Electrics- chargiing etc

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

Postby Oggers » Sun May 24, 2020 4:18 pm

As many will have gathered by now, my electrickery skills are not as they ought to be. Confirmation therefore required please.

Firstly. chaincase seal sealed with club seal - so far so good.

Dynamo seal - sealed with a silicone/nitrile O ring and RTV silicone - still one or two drips but nowhere near as bad. I'll see how it goes....Meanwhile, in the course of much faffing about and standing idle no doubt, the dynamo was only giving out 1/2 V. I reflashed it, and eureka! It jumped back into life and seems to put out a healthy votage when connecting the two terminals D & F and measuring the PD across one terminal and Earth. I think all is well here now.

However - and isn't there always a however, in the course of fine tuning my rather fine Altette horn, I drained the battery. It's a cheap Chinese thing. I gave it a charge on the 6V charger and it showed about 2.5V. I replaced it in the hope that the dynamo would do the rest and not wanting to wait to ttake it a ride out, but nothing on the ammeter on he bike. Not charging at all. It did charge on the bike previously when I put it on charge for much longer - when it showed about 5V after a longer charge.

So - the question is, does the battery need a minimum voltage before the dynamo can actually charge it? Thoughts welcome....

I may just buy a replacement anyways- I have had good experience of Motobatt and their MBT6N6 seems to be the job. I have the Exide hard rubber case. Thoughts again welcome. Does anyone here have one installed?

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Re: Electrics- chargiing etc

Postby Mick D » Sun May 24, 2020 4:51 pm

Oggers wrote:So - the question is, does the battery need a minimum voltage before the dynamo can actually charge it? Thoughts welcome....


No - I don't believe so, the danger is that charging a battery from a low state with a dynamo may cause it to charge too quickly and overheat - better to charge it with a dedicated battery charger first.

Oggers wrote:I have had good experience of Motobatt


My 12V Motobatt seems to be dying after two years of very easy life :( :( which is a shame as Iv'e just bought a MBT6N6 for another restoration :roll:

I will be looking elsewhere for my next battery.

Regards Mick

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Re: Electrics- chargiing etc

Postby Oggers » Sun May 24, 2020 6:34 pm

Update on this - I charged the battery up - off the bike - and no joy. Still not charging. Dynamo looks good - still getting about 6V from it on just above tickover, and 9 or so when revved slighly more. I'm thinking regulator, which on mine is a modern version - black box thing. Annoying really, as a few hours ago it was charging. There seems to be circuit of sorts - lights come on when switched, so nothing obvious, to me anyways.....

Anyone any clues about how to test this modern regulator?

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Re: Electrics- chargiing etc

Postby Mick D » Sun May 24, 2020 6:53 pm

Hi

What voltage do you see across the battery? - and then:

What voltage do you see across the battery at tick over?

Regards Mick

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Re: Electrics- chargiing etc

Postby Oggers » Sun May 24, 2020 7:11 pm

Mick

It's about 4.5V when not running. Ithink this is too low. The regulator is one of these small TEB tec things - so I believe the battery needs to be fully charged before charging will occur. I'll charge it (off the bike) overnight and revert.

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Re: Electrics- chargiing etc

Postby Duncan » Sun May 24, 2020 9:10 pm

Some of the modern regulators will not cut in to charge a flat battery, one of the dodges is to start the bike with the battery disconnected and then connect it.

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Re: Electrics- chargiing etc

Postby Oggers » Sun May 24, 2020 9:37 pm

Hi Duncan - That's an interesting tip and thanks. I may try it! I'll give it a charge first. I have been trying to ascertain what the minimum battery voltage requirements are - but no joy. I do seem to remember modern stuff needs pretty much 6 or 12V

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Re: Electrics- chargiing etc

Postby Mick D » Mon May 25, 2020 5:48 am

Are these the specs?

http://www.aoservices.co.uk/data/v-reg.htm

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Re: Electrics- chargiing etc

Postby Groily » Mon May 25, 2020 6:20 am

Hmm. Fully charged a 6v battery should show about six and a half volts. At 4.5v it was still very flat. At 2.5v as before, very very flat. Have to question whether the thing is any good.
Some regulators will work with a flat battery, or no battery at all.
A regulator that wouldn't charge anything except a fully-charged battery would be as much use as a chocolate teapot!

However, in the hope that the reg is meant to work with a flat(ish) or no battery, it is worth putting a meter between the wire that goes to battery live and earth, on the volts scale, with the battery disconnected, to see if anything is coming through. If not, go back to the wire that supplies the ammeter (A from the regulator) and repeat the test. If it works with the ammeter out of circuit, then there's a fault there. If it doesn't work any which way except straight off the dynamo with F&D bridged, per your previous test, time to look at the regulator again I'd say, as well as sorting out a decent battery as you propose doing. (Am assuming electrical polarity is right throughout of course.)

Ref the dynamo, it's worth putting a bulb from D&F to earth with the engine running - a free voltage of 9v might not mean that much. A decent E3L will shove out 20v odd with a few revs, and blow bulbs - but safe to test using a 12v bulb to about 2000rpm engine usually.

Good luck, and I hope the dynamo is OK as you won't want the fun of stopping the oil leaking again any time soon I suspect!

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Re: Electrics- chargiing etc

Postby Oggers » Mon May 25, 2020 8:30 am

Mick

Yes - that looks like the job. I have not removed it from the mount as i still want to try fully charging the battery first. Reading the literature on that website, it does look as if that regulator needs a reasonably well charged battery to allow charging. It worked before I drained the battery testing the horn!

Groily - Yes all good points, but simple stuff first I feel. Battery may well be goosed, but I'll charge it to over 6V and revert.

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