Electrics- chargiing etc

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Re: Electrics- chargiing etc

Postby Oggers » Mon May 25, 2020 4:35 pm

The saga continues.....

Battery fully charged as I can get it - to around 6.3V and fairly stable. Connected everything up again - still no charging looking at the ammeter. Drat and double drat.

Tried Groily's checks - battery off, bike on tickover, voltage between live wire and earth is about 0.3V, same with A (brown) wire to ammeter from reg. There is something there it seems.

So - I am assuming reg works as there is something there and the dynamo is not providing enough charge - despite my bridging wire telling me otherwise. I then repolarized it again, and opened out the ferrules on the green and yellow terninal wires to get a better fit as they have beeen subject to much pulling about, took another reading as above and got around 1.0V on both tests.

Therefore - I think it is dyanamo ....somewhere!

My next plan of attack is to repolorize again - holding the negative to the F terminal for a wee bit longer, and for several times to make certain, and thoroughly clean out the terminals.

Any other advice most welcome as always.

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Re: Electrics- chargiing etc

Postby Oggers » Mon May 25, 2020 6:59 pm

and update to my update.....

Terminals cleaned, repolarized, did a load test on the dynamo with a lamp as per Lucas instructions - all good. 12V Lamp glows brighter when revved. Checked all continuity, checked all earths, checked it all again - still only 1 volt or so across earth and live, and same across earth and ammeter wire from regulator. I'm starting to change my mind and think regulator - which is a real pain as I don't think you can check those easily. However, Alan Osborne is a useful chap, so perhaps over to him?

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Re: Electrics- chargiing etc

Postby SPRIDDLER » Mon May 25, 2020 8:54 pm

Oggers wrote:and update to my update.....

Terminals cleaned, repolarized, did a load test on the dynamo with a lamp as per Lucas instructions - all good. 12V Lamp glows brighter when revved. Checked all continuity, checked all earths, checked it all again - still only 1 volt or so across earth and live, and same across earth and ammeter wire from regulator. I'm starting to change my mind and think regulator - which is a real pain as I don't think you can check those easily. However, Alan Osborne is a useful chap, so perhaps over to him?

Difficult to tell what you mean exactly by 'glows brighter' but with that D to F bridge check the dynamo output is (obviously) unregulated and a 12v lamp should light very brightly (blow even) as with sufficient revs the voltage would rise to 20+ volts. Ideally when doing that check it's a good idea to connect the voltmeter in series with the lamp to see what voltage is there under load. (You have got four hands haven't you? ;) ).
Are the dynamo brushes clean and free to move in their holders and making good contact with the commutator? Is the commutator clean and shiny?
I had an AO regulator and it needed a good blip on the throttle to 'wake it up' and start charging every time the revs dropped, say after pulling away after waiting with lights on at tickover at traffic lights.
I poke badgers with spoons.....from 2 metres.

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Re: Electrics- chargiing etc

Postby Oggers » Tue May 26, 2020 8:33 am

Glows brighter meant it glowed far more than it would have done with 12V across it. I was very wary of increasing revs further as I did not want to damage other electrical bits within the dynamo with the bridge installed. Brushes were cleaned, as was the commutator, all connections checked. I think have excluded the dyanamo being the culprit. It seems to kick out a healthy charge when disconnected, and it is a fairly numb thing - it will either work or it won't.

I appreciate the point about the regulator "waking up" but as aforesaid, there appears to be little coming from it even at moderate revs. Volatge across the ammeter wire for the regulator and earth was no more than 1 volt or so which is clearly inadequate.

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Re: Electrics- chargiing etc

Postby Groily » Tue May 26, 2020 9:00 am

They do sometimes need a real 'handful' to kick in, but you have had the dynamo working strongly and therefore there should be sufficient residual magnetism in the field - so it should be kicking in at sensible revs if the reg works.
I think you are spot on in suspecting that is where the problem is.
Ideally, you want to see 7v in round numbers from the reg A lead, or across the battery terminals, at anything over 1750-2000 rpm, by when it should be regulating properly. Digital meters can be very 'spikey' - but they usually give a decent indication! And there's the ammeter, of course.

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Re: Electrics- chargiing etc

Postby MalcW » Wed May 27, 2020 8:00 am

My dynamo twin had some unlabelled solid state regulator fitted when I first had the bike. It would hardly ever charge, but then occasionally on a long run it would suddenly burst into life and work for the rest of the trip. Weirdly, it would continue to work for the next few days as long as the bike was used, but a break of a few days would send it back to non charging mode. I did the same as you, cleaning and flashing he dynamo, checking connectors etc. In the end I replaced the regulator with a DVR2. Instant success. I have even (ahem) checking its stated ability to withstand reverse polarity connection. Well, it was getting late...

I think your suspicions about the regulator are probably correct.

Malc

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Re: Electrics- chargiing etc

Postby Oggers » Wed May 27, 2020 9:03 am

Gents

With the grateful assistance and clarity offered by Alan Osborne ( AO regulators - very helpful, highly recommended) - I think I have cracked this. Bike now appears to charge, ammeter swings to right with no load, lights remain bright when on, 7V across battery when just above tickover.

My omission was to check the operation of everything with a fully charged battery wired in. It seems of little use in just checking the feed wires - from the reg or the live to the battery across the earth with no battery wired in. My regulator at least needs the battery to push out the necessary volts/amps in order to charge it. It also needs a fully charged battery. I did manage to anticipate the dynamo needed repolarizing though! Lessons learned all round.

I can now return to my favourite dynsamo oil seal leak - still dripping but not too bad, and must now also attend to a broken soldered joint inside the horn. I live in hope that one day I shall spend more time riding it than fixing it.

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