Single phase alternator winding pattern

[stinkwheel]

This is complex. I'm a bit out of my depth with it.

The alternator I have on my Enfield is an aftermarket one. As purchased, it was made with an AC/DC setup. What turns out to be a very small, single DC coil to slowly charge a diddy battery and a much meatier three coil AC output for lighting. It turns out it was setup with an AC regulator and a halfwave rectifier for the DC.

Here's the stator I have:
https://lh3.googleusercontent.com/pw/AM-JKLWCge-Mx9EhF3Nmn3vMO5gIfEoOvnzOp69Lt_3aTPwpq1vUQ0V16rUPyXWB51CK4zdS18qKLudhSJCiT7_b97994Cki5RQVVPV75v6dQxgv7GYMb_ZSc78P5_mK6SZ9i-wg3TelyY2oLYyENYlsAGd6=w1182-h886-no

The top coil, wrapped in black is for the ignition and is totally seperate.

It has a white, yellow and black wire. Black is ground.

The AC comes in on the yellow, takes 20 clockwise turns round the left coil, 100 turns anticlockwise round the bottom coil and 100 turns clockwise round the right coil and terminates to ground.

The DC comes in on the white, takes 80 turns clockwise round the left coil over the top of the AC winding then terminates on the yellow.

I want to convert this to single phase DC. I have a proper, single-phase DC reg/rec now.

The company now sells a DC stator for this exact purpose. Thing it it's a) out of stock and b) £150.

It does however use exactly the same base plate and rotor. Here's the only picture I can find of the DC stator:
https://lh3.googleusercontent.com/pw/AM-JKLWLnA2-pVsDVjtziR0Rtao4SFq7OrYSTSdBWE4l-bAxs1RirhA2tH2E0rs8V0r1j-hkToZFREmpTFcCcemMTl8izaZ1el1cdyExIfccILFWmrwClpkokdAJvPe69jI11KOYStNLm66cYTWPKa6yfPcF=w693-h462-no

I think it's a fair assumption each coil still holds 100 turns and is using the same gauge wire. My question is, how should I wind it? I see two options (but there may be more);

Option 1:
Wap 100 turns round each in turn. Then take the end back to the other output.

Option 2:
Wrap 50 turns round the bottom and left coils, `100 round the right then come back with another 50 turns on the bottom and left coils.

I have a feeling it actually makes no difference?

Then direction? Looking at the picture, it seems as if the left and right are wound anticlockwise and the bottom is wound clockwise but it's not easy to see. This roughly fits with how they did the AC output on the original (bottom wound the opposite direction to the left and right).

Or am I going to set fire to my bike?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[steve the grease]

Thanks for the drawings. You need to take phasing into consideration as windings could add or cancel each other out. If the curves lay on top of each other they will add - doubling the current ( on the assumption that the amplitude is the voltage) if the curves are in opposition they will cancel each out, wholly or partially depending on phasing.
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All the above is my personal opinion, you can see my lips move, but I'm talking out of my arse.
I've been riding, and fixing , bikes for 50 years, in that time the more I learn, the less I am absolutely sure of.....

[stinkwheel]

I thought direction might make a difference because a north pole magnet may be going over one coil as a south goes over another.

I did some fag-packet sketches of what i have now and what I'm proposing.

https://lh3.googleusercontent.com/pw/AM-JKLXQFSyN4ufht9KSKzC1SkDGiboJcG7spq5bwogo2vG4M-yjccmCRG2ohrv978v9WsSB1NG-Y57jAp4YpTVZmU4jbJSkZMqxnQDafHp0Qg3s8TGpoEbSLpXlsr6qVNzbEcv0n7XquNl51jyXIEO6ZU6p=w499-h886-no

Or should I be paralelling the windings. Like this?
https://lh3.googleusercontent.com/pw/AM-JKLWO-xI6lrM43pJ0gVd4S3Vg-frSgQ8lcVwGs7AEeLdbbsvThSDHL3S3_G-1JwSlwPgqjPm3fku-BqwyHQoyfOv3cVIAhkfgmgvNBEjL7jIoyc7PLGeYwWf7hJeJx1iGKt8nkryIjQpv2riZ8NvYh_mY=w1576-h886-no
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

Aha.

A mate just came up with this from an electonics textbook which seems to fit the ticket. Effectively 100 round each and back to the start with the "bottom" coil wound in the opposite direction to the two side ones.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[WD Forte]

I find this thread prompts questions
Are you going for a full 12v negative ground system
for both lights and ignition as used on most bikes?
this would make many common(cheap) electrical parts available
to you.
Its what I'd do
or is this a part old, part new hybrid type thing?
what is the expected load?
why single phase?
how many magnets on the rotor?
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bikers smell of wee

[Pete.]

[stinkwheel]

I should say, I've unwound the stator. it's the only way I found out what was going on. I was expecting a straight single-phase setup. Metering it suggested a short in the windings. it turned out that the lighting coils earth to the chassis and that little 80 turn single coil on the left is the only charging output

The top black coil is nothing to do with the charging system. It's an integrated ignition generator coil and hall effect sensor which is connected directly to the CDI on a stand-alone circuit. It both produces and times the spark. This works very well and reliably. The other three coils deal with the lighting and charging.

My 12V LED lighting system draws 2.1A total when running off a battery. That's full beam, brake light on and flashers running. Yes I'm going for 12V negative earth. I'm using a capacitor in place of the battery. The rotor is fully enclosed but I believe there are eight magnets.

It's all a bit of a workaround. These bikes were originally designed to run on a magneto mounted behind the engine. They changed them in the mid 60's to charge from a standard lucas alternator on the end of the crank but there was no room for the points so they kept them on the end of the shaft that used to run the mag.

This is a performance engine so the 11 degrees of backlash you get on the standard ignition timing gears is unacceptable. This is the only system that can run both charging and ignition off the end of the crank but space is very tight (it was originally designed to only have the primary drive in there). The rotor diameter is small and there isn't much space for the charging coils. As such, the ability to generate power is a compromise.

[Pete.]

I had no idea that the LED drew so little.

When you un-wound the stator did you find any fault or evidence of shorting? Any portion of the winding wire discoloured? Usually a short in a coil makes at least some of it turn black and crispy.

You say that the coils are dirty-earthed through the base of the stator? Bit poor really it could possibly be the source of your fault. It's a thing that work fine when it works (which is most of the time) but it much more reliable when loom earths are used hence why all those 70's Japanese bike indictors with just a feed wire and dirty earth return were replaced with 2-wire units.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[stinkwheel]

[WD Forte]

Its probably a project that needs some experimenting
and woudl love to put my scope on it but
my initial thoughts on a single phase setup would be to
wind all the bobbin in the same direction as in your proposed setup pic

This cos as the coils are at 90 degree intervals and the rotor has 8 ( or 4)
magnets, all windings will be swept by the same N or S pole at the same time

Make sure to sleeve and insulate the wire from the engine body(ground) and run both
tails to something like this which I assume/hope has a full wave bridge rectifier inside
as well as voltage regulation

https://i.ebayimg.com/images/g/~EwAAOSw5W9e62Zp/s-l1600.jpg

https://www.ebay.co.uk/itm/313119747851?hash=item48e7642f0b:g:~EwAAOSw5W9e62Zp

On the output as well as a big cap, I'd add a smaller secondary cap for extra ripple smoothing
as leds tend to react a lot more to voltage variations than an incandescent blub.
I'd consider using a weeny scooter battery if voltages allow as this can help smooth out voltages

I can only guess but comparing it to similar setups I reckon you may get say 70-80 watts/6A-ish out of it
which is enough to run a 20w headlight which will be fookin bright!

Be wary when buying led headlamps as I've seen many sellers state the equivalent power rather then actual which can be misleading
and say its 100W when in reality it uses 20W of real power
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bikers smell of wee