The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: worntorn on 27.08. 2020 16:14
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A good friend of mine is restoring a Superflash that came to him in running but rough condition.
Twelve years ago the previous owner converted the bike's Lucas dynamo to 12 volt. He purchased a 12 volt armature, 12 volt field and Podtronics DC reg from Walridge Motors here in Canada. This was as recommended by Mike Partridge, owner of Walridge. The system worked flawlessly for 12 years during which time the machine had much use. In fact the previous owner did not know it was a Superflash, he just thought it was another tatty old A10 and proceeded to ride the wheels off of it!
My friend identified it as a Superflash then paid quite a lot for it.
A couple of months ago he asked if I would consider swapping my Super Rocket's 6 volt armature and field for his 12 volt setup.
I explained that my 6 volt E3L was not working, only putting out 2 volts, but he was undeterred. He is very capable, having built replicas of several rare old bikes from nothing more than raw materials. ( Velo Roarer Supercharged, AJS V4, Vincent A twin)
So I dropped my E3L off at his shop so that he could get whatever he could from it.
He found that the armature was good but the field had a broken wire. He had another 6 volt field so no problem there.
He rebuilt my dynamo at 12 volts, installed new bearings etc. He set polarity for negative earth, which was his preference and generally would be mine as well.
The problem is that the Podtronics regulator is positive earth only. Of interest, it is of the converting type, 6 to 12 volt.
I would have expected a straight 12 volt Podtronics since the dynamo had been converted to 12 volts. Apparently the reg was also recommended by Mike Partridge.
It has lasted so Mike obviously knows what he is about.
I thought it would be nice to leave this freshly rebuilt dynamo intact and stay with the negative ground, so looked into purchasing a new Podtronics 12 volt DC reg in negative earth polarity.
Not so long ago Podtronics did make these in negative and positive ground, as well as the conversion units in either polarity.
They no longer make any of those units.
The only DC regs they make are 6 volt, but they do offer a positive ground model and a negative ground model. Good to know but of no use in this application.
Is there someone making a negative earth solid state straight 12 volt reg today?Dynamo Regulators perhaps?
Alternatively I could take the dynamo apart to change the polarity back to positive ground, then continue using the Podtronics unit.
Thanks
Glen
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Surely all you need to do is 'flash' the dynamo to reverse polarity?
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I read that online and tried it, several times. Nothing changed, it's still producing power at -earth when rotated counterclockwise.
Dan says it has to come apart for a polarity change.
Ive used the flash to wake up a sleepy dynamo, that was successful.
Glen
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If it's a 12v negative earth regulator, the DVR2 is a popular and reliable choice on here.
Bulletproof unless you neglect to make a very good connection with the earthing wire, it fries them pretty quickly. Fit properly and forget.
I prefer negative earth simply because it's easier to get bits and pieces as it's the industry norm these days.
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As RDfella says - it's a 2 min job to get the original polarity back, costs nothing and job done.
Which does work Glen, ref your latest concern - it is, truly and honestly cross my heart etc etc, quite unnecessary to take the thing to bits to change it. Dan is, on this point, misinformed, like Bogart in Casablanca!
Polarity reversal may not suit though, if intending to run modern electrical accessories that only work on negative earth . . .
. . . in which case there are several decent regulators that would do the job. They mostly work at either 6v or 12v depending on preference - there's nothing inferior about that, if it's a concern, and most of us would count it an advantage.
The most popular one probably among folk here is the DVR2 from Dynamo Regulators whom you mention. Tried and tested to the nth degree by dozens of people here, I personally have 3, others may have whole shedsful!
The JG range might include a '12v only' unit (it used to, but not sure now). But, if you went that way you'd need to rewire your field coil connections to go between D and F, not D and E, and verify you've got the direction of rotation right when you've done it. That's because JGs were designed for Miller systems originally.
It may be worth adding that new finer-wound '12v' armatures and field windings are actually easily available (and reasonably affordable) over the counter, as are brand new standard-wound items.
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I'm going to give the flash method another try. Perhaps I did something wrong.
The dynamo has two wires, a green and a yellow.
When rotated CCW the yellow wire shows
voltage to the dynamo body.
The green wire does not.
This is with multimeter positive probe on yellow wire, negative probe on dynamo body.
So that is negative earth, as intended.
For an attemptes reflash to positive ground, I connected battery positive to the body and touched
a wire from battery negative pole to the dynamo yellow lead, a few times. Some little sparks occurred, as expected.
No change, it still produces power at negative ground polarity.
Am I doing this incorrectly?
Glen
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The yellow wire is D, the green is F for field, or should be. The dynamo cover is marked F & D usually, so you can check that.
Disconnect them, get yourself about a yard of decent weight wire, and have a read here, which is the best explanation I know of -
https://www.matchlessclueless.com/electrical/lucas/repolarising-lucas-dynamo/
Afterwards, you'll need to reverse the wires on the ammeter, as it will show + for - and vice versa.
As the guys says at the end, as you pat yourself metaphorically on the back - 'Easy, wasn't it!?'!!
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... the DVR2 is a popular and reliable choice on here.
And can be hidden inside an original regulator box. ;)
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Thanks, will give it a try and report back.
Glen
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... the DVR2 is a popular and reliable choice on here.
And can be hidden inside an original regulator box. ;)
*smile*
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That worked, thanks so much.
Very glad I asked the question and did not take it apart!
Glen
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Phew! Good news!
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It will be nice to having working lights on the bike and the 12 volt is a bonus.
Will fit one of those latest greatest BPF LEDs with the improved focus, then run it at all times. They are only 12watts and very bright to oncoming traffic.
Not bad at night either, almost on par with a 60watt halogen. The 60watt h4 still has a slight edge for night riding, but daytime safety is more important for this bike.
I thought it strange that this system uses a 6to 12 conversion reg along with fine wire12 volt armature and fine wire 12 volt field.
Glen
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worn torn. please read previous bogs as the questions you have have been well discussed. no offence intended.
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I've a C11 with the short 35w e3 6v dynamo and wanted to try a h4 led headlight, so, keeping the rest of the bike at 6v simply put a 6v to 12v inverter (£5 from China) into the headlamp cicuit. Amazing difference.
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worn torn. please read previous bogs as the questions you have have been well discussed. no offence intended.
Sorry to revisit topics already covered.
I did a search last night and came up with a couple of threads which filled my head with the same conflicting information I already had onboard. After a half hour of reading I was no further ahead.
So I asked the question today and it was 2-0 for the reflash as opposed to rewire. That worked out fine.
Glen
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'flash as opposed to rewire . . .'
Rewiring the field or brushes will reverse rotation Glen but won't affect polarity.
An easy way to ensure both polarity and rotation are as required if the need arises again is to motor the thing using a battery. When it works as a motor turning in the direction of drive on the bike, with the preferred earth, you know all is going to be good (if the guts are of course). To do that, you just connect D and F together, hook the joined wires to the chosen LIVE side of a battery, earth the body to the other terminal and let the thing motor for a few seconds.
If it turns the wrong way, reverse EITHER the two wires off the field coil which go to F terminal and earth, OR swap the brush connections round between D terminal and earth - but not both or you end up where you started. (Some dynamos have one brush holder permanently earthed, which precludes swapping the brushes, but not an E3L.)
Info on some of these topics is a bit muddled and can be hard to dig out, I agree. There are also dodgy bits, as ever. The site I referred earlier is good, and the book 'Classic Motorcycle Electrics Manual' by the same guy, Dr James Smith, is quite excellent. A modern bible pretty well. No connection, I'm just a satisfied reader.
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Yes, the link you provided was excellent thanks Groily.
I was dimly aware of flashing to change polarity from reading up on dynamos 17 years ago when my Rapide arrived with a dead Miller dynamo after 3 months at sea.
For this go around I had some fresh misinformation plus similar found on the old threads. I also contacted the previous owner of the bike who suggested just hooking it all up and running it with negative earth dynamo feeding positive earth solidstate regulator, but isolate the reg. I'm pretty sure that would make smoke!
With your help I think I've got it all reasonably straight now.
The dynamo is on the bike and happily charging a 12 volt battery at just a touch off idle. Seems to have very good low speed output. Standard chain drive.
Was thinking about fitting one of the belt drives then searched here and read of pulleys coming loose after a few thousand miles in more than one instance.
This setup doesn't seem to need extra speed. Once the LED headlight bulb is fitted it should be loafing, leaving enough for the heated vest
I sometimes use.
Glen
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hi worntorn, sorry you did not find the information you needed from previous posts. perhaps , like me ,if you have a bench and vice you can set up a testing rig using a drill, cut off extention to fit chuck and i think 3/8 or 5/16 ? cant remember, whit socket. set up the dynamo with f and d connected together to a bulb via bulbholder and common earth. a reversable drill is preferred so you can spin in both directions which relates to the problem your having. so many times i ve found problems with the dynamo down to sticking brushes , corrosion, bad connections, loose screws , bad or dirty commutator, poor threads or assembly which you dont notice so much fitted on the bike. when you happy with the dynamo output you can hook up the regulator correctly wired and measure the output also on the bench. once you achieve the light going bright using the drill its a eurika moment. i tested half a dozen dynamos i had lying around one afternoon and split them up as rainy day work and spare working then forgot where i put the good spare ones.
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I didn't find the conclusive info needed when searching, but did get exactly the info needed in this thread.
Spent yesterday tidying up wiring, replacing corroded bullet connectors etc.
The bike had been without working a working charging system and lights for many years.
Also installed a SparkBright voltage monitor in the headlight.
It is all working well, bright lights and decent dynamo output @ 12 volts.
It's not an Alton for output but with a very bright 12 watt LED
headlight bulb there is enough power in reserve to run a 35 watt heated vest and keep everything balanced at about 45 mph.
Without the heated vest the monitor goes to green (13 volts) at 35 mph in top gear, slower than I normally run in top.
Very happy with that.
Glen