| Author | Message | ||
     Posplayr |
In looking at ways to reduce the magnetic strength of the rotor for the 09 setup (it has been discussed here a few times), I came on the idea of another was of reducing the magnetic flux than modifying the magnets on the rotor. There is a flux path through the stator laminations and this is probably the primary contributor to the saturation effect that limits the total power output. So conceptually at least making the lamination stack smaller should reduce the generators ability to support current. I spoke with Greg at Custom Rewind. We discussed the problems with the 09 stators and what he had been doing to rewind them including increasing the wire size. I mentioned to him that possibility of reducing the stack size and he said that is certainly something he could do. His main problem is that HD confiscate all of the old stators when they do a warranty replacement. So this is kinda experimental, but if someone is still having burned stator issues with the 09 after the rewinding, taking off 10% of the stack might provide a little more breathing room. Just throwing that out there. I would prefer to see some actual measurements of current flow in the stator, but baring that taking a little (10%) of the top of the stator if probably safe. (Message edited by posplayr on August 05, 2011) | ||
| Reepicheep |
I was thinking about that also PopSlayer... what about just drilling a hole in the lamination stack? would that accomplish the same thing, but without taking the actual stator apart? | ||
| Posplayr |
reepicheep - not sure about that, yes you cut down on the flux paths but not sure about the effect on the saturation effects. I guess you could always try, however if you are going to do that I would figure out a way of actually measuring the stator current using a shunt R/R. That will tell you if there is a drop capability. | ||
| Dannybuell |
Is this stack you speak of the 12 pole framework a series of plates where you can peel off a layer to reduce the current generated? | ||
| Posplayr |
Dannybuell - The portion of the stator that is left after you take off all the windings are the laminations. They are tightly riveted together. They are manufactured this way to "channel" the magnetic flux and avoid what are called "eddy currents" (magnetic) that just waste power. Basically there are magnetic paths in the generator that are a direct consequence of the electrical current paths. (see Maxwell's equations). Anyway reducing the capacity to carry that magnetic flux will reduce the capacity to generate output. I still have a nagging suspicion that this might be mostly an oiling problem. Sure the currents are high 40+ amps, and there is a larger output required for the 09 v.s. the 08 . It would be very telling if someone took a new stator that had a SERIES R/R connected (compufire or CycleElectric) and had that burn up. That says there is just not enough cooling to provide the power demand required. So trying to reduce the power output will simply starve the bikes electrical system from what the demand is. | ||
| 1_mike |
Grinding the stators diameter some amount would accomplish the same thing, bit with a lot less work. This gets the stator farther away from the magnets..equals less power made. And when I say grinding...I don't mean with a disc grinder..! Mike | ||
| Posplayr |
1_mike you dont want to mess with the air gap | ||
| Brumbear |
I like it , You can't bring Moses to the mtn then bring the mtn to Moses. On the oiling issue IDK the 08 are fine is there a difference in oil flow ? Is it the size of the stator in the 09 restricting flow? IDK Wish I did? | ||
| Blake |
It's been stated here on BadWeB somewhere that the 1190 resolved the issue through use of some kind of added oil cooling scheme, a stator cooling oil jet if I recall correctly. | ||
| Jdugger |
One of the things I don't understand in all of this is why I haven't smoked a ton of stators racing. If what several EEs here have said is true, since I run basically no accessories, lights or other electrical demand, I should be shunting a ton of power and making either the regulator or the stator extra hot. But, I'm already way outside the curve on both in terms of service life... This one never has resolved in my head. | ||
| Hughlysses |
Jim- that's one thing that never made sense to me either- that the stator is more likely to burn up at low RPM rather than high RPM. I get that you get more oil flow at high RPM, but you get more power (and therefore more heat) generated too. Seems like the two would at least cancel each other out so that it would be no more likely to fail at low RPM than high RPM. | ||
| Zac4mac |
The rpm you average, Jim, most likely is beyond the saturation point of the magnetics(output max) but with a much higher oil flow rate(better cooling) than most. I think you are right about how to ride the bike and make the stator last, but it is not feasible/possible on the street. I'm happy I can ride my 08 much like I do my XB12X but with a lot more headroom in rpm. If you bought an 09 or 10 1125 at fire sale price, spend a grand on 08 stator/rotor. Still less than the $13.3k I paid for Loretta up front. Z | ||
| Brumbear |
You have the answer Zac thats for sure. However I am looking for a way to have the 08 spec stuff available for years to come and perhaps knock off the cost of the new set up. I think it's doable if it isn't we still got the 08 route for now  | ||
| Blake |
One of the things I don't understand in all of this is why I haven't smoked a ton of stators racing. If what several EEs here have said is true, since I run basically no accessories, lights or other electrical demand, I should be shunting a ton of power and making either the regulator or the stator extra hot. On the track the high heat output from the stator is obviously radiating forwards and causing the front brake to get really hot. | ||
| Avc8130 |
Blake, That ^^^^ is HILARIOUS!  ac | ||
| Jdugger |
> On the track the high heat output from the stator is obviously > radiating forwards and causing the front brake to get really hot. Perhaps. And, maybe that's the same force powering your pneumatic keyboard?  | ||
| Eece_ret |
"In looking at ways to reduce the magnetic strength of the rotor for the 09 setup (it has been discussed here a few times), I came on the idea of another was of reducing the magnetic flux than modifying the magnets on the rotor." "Seems like the two would at least cancel each other out so that it would be no more likely to fail at low RPM than high RPM." I'm not sure if I agree with these statements. If you can please humor me for a moment... Let look at some basic electrical properties... W = V * I V = I*R I = k*d^(3/2) (Preece's equation for fusing point of a wire) W = Watts generated by the Stator. V = Volts, directly proportional to engine (stator) RPM d = diameter of wire (in cm) k = fusing constant. For Cu = 2530 I = Current (Amps) R = Resistance. Sum of Ohm's per foot (length * ohm/foot, yields Ohms). Varies on material (Cu, Al etc) and temp (temp goes up R goes up) Lets put it all together. At a given demand (Watts), if V goes down then I MUST go up to meet said demand. At high RPM the Voltage in the stator is high, thus for the Watts generated the Amperage is low. When at a lower RPM the Voltage goes low thus Amperage goes high. Notice how the fusing point of the wire has nothing to do with Voltage. Rather it is based on amperage, diameter of wire, and a constant derived from what the wire is made of. Here is where I believe we are falling apart. The demand from the bike, from the fans, lights, fuel system, etc outpaces the capacity of the stator. Not in watts but in Amps! The stator can deliver the Watts but when the RPM drops the stator flows so many amps the Cu wire in the stator pops like a fuse. Possible solutions: 1: Increase the diameter of the wire in the stator to cope with the amperage. 2: Increase the voltage created by the stator at lower RPM. This would require work on the rotor magnets (stronger fixed field source) and/or increase the number of windings on the poles (imagine this would be difficult due to space limitations.. ie no room for extra windings) 3: Use a material other than Cu (something with a higher k value). I am no material science guy so I am not sure what would fit the bill here, but it seems the least likely solution but thought I would mention it. I am also doubtful that using a series R/R alone could solve this issue. As far as I can tell at LOW RPM with Fans blazing, etc, the shunt reg does not seem to be shedding any "extra" energy. With a good stator at LOW RPM one will see the voltage drop quite a bit, this tells me all the power coming form the stator is all going to the bike (fans, lights etc...), thus a series reg should place the same demand on the stator at low RPM (unless the series reg is much, MUCH more efficient. Then the load on the Stator would be lessened and some gains might be seen) I feel that a STRONGER Stator, both in ampacity (accomplished via wire gauge) and wattage (accomplished by increased AC voltage) coupled with a series reg (decrease load (ie amperage) when available output is greater than demand) will cure this issue once and for all. That or go with an 08 setup... (Message edited by eece_ret on August 09, 2011) (Message edited by eece_ret on August 09, 2011) | ||
| Eece_ret |
Posplayer.. "So conceptually at least making the lamination stack smaller should reduce the generators ability to support current. " By decreasing the thickness of the lamination stack could one increase both diameter of the wire as well as number of windings/pole. The targeted effect would be higher voltage at low RPM but a lower saturation RPM (so those extra windings don't Chernobyl the VR at high RPM) (Message edited by eece_ret on August 09, 2011) | ||
| Dannybuell |
Eece_ret - what percentage of stack removal would you suggest? | ||
| Eece_ret |
Dannybuell - not sure, need to know more about the current setup... Essentially though it comes down to the math of building a stator, how many windings around how many lamination's would yield a voltage/wattage envelope which would suit our needs. |
