Charging problems

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Charging problems

Postby MalcW » Mon Apr 16, 2018 11:31 am

So, I now have my Model 31 back on the road, but it has become apparent that it isn't charging. The problem may be the dynamo, I haven't had a chance to test the output and if necessary flash it yet. But it may also be the fact that it is running 12v; the voltage regulator is an anonymous aluminium box of indeterminate age with absolutely no markings on it whatsoever. Does anyone else have a dynamo/12v setup that can recommend a regulator? I would like to change it even it turns out that the problem is the dynamo.

Cheers,

Malcolm

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Re: Charging problems

Postby SPRIDDLER » Mon Apr 16, 2018 11:36 am

Malc
This is generally reckoned to be the best one.

http://dynamoregulators.com/dvr2.php
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Re: Charging problems

Postby bitza » Mon Apr 16, 2018 12:52 pm

I would go for D V R 2 same as spriddler neat small encapsulated unit with easy to follow info.

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Re: Charging problems

Postby Groily » Mon Apr 16, 2018 2:07 pm

Anonymous ali box of indeterminate age could be anything! But what wires does it have off it, and what colours? I ask because IF by chance it is a JG voltage regulator (which fits the description if the box isn't ribbed, just plain alloy), the dynamo wiring would need to be changed for it to work. If it hadn't been, it wouldn't; if it has been and now you want to change for another make of regulator, you'll need to check the wiring under the dynamo end cover.

For, say, a DVR2 or an old Lucas regulator, or a V Reg 2 from Alan Osborne, you want one of the field coil wires that poke through from inside the dynamo to go to the F terminal of the dynamo, and the other one to the earth screw that also attaches the wire off one brush. The other brush should go to D terminal. IF it's a JG unit (or maybe some other indeterminate thingummyjig), then the field coil wires should have been connected between F and D on the dynamo, with one brush wire to the earth screw on its ownio, and the other brush to D (along with the field coil wire mentioned).

Have to bear in mind too that which way round you connect the field coil wires determines in which direction of rotation the dynamo will generate. If they have been reversed, or get scrambled while playing, the thing won't generate until they're sorted. Because they're usually the same colour, it can be a pain - anonymous little black wires of indeterminate age would apply to them too! If the thing worked and now doesn't, it was right at some point. If it never worked, could be because it was hooked up all wrong. Or the dyn is dead, or the indeterminate box has lost its determinate function. Oh, the joy of it!

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Re: Charging problems

Postby MalcW » Mon Apr 16, 2018 2:53 pm

Spriddler and Bitza, thank you for the recommendation.

Groily, a bit of Googling suggests that it isn't a JG unit, as they all seem to have 3 wires, whereas this one has 5. Also, the JG images I've seen show 2 mounting studs, whereas this one has 1.

As for whether it used to work, I have no idea. I bought the bike as needing 'a bit of fettling' back at the start of November. 'Fettling' is obviously a word open to interpretation. But it does have an MOT until June, so it was presumably working at some time within the last year. There again, with a magneto and a charged battery at MOT time, who knows? The original 12v battery on the bike was very small, with spade connectors, so I guess wasn't called upon to do much. It looked more like something to power an old transistor radio. And once charged, or rather not, it proved to be distinctly knackered.

I'll get a new regulator anyway, so that whatever happens dynamo-wise I will at least have a unit that I can be confident in, and understand the wiring. I don't intend to do much night riding, but I would like to fit (with apologies to any purists), indicators.

Cheers,

Malc

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Re: Charging problems

Postby g5wqian » Tue Apr 17, 2018 5:41 am

hi Malcom ;
before you start looking at the regulator etc i would pull the dynamo end cap off and shine a torch down inside and see if there is any oil in there .

on my twin [6v system] i had oil inside the dynamo which was causing it not to work , the oil getting in from the timing case side .

i stripped the dynamo down and cleaned it with brake cleaner and blew it out with compressed air , at same time i put new bearings in and a new seal and new brushes , not a hard job for me but fidlly when it comes to the bearing removal etc although you can get at what you need to clean it without stripping it completely .

if the oil has got on the brushes it wont charge , you might get away with a can of brake cleaner and airline to clean it out whilst on engine but the dynamo comes out easily from the engine , just need to be carefull of the drawbolt on the timing case and not doing it up too tight .
a guy previously told me to push the dynamo back in with a lump of wood and tighten the band up and then nip the drawbolt up .

since rebuilding my dynamo , when engine is running it does need to rev past say 1200rpm in order for it to "energise" and start charging and then it will go around half scale on the ammeter when engine is running at steady revs .
the handbook tells you what voltages you should expect to see etc and what resistance from various parts of it you will see but for the troubleshooting side of things i would check for oil deposited in the dynamo before you think it has failed somewhere else and buy a load of parts for it or send it off for repair if you dont want to touch it yourself , could save you a lot of time and expense doing a quick check inside dynamo first .

you probably wont need to flash the polarity , i would check if you have a fuse in line though and see if thats ok as well .

the brushes are easy enough to change but when you run the engine for first time it may need some revs for a few seconds before it kicks in and the brushes are functioning , mine revved up to about 1700rpm and then the meter showed charging .

i did have an intermittent ammeter problem as well at one point , i swapped meters but the new one was wired opposite way round and showed a discharge at first , but simple to swap wires over on its terminals to correct that .

hope you get it sorted easily .
ian .

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Re: Charging problems

Postby MalcW » Tue Apr 17, 2018 8:34 am

Hi Ian

Thank you for that advice. I did some further tests yesterday evening. I checked output at tickover with a digital multimeter and saw nothing. But I think that was my error, as when I gave it some revs with the headlight on the ammeter showed a discharge for a while, then went into a bit of a frenzy, and finally showed a slight charge, but at quite high revs. There was indeed some oil in the end cap, so that will be my next job. One side benefit of doing all of that was that I got to do a bit of fine adjustment of the pilot air screw on my new Monobloc while I was at it. It'll probably never start again...

Cheers,

Malc

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Re: Charging problems

Postby SPRIDDLER » Tue Apr 17, 2018 8:53 am

Malc. A multimeter doesn't really give you a realistic check on the dynamo's health as it really needs a load. I use a crude lash-up with a bulb as the load:

CIMG0015 (640x480).jpg


CIMG0010 (720x540).jpg


When using this the dynamo output is unregulated and will 'run away' up to perhaps 25 volts and blow the bulb if you increase the revs too far.

There's a really good guide to testing dynamos (and other stuff). See in particular paragraph 10 here:

https://matchlessclueless.com/electrica ... as-dynamo/
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Re: Charging problems

Postby MalcW » Tue Apr 17, 2018 9:40 am

Hi Spriddler

Thank you for that information, and the photographs. T'other half is working tomorrow evening, so I think a bit of soldering to make up a test harness is in order.

So is that why when riding normally with no lights there is no charge showing on the ammeter - there's no load on the system? You can tell I come from an alternator background...

Cheers,

Malcolm

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Re: Charging problems

Postby SPRIDDLER » Tue Apr 17, 2018 10:04 am

MalcW wrote:So is that why when riding normally with no lights there is no charge showing on the ammeter - there's no load on the system?

Yes, exactly that. At tickover with the lights on the battery will be drained (and the ammeter will show a discharge) as the dynamo's output isn't sufficient to meet the load of the lights. As the revs increase the dynamo's output will increase until it matches the load of the lights and the battery is no longer being drained. A charge may show on the ammeter for a while until the power that was drained from the battery by the lights has been replaced by the dynamo, after which the ammeter will return to zero. It's generally recognised that one needs to be doing around 35 to 40mph with the lights on in order that the dynamo output will balance the load of the lights. If you do a lot of night riding LED lamps will require far less current (and produce a more powerful beam) than the regular incandescent filament lamps, therefore the dynamo output will balance their load at lower engine speeds.
I believe that an alternator, unlike a dynamo, produces a fairly constant output throughout the rev range.
It's a fact that our bike ammeters are pretty agricultural and are more 'charge vs discharge' indicators rather than an absolute indication of the true amperage.
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