Author Topic: Mk5 charging  (Read 4942 times)

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Offline dalgrae

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Mk5 charging
« on: 16 Oct 2016 at 12:17 »
I start off my ride as today with a fully charged battery ,the bike started first kick and the 30 mile ride was perfect, on my return I put the battery back on to a maintenance charge which on switching on the charger showed 6.1 volts and only 1 bar of charge and not the usual 6 bars.Fully charged the battery normally reads 6.4 volts.All the bikes electrics seem to show as original except the new battery,with engine running the ammeter does not really move much at all ,when the magneto was completely overhauled a couple of years ago the dynamo was confirmed as charging OK,do I suspect the exiting regulator or can anyone please advise me of any checks I can carry out.If it is the regulator is there a modern type replacement available that is recommended and if so what wiring changes if any are required

Regards. Colin

Offline Hampshirebiker

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Re: Mk5 charging
« Reply #1 on: 16 Oct 2016 at 15:26 »
I've never played with the bike regulator, but mine looks similar to the one on my Triumph 2000 car. I had this problem on the car & fiddled about with the moving parts inside. I probably gave the contacts a squirt of contact cleaner as well. The ameter then showed a healthy charge when I restarted it.
It was a few years ago so I can't remember exactly what I did. Take the cover off & make sure the contacts aren't stuck.  HTH.
Dave.

Offline douglas1947

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Re: Mk5 charging
« Reply #2 on: 16 Oct 2016 at 18:41 »
Colin,

you can check the output of the dynamo /regulator:

start the bike and disconnect the cable to switch (+ or -, depends on your wiring),
connect a voltmeter between this cable dnd frame (earth).
It should show around 7,4volts (to charge the battery), when engine runs around 2000 r/min.

Michael

Offline dalgrae

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Re: Mk5 charging
« Reply #3 on: 17 Oct 2016 at 14:49 »
Hi thanks for the replies I tried out various tests and came to the concluion it is the regulator at fault ,with the bike running and the regulator cover removed by playing with the points it showed charge ,so I cleaned the contacts with 1000 grade wet and dry it showed charge but then discharge ,so I have removed the regulator and will strip out one half of the points and do a proper clean up,if still no good I see that Wassell do an electronic 6 volt positive earth type for about £30

Regards. Colin

Offline eddie

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Re: Mk5 charging
« Reply #4 on: 17 Oct 2016 at 17:08 »
Colin,
          Be careful if you dismantle your voltage regulator. The points gaps and the air gaps at the ends of the coils have to be correctly set for the unit to work properly.
  Before doing anything, check that there is an earth wire from the mag to the earth side of the battery, so that you are not relying on getting a good earth via the crankcases and frame.
  Regards,
               Eddie.

Offline dalgrae

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Re: Mk5 charging
« Reply #5 on: 17 Oct 2016 at 17:37 »
Thanks Eddie I will check this out tommorrow.

Colin

Offline dalgrae

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Re: Mk5 charging
« Reply #6 on: 20 Oct 2016 at 12:39 »
Hi again Eddie , as you suggested I checked for the earth and there were two wires attached to a small boss on the o/s of the magneto so I assume these to be the earth wire you refer to and they were a good connection, I have decided to order a replacement regulator from a supplier I have often used as the existing origing unit must have become unreliable

Regards. Colin

Offline douglas1947

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Re: Mk5 charging
« Reply #7 on: 20 Oct 2016 at 17:54 »
Colin,

did you check the polarity of your dynamo?
Is it a positiv earth?


Michael

Offline eddie

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Re: Mk5 charging
« Reply #8 on: 20 Oct 2016 at 19:44 »
If the dynamo is not giving any charge, the field coils may have lost their residual magnetism. This can be restored by removing the 2 wires from the dynamo, and then connecting the 'F' terminal to the live side of the battery for a couple of seconds (be careful, the wire may get hot!), then connect the original wiring again. The dynamo should now produce a charge of the correct polarity.
  Loss of residual magnetism is often the result of the bike being idle for too long a period.

  Regards,
                Eddie.

Offline dalgrae

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Re: Mk5 charging
« Reply #9 on: 21 Oct 2016 at 07:36 »
Thanks for the advice I did check the dynamo was positive earth ,during my tests with the bike running but not showing any charge on the ammeter and with a volt meter accross the battery it showed just over 6 voltsbut did not change at all when bike revved up ,I removed the spring clip and cover from the regulator and put mild pressure on one of the moveable points spring plate it seemed to make contact and ithe ammeter jumped over to show a charge the voltmeter also showed  it moving to 6.5 volts plus,I took my finger off the points plate and within a couple of seconds it clicked out and the ammeter returned to show no charge,no matter what I did it would only click in by putting finger pressure on the moving plate and then click out,when I had the magneto completely refurbished the same company stripped and checked the dynamo and said it was fine and showing a good output,so from all this I have assumed the regulator has reached the end of its life that is why I have ordered a replacement

Regards. Colin