Did you hand wind that coil?
Sorta. I made a pseudo-gadget with turns counter that clamped onto the carriage of my lathe, and fed onto the spool, which was mounted in spindle with a C5 collet. It was by no means exact in positioning, but it worked out dandy.
Here's the thread, dunno if the pix are visible without registering, but hope so:
https://www.smokstak.com/forum/threads/1a21-generator-24volt-generator-relay.199262/#post-1657293
The EMGO coil seems to be working fine.
I realized replacement China so-called "regulator/rectifier" actually did not regulate the voltage at all.
That must have caused premature battery (AGM) death.
Now I have step down DC-DC (from China, of course) as a voltage regulator.
Yeah, well... MOST motorcycle charging systems work on the design principle invented by a feller (who's name I cannot remember) and implemented into Mercury Outboards' product (somewhat against Carl Keikhaefer's desires) through the spearheading of his chief engineer and right-hand man Charlie Strang.
The permanent magnet stator spins inside (or outside) a stator ring with many polepieces and windings. The result is unregulated AC. This AC comes out of the rectifier to a rectifier-regulator unit. It doesn't 'rectify' so much as it just 'chops off' excess above a certain voltage... it is a 'crowbar' regulator of sorts.
My GN400 (and you know 'em well) was built with a 6v system... a permanent magnet rotor, and a stator to a 3-phase regulator-rectifier.
When I built it into a 'cafe-type', I nixed the battery, and just about everything ELSE electric... I left it with a headlamp and a taillamp that are basically just 'on when running'... and the horn is there (but just for looks).
I used a very large headlamp bucket... I THOUGHT it was for a GL1000, but I just found it on the ground at a motorcycle boneyard, it looked right, so I snagged it... Might'a been from a '70's Yamaha, or Suzi, I really don't know, but it's 12v.
Here's how the regulation scheme works:
AC pulses come into a rectifier on three phases, and they're 120 degrees out of phase for each (like common 3ph power). The rectifier chops the bottom sides of the waveform, and 'flips' them to the top... so now there's six pulses going up, every 60 degrees.
After that, is a very stout transistor (typically a MOSFET) who's GATE is a zener diode set to around 14.6v or so. Any pulse that exceeds that threshold causes the transistor to short the stator's output to ground, until voltage drops back down below 14.6
So yes, when voltage gets that high, it actually SHORTS the stator's output to ground.
If that seems wildly dangerous, consider this:
The stator is an induction coil. It has internal resistance, so current flow through the coil will NEVER exceed applied voltage divided by R. Let's say that the STATOR's total design output is 10A at 14.6v... that's 3.33A per phase. 3.33A at 14.6v means the winding is at LEAST 5 ohms, and output is around 40w. In REALITY, it's a 3-phase stator, so that coil could be as low as 3.5 ohms or so between centerpoint and each leg (because the other two are resistive too, right? Regardless, at full-snot, by virtue of resistance, the stator's output will NEVER exceed 14.6 / 5 = 3A or so PER LEG.
Now, as engine speed increases, FREQUENCY through the stator increases. Since the field is a permanent magnet, it doesn't increase or decrease, so that means stator VOLTAGE output increases with speed.
At least, until the inductive reactance of the stator coil assembly (the coils, wired in WYE, and the stator frame being made of silicon steel with some level of permeability, right), as frequency increases, voltage does, until you hit the 'brick wall' created by 2piFC... and at that point, output starts to drop FAST.
A motorcycle needs most of it's charging current available just a smidgen above idle, and it needs to be able to hold that 'till about 2500rpm or so. The VOLTAGE at that speed, though, is kinda low... usually they're just BARELY AT charging voltage (14.2) at idle or just above... which means full AVAILABLE current flow to the auxiliaries and battery, and as soon as the throttle comes up, voltage starts climbing. By mebbie 3500, you'll be approaching cutoff voltage of 14.6... but by 4500, inductive reactance starts to rise rapidly, because rotating frequency is climbing... but CURRENT is starting to fall off... consequently, VOLTAGE is 'flat lines'. Essentially, XsubL , in conjuction with the speed of the spinning rotor, has caused the stator to become magnetically self-saturated, so the rectifier's regulator block doesn't have anything to do.
It is extremely fascinating to see all this electrophysics in operation... an amazingly simple circumstance that occurs as a natural product of applied physics.
I MADE the shunt regulator unit for my GN. I used a 3ph rectifier, a MOSFET and a zener diode, set it for 14.6v. Engine starts, my system voltage is about 5v, and the headlamp glows dim. Bring up the throttle, and it gets brighter. It's best above oh... whatever speed my tailbone best transmits vibration to my skull... I'm asking a bit more of the stator by going to six volts, but it hasn't fried anything yet. When following, it's not hard to tell when I've shifted gears... headlight goes bright on downshift, dims on upshift! ;-)
Taillight is LED... it's always bright. Mebbie I'll replace the headlamp with an LED too... back when I 'built' that pig, LED headlamps didn't exist.
Oh, and yes... AGMs do NOT like 'noisy' rectification/regulation. Even when the reguator is working 'right', AGMs tend to be intolerant of ripple. Adding a couple capacitors across the leads where they connect to the battery will help... and having a resistive load (ie. don't replace 'all' your incandescent/halogens with LED) will help.
