Charging system mystery (I promise this is something novel)

[levdir]

Hi everyone. I'm starting a charging system thread, and a thousand apologies for that.

My issue is, near as I can tell, a new one, and one that's virtually impossible to Google. My problem is that my new combined reg/rec seems to be outputting 12V flat to the battery. Just try searching for "charging system holds at 12v" or the like and see what you get.

I am running a cheap Chinese reg/rec designed for a Honda GY6 and clones; its pinouts are as follows:

I have the stator and field coil wired up as indicated; the black wire from the field coil is running back to the ignition switch. The black wire on the diagram also goes to the switch. The "pink" wire, red on my unit, goes to the positive battery terminal. The white wire is unused and capped off. For some reason, my battery holds a steady 12V at idle, spiking by only a handful of mV under throttle. If the reg/rec is disconnected, battery voltage drops steadily at idle. I set my idle high for testing and it never went above 12.5V. Any ideas? I realize this is a wildly non-stock application, so if you need more details, let me know.

 

[drewpy]

for starters the black wire should be ground not positive
green wire to field coil not stator?
whats a positive enricher coil? maybe field coil?

does the field coil magnatise?

 

[BBS360]

It looks like the GY6 uses a totally different alternator setup. No field coil, extra coil for CDI ignition.
I'm not sure the reg/rec could be used at all except maybe for the rectification only.

 

[levdir]

for starters the black wire should be ground not positive
green wire to field coil not stator?
whats a positive enricher coil? maybe field coil?

does the field coil magnatise?

The green wire presumably goes to the stator on the GY6; I've got it wired to the green wire on the field coil and the black wire off the field coil to the 12V rail off the ignition switch. The enricher coil is an electric choke on the carb, I believe; I've got that wire capped and going nowhere. I had the black wire running to ground and when it was wired that way voltage across the battery continued to drop at idle.

How do I verify that the field coil is magnetizing? I have 12V running to it.

It looks like the GY6 uses a totally different alternator setup. No field coil, extra coil for CDI ignition.
I'm not sure the reg/rec could be used at all except maybe for the rectification only.

This is the part I'm unsure about. I know the GY6's alternator is physically different, but it still delivers 3-phase AC. It does seem to be regulating; I've read that our alternators can pump out like 45V without regulation. The fact that it's a level 12V across the battery at idle suggests that it's doing its job. I'm just not sure why it's leveled off there.

Thanks for your input so far. I'd like to get this working for my own sake, and if I do I'll be able to amend that diagram for our bikes and we'll have a cheap reg/rec solution. Worst case scenario I get a different unit and try again, I guess.

 

[BBS360]

Looks like there are multiple different stators that can be used on the GY6 motors and they each need specific regulator/rectifier units... so finding wiring diagrams to compare the entire system to ours isn't so easy.

It does look like the green wire is a ground, as per this thread: http://totalruckus.com/phpBB3/viewtopic.php?f=116&t=23567
The white wire does appear to be for the electronic fuel choke/enricher. Useless on our bikes.
The black wire I'm not 100% on. Some wiring diagrams seem to indicate that it's an output for lighting only. Some posts suggest the GY6 uses AC voltage for the lights so it might be a regulated AC output.
Some other posts seem to suggest that it's a voltage sensing wire for the regulator. Some bikes will monitor the voltage after the ignition switch, outputting slightly higher voltage to compensate for volt drop in the wires and poor connections.

As for the field coil...
To test the field coil you can do the razor trick. With the engine running the field coil should have a strong enough magnetic field to hold a razor blade against the alternator case.

The word "regulate" means two different things between our bikes and the GY6 (or any modern PMA bike).
Our bikes "regulate" by controlling the field coil and the stator's AC output is simply rectified to DC.
The GY6 motors have PMA alternators with no field coil and electronically regulate the stator's AC output by converting to a specific DC voltage.

There are no wires on this unit that will properly control the field coil.
For a bit of a debate on the necessity of actually controlling the field coil see this thread: http://www.xs400.com/threads/combo-regulator-rectifier-79-xs400f.12845/page-2#post-162882
But you can skip all that and see the conclusion in this post: http://www.xs400.com/threads/stator.4845/#post-163645

So these PMA-type regulators can be used on our bikes but a field coil regulator should also be installed. There may be benefits to the setup. The DC regulation is much better, allowing more sensitive modern batteries like AGMs or lithium cells to be used without the risk of damaging them by overcharging.
It runs the stator cooler than any PMA setup, prolonging stator life. Burning up stators on PMA bikes is pretty common.
Compared to PMA bikes the current through the reg/rec is minimized, as-is the current shunted by it, meaning the reg/rec unit runs cooler and also lasts longer.

As for whether this reg/rec unit will work... I'm not sure as long as it's only giving 12V. I'd speculate that maybe miswiring of the regulator is tricking it into converting to an artificially low voltage.

 

[levdir]

Thanks for the detail, that's really helpful. I did some more reading after I sent the previous post (slow day at work) and found, like you said, that this unit isn't designed to manage a field coil. That being the case, I decided that--barring a slight rewire to test an alternate configuration--I would probably need a new unit. I found a combination unit marked for DOHC XS400s, XJ550s and so on, and I double-verified that they all use field coil alts. Now I get to sit on my hands until it shows up.

Thanks again for taking the time to do that looking. I'll report back with my findings once the new part gets here.