Subject: Re: [XR650R] Re: Stator rewinding (was Re: Baja Designs Lighting improvement kit) Date: Wed, 03 Jul 2002 19:08:54 -0400 From: Paul Gortmaker To: needsprayer CC: XR650R@yahoogroups.com needsprayer wrote: > > "This is fine if you only intend to drive a 55W bulb, but if you > want more zap (e.g. for 100W) you will need to do a parallel > configuration." > > Paul, > > The wiring of the additional stator posts in series drives my tail > light/brake light (16W), license plate bulb (5W), horn and 100W > halogen headlight bulb just fine. All of the lights are on > constantly. The 100W bulb is extremely bright from a great distance > (verified by my wife) and the intensity at idle is excellent. This is a topic of interest for me, so bear with me as I ramble on :) I am curious if you tried to actually measure the voltage when under load and without the regulator involved. The reason I ask is that the 100W bulbs can appear quite bright, even when operated at a lower voltage (such as 10 volts). The reason I say "without the regulator involved" is that the regulator results in a truncated sine wave output, and for the readings of a typical RMS AC volt multimeter to have any meaning, the input should be an unmolested sine wave. I have an example to back up why I think parallel is the way to go. An XR600 stator (which has same # of poles as 650, in fact it may be an identical stator...) that has been stripped of the 4 poles of #20 and rewound with #18 copper (all poles in series) is able to pull 8.6 VAC with a 100W H3 bulb directly across the stator at idle. The voltage plateaus at 9.9 VAC for all RPMs above approx 1800RPM. This is a true indicator of max power output since no regulator is involved and all power is directed through the bulb. This was with a cold engine. As the engine gets hotter, resistance of the copper wire in the stator goes up and so you will have slightly less power again. Now, should one run a 100W H3 or a 55W H3 on this bike? With the 100W bulb fitted, it seems pretty bright, so that doesn't help. So I set up two identical factory Honda lights (i.e. the "BD lighting improvement kit") with one of each bulbs. There is no question that the 100W is brighter when both are operating at 13V. When I dropped the voltage on the 100W bulb below about 10 or 11 volts, the balance starts to swing the other way, and the 55W bulb at 13V becomes the brighter one. (This is why people run relays on high power car/off road lights - the voltage drop along small wire that goes to the switch and back is intolerable.) Back to the XR600 example - it has plenty of jam for a 55W bulb (which was all that was desired by the owner), but it is not enough to run a 100W bulb at peak efficiency. Splitting it into two groups of 5 poles might have been a better choice, so long as the idle voltage was still satisfactory - I think it would be. If not, two groups of 5 with #20 wire would give more turns and thus a higher idle voltage (tradeoff being a reistance increase of course). I don't know whether BD uses #18 or #20 in their 2x125 stator, but the fact that it is listed as "2 x ..." tells you it is two groups of 5 poles that can be connected in parallel and not just 10 poles in series. Assuming you have determined that a parallel config will have enough voltage at idle (not as much an issue if you have a battery), then a parallel setup wins over an identical series setup for two main reasons. The first is that the overall parallel resistance will be 1/4 of a series configuration with the same wire size and number of turns. Second is that the current through any given pole will be half (for the same overall current load), and so the magnetic field generated by the pole that opposes your flywheel magnet (and thus limits your max output) will be only half as strong as the series case. I've personal experience with another stator example for an XR250 where the difference in output of a parallel setup over a series setup was quite surprising, but I won't bore the list with the details as I've rambled too much already. Hopefully some on the list have found it educational/amusing... Anyway, I haven't any test data on the setup recommended on the internet (i.e. with the stock 4 poles of #20 and 6 poles added in series of #18) which is why I am genuinely interested. You do get more turns per pole with #20, but that also translates into more wire length, and #20 has about 60% more resistance/ft than #18 as well. So I do know that it will have a higher resistance than the XR600 example given above (all #18), and that is why I was wondering if you actually measured the output to be a true 100W or more. Paul. Yahoo! Groups Sponsor [{short description of image}] Home: http://groups.yahoo.com/group/XR650R Archives: http://groups.yahoo.com/group/XR650R/messages Files: http://groups.yahoo.com/group/XR650R/files For more information: http://www.angelfire.com/ut/xrlug/xr650r.html Post message: XR650R@yahoogroups.com Subscribe: XR650R-subscribe@yahoogroups.com Unsubscribe: XR650R-unsubscribe@yahoogroups.com List owner: XR650R-owner@yahoogroups.com Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.