Scooterotica

Hi, I am in the process of having a go at rewinding my own stator and have become aware after a bit of research that there are design issues which I do not fully understand. So, I thought it would be an idea to start a thread where I can document my progress and hopefully attract the wealth of knowledge evident on this forum.
I am currently running a full DC conversion using a BGM stator as the basis but fitted with 2 SIL lighting coils following damage to the originals caused by one of the mag housing nuts coming undone. I then had a SIL stator rewound at West Country Windings which I fitted and was very happy with the improved output. Unfortunately the windings were destroyed within 150 miles on the way to the Euro in Ireland. West Country rewound it but TBH I was not happy with the way that it was done, not bobbins were used and I was reluctant to use it with the coils wound directly onto the powder coated laminates.
So, I have removed the windings in an attempt to understand how the additional output was achieved and I have been donated 2 duff SIL stators to use for experimentation. Here’s the West Country Stator before:



And with the windings removed


My observations so far are as follows:
Coil wire gauge is 1.25mm (18 AWG) on both the West Country and the SIL
Coils are wound in alternating directions Clockwise (C/W) and Anti Clockwise (Anti C/W) on both stators. Counting from the Pickup in the direction of flywheel rotation, coil 1 anti C/W, coil 2 C/W, coil 3 anti C/W and coil 4 C/W. This has been explained on another thread:

firekdp wrote:Coaster, the coils are alternately wound because, at any one time there will be an opposite pole affecting them. A north magnetic pole will will generate an opposite polarity to a south pole. If the adjacent coils were wound the same way it would be like connecting batteries with the positives together, ie no current would flow. As you're winding lighting coils it doesn't matter which direction you wind them, as long as they alternate.

The next thing I noticed was that there are 2 different sizes of bobbin used, coils 2 and 4 are significantly smaller than coils 1 and 3 with correspondingly less turns on them. Im not sure why this is, it could be due to proximity to the adjacent coils but I’m not so sure.
My next move is to unwind the coils on one of the donated SIL coils (thanks to Toddy, Soulsurfer and Storkfoot) and rewind using at least the same number of turns as used on the West Country stator. The temptation though would be to add as many turns as possible without fouling the flywheel but is it possible to go too far? I know of Hysteresis losses in inductor cores (magnetic saturation/inertia) might that cause excess heat in the coils?
Anyway, enough conjecture for now, all thoughts/ theories and suggestions welcomed, my electrical theory is limited to a City & Guilds taken back in 1972, it wasn’t very clear then and is VERY cloudy now.

i for one will be watching with great interest ..........next instalment please

Good luck with your research and development Col

Col, I understand (Mark will probably confirm) that WCW did experiment with adding more windings to the point where the best output power moved from the rev range where it was most beneficial and that the end result I believe Mark is using on his S1/2(?). The readings may even have been posted on here...

soulsurfer wrote:Col, I understand (Mark will probably confirm) that WCW did experiment with adding more windings to the point where the best output power moved from the rev range where it was most beneficial and that the end result I believe Mark is using on his S1/2(?). The readings may even have been posted on here...

Yes Mike, I was following that thread with interest, I got the impression that they had a few goes at it. My Google research suggests that adding only a few windings can make a big difference. My West Country stator gave similar readings as it undoubtedlt benefitted from the R&D

Ahhh, what you are looking into was pretty much the excellent Tony Mc feature (input from M.S. on here as J1MS... or something like that) that was published in JetSet many years ago, which dealt with rewinding a 12V electronic stator. I can't remember if the feature was for an AC or DC output but it could be applied either way with the DC (Wassel?) 2nd earth wiring being used by many. It was written along the lines of the WSW idea where the excess of V (well over 12V) of most 12V stators could be better employed by using a thicker wire to provide closer to the min. 12V required but to increase the Amps... so increasing the final wattage output (W = V x A). I rewound my own stator by hand and it works very well... I'll post some photos at some stage (or email them to you to post!... email address please?).

Basically, this is also the basis of the increased output BGM stators.

There are 2 sizes of bobbins simply so that they can be fitted to the laminate core without coming to a stop at the same depth. You will note that the core legs are a different depth to accommodate the respective size bobbins.

Adam

Adam_Winstone wrote:There are 2 sizes of bobbins simply so that they can be fitted to the laminate core without coming to a stop at the same depth. You will note that the core legs are a different depth to accommodate the respective size bobbins. Adam

How long ago was that Jetset article Adam, I'd be interested in reading that, especially in respect of the gauge of wire used, to my suprise, the WCW stator (mine at least) uses exactly the same wire gauge as the standard SIl stator that Toddy sent. I was so confused I had to PM him to check that it hadn't been modified Re the bobbin sizes, I can kind of understand the clearance issue to some extend but if you look at the photo of my core above you will see that all fingers are the same length

As for the BGM stator, there might be more windings but it also has 2 more laminations on the core which will be at least partly responsible for the slightly higher output.

I havn't had a chance to do any more yet (tomorrow hopefully) but I have ordered the coil wire (best European spec), winding lacquer, coloured cable, pvc sleeving, winding tape and some new bobbins so should be good to go

Any use?...
http://scooterotica.org/forum/viewtopic ... ator+plate

soulsurfer wrote:Any use?...
http://scooterotica.org/forum/viewtopic ... ator+plate

Cheers Mike, hopefully J1MS will explain the parrallel wiring idea

Adam_Winstone wrote:You will note that the core legs are a different depth to accommodate the respective size bobbins

Having looked at J1MS stator in the link that soulsurfer posted I can see the 'steps' in the legs to prevent the short coils goin on too far. My stator is still covered in coil lacquer and they aren't very obvious.....sorry I doubted