Any electricians/electrical guru's please chime in

[JP50515]

Alright folks so here's the deal....non XS related...so if you're a purist back out now ha.

So I have an XT500 that runs at 6V.

I need to convert it to 12V.

So here's my thing, according to my research the stator is more than capable of producing 12v actually closer to 30v.

So there's a reg/rect kit out there right now by a british company that converts your XT to 12v.

Here's my "knowledge"

So far as I can tell, all it's doing is re-regulating the voltage to 12v and rectifying it at 12v. Then you swap lights, and horn, and whatever else to 12v and you're good to go.

Here's a link to the product.
A bit spendy for my budget.

http://www.ebay.com/itm/Yamaha-XT50...torcycle_Parts_13&hash=item2ecf26fb88&vxp=mtr


So in theory...is that product doing anything different than this (very similar if not identical looking) universal reg/rect?

http://www.ebay.com/itm/320972158615?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Obviously we can't see the internals, but if you were to take an educated guess, is it somewhat safe to believe that if I made up my own little loom for it like the first one that it'd do the same thing?

 

[hmusket]

Interesting question, good chance to learn. Did a quick google search: 6v 12v conversion motorcycle
Got a bunch of hits and even some youtube videos showed up. Going to follow up on it personally, just for the interest factor.

 

[JP50515]

yeah it's actually a pretty cool concept...from what i've read, if your stator can produce over 15V you can clip it back to 12v instead of 6V by just plugging in a 12V regulator. Obviously there's a bit more to it than that in terms of the electrical black magic happening, but I know it's a common thing to do on older bikes.

Report back on your findings!

 

[650Skull]

yeah it's actually a pretty cool concept...from what i've read, if your stator can produce over 15V you can clip it back to 12v instead of 6V by just plugging in a 12V regulator. Obviously there's a bit more to it than that in terms of the electrical black magic happening, but I know it's a common thing to do on older bikes.

Report back on your findings!

And keep us updated

 

[Rgconner]

The gotcha is that if you double the voltage, you half the amps produced.

Amps= watts/volts

 

[XSLeo]

Looking at the parts breakdown of the charging system on an XT500, under the rotor are two windings. One generates power for the ignition. The other powers the lighting.
It looks like a single phase alternator.
As mentioned If the out put power from the lighting winding can make more than 12 volts it can be regulated to 12 volts as a lot of bikes did with a 12 volt zener diode. A lot of the Brit bikes did this. A zener diode is a diode that has a third connection. This third connection is a ground path. When the bike starts the voltage rises and when it reaches the zener diodes preset voltage it bleeds of anything over the preset to ground. Not the best way to do it. I think the newer solid state reg/recs as used in the kit and maybe the Ebay item use a better voltage control than just a zener diode and a resistance. The voltage bled of creates a lot of heat.
What I might do is find where the stator wires hook to the bike and with the bike running check the voltage where it comes out of the stator before it reaches the lighting or ignition.
If it appears to be high enough you might be able to rectify it and regulate it.
They may even have the ignition winding incorporated to help.
With both windings you might get plenty of power to run the bike and charge a battery.
The Ebay item doesn't tell me enough to know if it will work.
On my boat it has a 15 horse engine. It has a lighting circuit. I think it has a max output of 7 amps. I think that's at the max engine speed of 4500-5000 rpms. It is a single phase AC. Fine to runs lights but not charge a battery. I used just one of the full wave bridge rectifiers that get used to build a Radio shack rectifier. With just the one rectifier it puts out DC voltage. At cruising speed it reads a bit high, like 17 volts but I don't spend much time going that fast. At trolling speeds it keeps the battery charged ok.
Leo

 

[resto]

JP,

Interesting potential project you have going there and made for some interesting reading after some google searches.

I agree, your first link was quite pricey, but the second link to just the rectifier/regulator for $6 (shipped, no less) is almost begging for some experimentation. Sure looks like the same piece as in the complete kit and if the wiring color codes are identical, shouldn't be too hard to give it a try. They (Rexspeedshop) claim you don't have to even get at the lighting coil in your magneto, so that in itself saves a lot of work.

I'd take it with a grain of salt though that the $6 rectifier/regulator would work properly with the list of bikes given at the end of the ad. The only thing these bikes have in common is that they have permanent magnet alternators. None have a single phase magneto (for lights and battery) like your XT500 does.

To play it safe though, you should (if you decide to go ahead with this) completely disconnect your existing lighting/battery circuit from your magneto. Wire in the new rec/reg and just use a 12v brake light bulb as the load. Measure the voltage across the bulb at different engine rpm's to confirm that there is indeed proper voltage regulation is happening. If that works, use a bigger load (an old car headlight ?) but keep it under 35watts to be safe and check voltages again. What you don't want to see is voltage over 14.5 volts or else it won't be safe to use that regulator with your bikes battery. Also make sure the rec/reg box isn't putting out too much heat.

Some of the XT500 forum members warn against using higher power (e.g. 45 or 50 watt) headlights as it put too much strain on the magneto's lighting coil at 12 volts. They claim the wire guage on the coil is just too small to support higher loads like that.

BTW, the ignition part of the magneto is totally seperate (has its own coil) from the lighting/battery circuit, so worse case your bike should still start and run after the smoke clears............

As I mentioned, an interesting project. But not without its risk. If you decide to take the plunge, keep us updated.

resto