kick yesterday. Looks like I'll need to strip down and do some more testing. Thoughts?
Thanks Mike

Offline eddie

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Re: Dragonfly not charging
« Reply #3 on: 21 May 2022 at 16:02 »
The best thing to do with a Boyer is see how far you can throw it. I've had 2 bikes with Boyer ignition - they both would pack up without warning - going back to a standard coil and points restored the reliability!

  Eddie.

Offline mikkings2

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Re: Dragonfly not charging
« Reply #4 on: 22 May 2022 at 14:35 »
Thanks Eddie,
                     Still cannot see what I could have done to cause it to fail, pulled the bike apart yesterday, spent much time tracing the wiring to build up a diagram, tested the stator tested fine so hopefully good, have spare reg/rec which I believe work when I get it running again. Re the ignition then the initial kick on the ammeter may be it producing a spark on power up as per their fault finding web page although this the MKIII version. I'm going to give their help line a ring, if no good I may well take your advice about points.
Mike

Offline mikkings2

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Re: Dragonfly not charging
« Reply #5 on: 13 Sep 2022 at 16:11 »
Gents,
            Ignition sorted and bike running after renewing wiring (must have disturbed a poor connection) , alternator knackered just 4.6v o/p,  may as well replace with new, can anyone recommend suitable Lucas to fit, RM20/21 combination? Any advice welcome.
Thanks Mike

Offline eddie

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Re: Dragonfly not charging
« Reply #6 on: 13 Sep 2022 at 16:24 »
Mike,
         A Lucas alternator wil fit - just! They are wider than the Miller unit, so you have to be careful that they do not come in contact with the timing gears, etc. If you decide to fit a repro unit, you may have to fit the matching rotor - some repro units have a 75mm dia rotor, whereas the Miller rotor was 3" (76.2mm).

  Eddie.

Offline mikkings2

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Re: Dragonfly not charging
« Reply #7 on: 14 Sep 2022 at 16:21 »
Thanks Eddie,
                   Pulled it apart today, no gaskets just lots of silicon, hopefully the club do them otherwise I'll make them. Should give me a little more clearance when fitted, there only problem I forsee is centring the rotor, maybe a run and strip again to check if it's touching?
Mike

 

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