E3L Dynamo conversion to 12volt failed

[HONDAPETE]

Hi Trev

It seems this thread has created some interest, I have wound the armature at work in between jobs and am ready to solder and test.
You are obviously expert at this and the pics are great, if you were nearer I would have dropped it on your doorstep 
Many thanks for the help and advice
By the way I have done a couple of mags and that is a nightmare.

Peter

[trevinoz]

Good on ya, Peter.
                              Did you make a new field coil while you were at it?
How do you test? I "drop" test and megger to ensure that I haven't got the dreaded earth on a coil.
The badly burnt armatures usually have the end insulation beyond saving so I use longer slot insulation with slivers of thicker paper between slots.
This is not always successful as I have been known to have failures.
You are a brave man rewinding magneto armatures!
It is not too difficult if you have the right equipment, which I haven't.
Let us know how it all went.
           
                  Trev.

[HONDAPETE]

Hi Trev
I reassembled the dynamo last night and it motors fine now, I ran it up in my lathe, which is too slow really, and it has output. I have not rewound the field coil yet so that is the next thing to do and then test properly. I bound the windings and varnished it today now I know that it works.
Yes I meggar the windings I also have a "Growler" I expect you know what that is, for testing for shorted turns. Dad had it in his shed for about 50 years so its mine now.

Again thanks for the help.

[trevinoz]

G'day Peter,
                       Thing's are looking up!
You will get better output results if you make an adapter for a socket and drive the generator with a drill.
I have a pistol drill which supposedly runs at 2500 rpm variable.
I load test generators after completion by connecting a regulator and battery with a headlight.
This saves fitting to a bike and having to remove it again if it doesn't come up to scratch.
I haven't used a growler since my tech college days, in fact where I served my time didn't have one so I didn't get much experience with them.

   Trev.

[HONDAPETE]

Trev

I made a former and rewound the field coil today, taped it with cloth tape and formed it to shape around the pole piece and it actually fits into the yoke, so nearly there.
Peter

[HONDAPETE]

Hi all,

Dynamo all finished and works a treat many thanks for all the help.
Regards Peter

[trevinoz]

That's good news, Peter.
Hopefully Yuniel will get his going as well.

  Trev.

[Topdad]

Hi all, just to say I'm amazed at the depth of knowledge shown by you guy's no currying of future favours but I've only been on this forum for a couple of weeks and i'm seeing you doing things I wouldn't contemplate . Winding a dynamo ....a black art!! done in a shed? mind boggling when I wanted mine changed to 12v I asked sean hawker Hawker electricals as was , to do it as i'm obviously a wimp! they did a great job bit I've got another one that is duff and i think I'm goner have a look instead of selling it to that DUNN guy for peanuts.  hope you don't mind some really daft questions as I can feel 'em coming already ,best wishes Bob.

[bsa- bill]

Ah yes Bob there are some really skilled members on this forum, however a lot of us learn from them but still need to farm stuff out at times, the secret is not overstepping your abilities (too often that is)

[fump]

That is all very interesting to me as I am attempting to rewind a E3N (6volt). I reckon that each loop has 18 turns and am wondering how to fit the 36 wires I think are required into the slot!

Can someone confirm that it is indeed 18 turns per loop? Looks like "mission impossible" to my untrained eyes.

Cheers
Roger

[manosound]

Roger,

I can't speak to the issue of turns on the dynamo armature, but I can offer you a quiet welcome to the forum.

 ROGER,

 WELCOME TO THE ONE AND ONLY BSA A7/A10 FORUM!!!

[trevinoz]

Roger,
             There are indeed 18 turns per coil in an E3N armature.
As long as you are not using too large a conductor, they fit easily.
I quite often wind them with20 turns per coil with no issues.

  Trev.

[fump]

Thanks you two gentlemen for the welcome and reply..........Trev thanks for that, I will persevere with the rewind then, it's just that there seems hardly enough room for 36 wires in that small channel! I guess I will have think hard about how to lay them. The old wire appears to be about 0.75 mm.

Regards

Roger

[trevinoz]

Roger,
                Without going to the shed to confirm, 0.7mm is the conductor size.
As you wind, keep it tight and push the conductors into the slots with a piece of insulating board or a piece of Laminex, which is what I use.

  Trev.

[fump]

Thanks Trev............I can only get 0.8mm here or 0.65 mm for some reason, so have gone for the 0.8mm. Have done 6 windings tonight as am awaiting more wire! It's a tight fit. I wonder if 0.65mm would be too small to carry the current safely? It would be a better fit....

[trevinoz]

Steve,
            Use a piece of insulation or whatever which is a snug fit in the slot between the insulation and tap down with a small hammer, I use an 8oz ball pein.
The windings should compact OK.
I just went to the shed and had a look in the scrap bag for original windings and found that the old cotton covered conductors are 0.024" and the enamelled are 0.028".
The 0.65mm should be alright.

  Trev.

[fump]

Trev
Thanks very much for that. I am using the 0.8mm presently and have done six coils and am now awaiting another batch of wire from local supplier as they only had one unit in stock. I modified a plastic paint stirrer and that is doing a good job geting the windings in place. Though it is pretty tight in there, but tests out okay with the meter.
I guess I am not very confident as I have put an AD in the local club mag for a E3N !
Cheers

Roger

[fump]

Well I have done the re-wind but...................... I am geting only 150 mv out of the B....y thing when driven with my electric drill (at about 800 rpm I think). It motors well with 12Volts on it and in the correct direction too. But will not drive a 6volt 21watt lamp, which is no surprise with 150mv out.
The Field coil reads 3 ohms, armature is infinite to earth and all adjacent com segments are connected and the highest reading between furthest segments is about 0.6 ohm. I would appreciate any informed comments please!

[trevinoz]

Roger,
                    800 rpm is a bit slow to test, I use a drill which runs around 2500 rpm.
But, the question is, have you connected the coils to the correct segments?
Connecting just one out will cause very low output. [Don't ask how I know.]
Testing resistance between segments is not much use.
I find that "drop testing" between segments is best as I don't own a growler.
Another problem can be a reversed coil, i.e. one that is connected wrong way round. This will be picked up with a drop test but not with a resistance test.

  Trev.

[fump]

Trev thanks for your reply. I think I under estimated the revs on my drill. I have got it going now there was an intermittant earth fault on one coil. So I had to rewind four coils to clear it! It will light the 21 Watt bulb now and gives 7.8 volts on load.Wonderful!