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Does anyone know what the voltage output of the stator is? Also, if I convert to DC, using a bridge rectifier, does the voltage drop?
Or ...With a Rectifier, what is the DC voltage output of the stator?
Automotive is usually 13.4V, but that is not necessarily true with the KDX.

Thanks.

ITs an AC output that will run from just under 12v at idle and increase with RPMs (thats why you need a regulator and also why your lights dim and brighten with throttle). Converting to DC the voltage will drop a little, but its trivial. Even with a DC system the stator is going to put out 12v nad increase as RPMs go up, again, thats what the regulator is for. The rectifier in a DC system converts the AC voltage from the stator to a DC one that can then be used to charge a battery and power normal 12V electrics. It is, of course, a little more involved than that to do the conversion, but not terribly (have a read through here)

I understand what you are saying. I'm looking into building an LED headlight and need to know the voltage rating, I'm pretty sure that you are talking about the watts and/or amps, but I could be wrong.

I have tried the rectifier to convert to DC. The voltage drop is horrible.

ecojbr wrote:I have tried the rectifier to convert to DC. The voltage drop is horrible.

OK, here's what I'm thinking......
I want to make an LED headlight assembly for the KDX. I will use a "circuit" board that I custom print and make, three rows of 3 bulbs----one row of 3 bulbs would be the low beam, two rows of 3 bulbs would be the high beam. I'm pretty sure that I can put a "mini" rectifier onto the board, this way I'd only be converting voltage used at the head light itself.
I need to know what the AC voltage output is rated...I know it's a 12v system, but so is a car, but most (if not all) vehicles actual DC output is 13.4v, probably up to 14.4 on newer and high end vehicles. The reason that I need this info, is to get the resistors right, this way I'm not burning any more power than needed.
I am going to practice making a tail/brake light that fits inside the stock taillight housing, but it will not be a printed circuit board.
If I figure the voltage at 12 volts vs 13 it makes a difference in the resistors. If I don't get a FIRM answer, I'll figure at 12V.

On my bike today at 600 rpm I measured 11.8VAC and at 4,000 rpm it was 14.6 VAC. I have rewound my stator FWIW.

bufftester wrote:On my bike today at 600 rpm I measured 11.8VAC and at 4,000 rpm it was 14.6 VAC. I have rewound my stator FWIW.

Perfect! Thank you! I can get to calculating this out now........

ecojbr wrote:I have tried the rectifier to convert to DC. The voltage drop is horrible.

did you use a battery or capacitor?
uprated stator?
best regards
john

I'm going to chip in---but admit that I don't know the mechanism which Kawasaki uses to control voltage out put of the stator----but I'll tell you what I do know and it does seem to 'fit' what buffmaster told you. What I am about to tell you I learned on old English bikes---Triumph and BSA. But electricity is electricity and so I doubt that I'll be too far wrong.

1. A stator has a certain number of windings ----As the magnet in the rotor passes by a stator winding a current is generated in that winding ---the faster the magnet is moving the higher will be the voltage---that's why there is no 'set' voltage output by the stator. The "base' voltage would be determined by the number of turns in the stator windings. The voltage would be at a minimum at 'tickover' RPM and would climb from there as the RPM increased. The voltage would be at a maximum when the engine was turning top RPM. Like buffmaster said---you will need a regulator. The Brits used a 'Zener Diode" as a simple regulator. It's likely that Kawasaki would use a similar type regulator----Here's the way that works----The Zener Diode has one leg connected to the stator output and one let connected to ground. The Zener is designed to 'bleed' off any excess voltage to ground beyond---maybe 13-14 volts-----When the engine is running at an RPM which is outputing less than 13-14 volts then the Zener allows the voltage to stand ----but when the engine RPM has increased and the voltage output of the stator reaches ---say 15 volts- and above---then the Zener will simply bleed off that extra voltage to ground. So the voltage reaching the full wave rectifier remains constant and the output does not exceed 13-14 volts (or whatever value the Zener is set for). Headlight elements are designed for a certain voltage---if it were not for the Zener--or other type regulator you would be burning out your HL elements when you are running high RPM. I don't know---but imagine that LED lighting is also voltage sensitive---so you will want to select a 'regulator" within those limits. You can probably buy a Zener diode at the rating you want at Radio shack----
That's the approach that I would use if I were converting my HL system to DC ---but I have never done that so what I'm saying here is just "theory'---take it for what it is worth

PS-----There should be no---negligible---voltage drop across a full wave rectifier if the diodes are arranged correctly---???? I don't understand why ecojbr has a problem there?

Deseret Rider wrote:I'm going to chip in---but admit that I don't know the mechanism which Kawasaki uses to control voltage out put of the stator----but I'll tell you what I do know and it does seem to 'fit' what buffmaster told you. What I am about to tell you I learned on old English bikes---Triumph and BSA. But electricity is electricity and so I doubt that I'll be too far wrong.

1. A stator has a certain number of windings ----As the magnet in the rotor passes by a stator winding a current is generated in that winding ---the faster the magnet is moving the higher will be the voltage---that's why there is no 'set' voltage output by the stator. The "base' voltage would be determined by the number of turns in the stator windings. The voltage would be at a minimum at 'tickover' RPM and would climb from there as the RPM increased. The voltage would be at a maximum when the engine was turning top RPM. Like buffmaster said---you will need a regulator. The Brits used a 'Zener Diode" as a simple regulator. It's likely that Kawasaki would use a similar type regulator----Here's the way that works----The Zener Diode has one leg connected to the stator output and one let connected to ground. The Zener is designed to 'bleed' off any excess voltage to ground beyond---maybe 13-14 volts-----When the engine is running at an RPM which is outputing less than 13-14 volts then the Zener allows the voltage to stand ----but when the engine RPM has increased and the voltage output of the stator reaches ---say 15 volts- and above---then the Zener will simply bleed off that extra voltage to ground. So the voltage reaching the full wave rectifier remains constant and the output does not exceed 13-14 volts (or whatever value the Zener is set for). Headlight elements are designed for a certain voltage---if it were not for the Zener--or other type regulator you would be burning out your HL elements when you are running high RPM. I don't know---but imagine that LED lighting is also voltage sensitive---so you will want to select a 'regulator" within those limits. You can probably buy a Zener diode at the rating you want at Radio shack----
That's the approach that I would use if I were converting my HL system to DC ---but I have never done that so what I'm saying here is just "theory'---take it for what it is worth

Spot on! And indeed, the stock regulator on the KDX is a zener with supporting circuitry (if you ever get bored and have one laying around, tear open a regulator...kind of like cutting one of those old, rubber band wound golf balls ) I have rewound my stator using 18 gauge wire, so have fewer turns on it than a stock one, which results in a slightly lower "base" voltage, but the larger gauge allows you to carry more current (which is what you really want anyways...just think of a garden hose where the water is the electricity, a bigger diameter hose will move more water, but at a lower pressure)
THis is the reason most DC conversions utilize a battery. When RPMs are low, voltage is low which results in dim lights. Utilizing a battery it makes up the difference in voltage and keeps the lights brighter than they would be on the stator alone. Once RPMs go up enough that the circuit is "bleeding off" the extra voltage, the battery absorbs the extra as a charge, but the lights stay about the same if the regulator is doing its job.
If all you are doing is a headlight to DC the issue you'll have is that the stator has one leg tied to chassis. So you could run a full-wave rectifier with one leg attached to chassis, but you would have to make sure not to ground the DC output of your circuit to the frame. (see this thread. Not a problem is you're going to just run a bank of LEDs. You could certainly make a board that fits within the stock headlight housing, and with LEDs where they are now there is a possibility of getting a lot of light output. Harder part will be building reflectors to help form the beam instead of just lighting up everything 10' in front!

bufftester wrote: You could certainly make a board that fits within the stock headlight housing, and with LEDs where they are now there is a possibility of getting a lot of light output. Harder part will be building reflectors to help form the beam instead of just lighting up everything 10' in front!

My plan is to NOT use a reflector. I want to, but not sure if I can, use the rear part of the housing to mount the circuit board and replace the stock lens with a piece of Lexan. The dock lights that we use at work are built this way and brighter than anything that I would want on my bike, so I'm working off that idea.
The power output is the most important part to me right now....well will be when I go to build...since I don't want to over draw the circuit but still want plenty of light, especially at night.
Like I said, I will practic by making a tail light first and then move up to the headlight. If all else fails, I will buy a tusk conversion kit to help me with power.

Not that I fully understand, but using the same rectifier I used on my XR's there was definate voltage drop. I never used a battery or cap. Was trying to get a horn to work with lights also. As for LED's go. I am running two 3watt mr16 led's in the Acerbis DHH housing on my 03 KX 250 off of it's factory 14wt powerjet stator. If LED is what you are looking for, the KDX stator will easily run two 9-12 watt bulbs that are impressivly bright.

ecojbr wrote:Not that I fully understand, but using the same rectifier I used on my XR's there was definate voltage drop. I never used a battery or cap. Was trying to get a horn to work with lights also. As for LED's go. I am running two 3watt mr16 led's in the Acerbis DHH housing on my 03 KX 250 off of it's factory 14wt powerjet stator. If LED is what you are looking for, the KDX stator will easily run two 9-12 watt bulbs that are impressivly bright.

what rectifier did you use? was this a reg/rec? or just rec? if rec did you leave the kdx's regulator in place? did your xr's have battery's?

I know the trail tech reg/rec I am using is designed to be used with a battery or capacitor, if you don't use either you will struggle to pull 6 volt and the lights will dim with a voltage drop when you rev the bike, soon after you will burn the unit out!

best regards
john

I use rectifiers from yamaha outboards. Mainly because I have a supply of them.

ecojbr wrote:I use rectifiers from yamaha outboards. Mainly because I have a supply of them.

ok,
If you could answer a few more of the questions I posted above it may help with what you was doing wrong.
best regards
john

Yes they are rec/regs. There really isnt enough room on the hybrid for a battery. And the factory reg was removed. I did notice that with my xr 600 I had voltage drop as well, not as drastic but it had a 200 watt stator also. When I added a 4 battery I had no problems with lights at idle. With the dx I never tried a battery. I was just wanting to run my headlight and a horn for the a@@ holes that refuse to let me around in hare scrambles. Mostly younger riders who had that "I am gonna win it all" frame of mind. They will learn but I thought it would be funny

ecojbr wrote:Yes they are rec/regs. There really isnt enough room on the hybrid for a battery. And the factory reg was removed. I did notice that with my xr 600 I had voltage drop as well, not as drastic but it had a 200 watt stator also. When I added a 4 battery I had no problems with lights at idle. With the dx I never tried a battery. I was just wanting to run my headlight and a horn for the a@@ holes that refuse to let me around in hare scrambles. Mostly younger riders who had that "I am gonna win it all" frame of mind. They will learn but I thought it would be funny

thanks for the info

you really need to use a battery or capacitor, you should be able to fit either in the air box, it will make a massive difference.
here is a pic of the battery I am using.



best regards
John

Would love to find a place for that in the kx airbox. There's really no room. Where do you grt a battery like that?

look here-------batteries of all sizes
http://www.batterymart.com/c-sealed-lea ... eries.html