n-c alternator modifications: discussion and testing
Posted: Fri May 20, 2011 12:52 am
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<EDIT> August 29 2011
The content of this thread originated in the, ‘6volt or 12volt?’ thread, which has been moved to it’s own space and this one then renamed to better reflect it’s purpose.
As is typical, the material that has remained here sprouted up spontaneously as an offshoot of yet another sidetrack in the same thread, which was a discussion on the relationship between the stock 6-pole alt and the stock n-c R/R (and that one really started in yet another thread, "six coil alternator in a narrow case 250").
What’s here is a discussion of how to increase the power output of a narrow case 6-pole alternator that includes actual bench testing of various modifications of what started as a 4 coil n-c stator and progressed to various rewiring schemes, installing an additional two coils and still further to modified/adapted modern Denso alternators.
This thread consists of 350+ posts, is lacking in organization, and can be difficult to follow (I backed it up to a Word doc and at that time ended up as 523 pages, 926,825 characters).
It wasn’t really planned, it just happened, so of course has its share of mistakes, failures and dead ends, as well as revelations and successes. It was largely a group effort by DCT-Bob, ecurbruce, MotoMike and myself with occasional appearances by Bevel bob and machten. I look at this simply as an archive, other more specific and functional threads are being created to organize, continue and maybe conclude some of the topics started here. I'll add links here as those works are completed.
What follows as first post here is when I joined in to what was becoming a bit of a contentious discussion and at the time was 8 or so pages into the original thread.
I've been following this thread closely hoping to absorb at least a bit of it but unfortunately the vast majority goes way over my head. I greatly appreciate the efforts put forth to simplify things for us 'uninitiated' types but it has obviously spun out of control in that particular aspect. Every time I think I 'get it' some counterpoint comes up that confounds me yet again. It's like being a juror on a court case where each side is of course presenting a view only advantageous to their side of the argument. I would really like to jump ahead to the 'closing statements' that synopsizes each view, then have the judge explain it all to me in laymen terms, then listen to the CNN analysis.
However, the more practical 'hands on' aspects of getting the most out of the stock alternator are still within my realm of comprehension and all this has gotten me interested enough to put my test setup back in use.
I previously didn't put much effort into the stock setup as my preliminary tests were fairly disappointing compared to the results with the more modern stuff I was also playing with and my primary goal was to simply outfit my project bike with something that would run a 55w headlight. The number of threads on the subject and plethora of different possible methods were making my head spin and I never felt I got a handle on it so I basically ignored it all and started from scratch on my own terms.
The few basic numbers I previously came up with for the '60w' n-c alternator were specifically at Bob's request and I never got around to set it up again with that alternator to satisfy all his inquiries. Something I also never did was to split the output or even lift the grounded coil ends. Yet another thing I neglected was to load test the straight AC output, I always had at minimum a generic rectifier, as Bob had voiced concern that the random R/R's I was using would skew the results in an indeterminable way.
I still have things set up so as to take reasonable requests for further testing as I'm sure I'm missing some important and obvious aspects...
I don't have a stock R/R so that still isn't an option but I do have many others, from generic rectifier blocks and zener's to 3 ph mosfet R/R's and many things between.
Well anyway, I've some new numbers and they leave me scratching my head a bit.
Not sure how simply grounding/ungrounding the ends would have any affect but it seems to be part of the discussion so I've tried it and included it in the results. I can also take current readings if needed.
Output readings straight off the stator at 3450 RPM, n-c '60w' 4 coil stator, 6 pole rotor. Hopefully I got my numbers right, I never seem to think to write things down, lol.
AC output, no load, stock 'two wire' setup with ends grounded; 31.6vac
AC output, no load, stock 'two wire' setup with ends ungrounded; 31.6vac
AC output, load=55w headlight, stock 'two wire' setup with ends ungrounded; 11.6vac
AC output '4 wire setup' (coil ground ends lifted and separated with wires running out), no load; 15.8vac (connecting meter to either individual 'side' (or pair of wires))
AC output '4 wire setup' (coil ground ends lifted and separated with wires running out), load=55w headlight; 12.1vac " "
So I am appearing to get more output from each individual "separated side" than from the combined total of the two run as stock (grounded) or with the grounds connected/lifted.
If I had though I'd get this result in the beginning, it may have saved me a shitload of time/money/work playing with the new stuff, as I would likely have just used the stocker and not gone any further
I haven't yet tried them in parallel (simultaneously) with a load on each, I'll have to dig up another headlight...
Also haven't run it for any length of time and hit it with a temp gun, seems like temperature could be a good relative indicator of duty cycle for the various configurations.
Bill
<EDIT> August 29 2011
The content of this thread originated in the, ‘6volt or 12volt?’ thread, which has been moved to it’s own space and this one then renamed to better reflect it’s purpose.
As is typical, the material that has remained here sprouted up spontaneously as an offshoot of yet another sidetrack in the same thread, which was a discussion on the relationship between the stock 6-pole alt and the stock n-c R/R (and that one really started in yet another thread, "six coil alternator in a narrow case 250").
What’s here is a discussion of how to increase the power output of a narrow case 6-pole alternator that includes actual bench testing of various modifications of what started as a 4 coil n-c stator and progressed to various rewiring schemes, installing an additional two coils and still further to modified/adapted modern Denso alternators.
This thread consists of 350+ posts, is lacking in organization, and can be difficult to follow (I backed it up to a Word doc and at that time ended up as 523 pages, 926,825 characters).
It wasn’t really planned, it just happened, so of course has its share of mistakes, failures and dead ends, as well as revelations and successes. It was largely a group effort by DCT-Bob, ecurbruce, MotoMike and myself with occasional appearances by Bevel bob and machten. I look at this simply as an archive, other more specific and functional threads are being created to organize, continue and maybe conclude some of the topics started here. I'll add links here as those works are completed.
What follows as first post here is when I joined in to what was becoming a bit of a contentious discussion and at the time was 8 or so pages into the original thread.
I've been following this thread closely hoping to absorb at least a bit of it but unfortunately the vast majority goes way over my head. I greatly appreciate the efforts put forth to simplify things for us 'uninitiated' types but it has obviously spun out of control in that particular aspect. Every time I think I 'get it' some counterpoint comes up that confounds me yet again. It's like being a juror on a court case where each side is of course presenting a view only advantageous to their side of the argument. I would really like to jump ahead to the 'closing statements' that synopsizes each view, then have the judge explain it all to me in laymen terms, then listen to the CNN analysis.

However, the more practical 'hands on' aspects of getting the most out of the stock alternator are still within my realm of comprehension and all this has gotten me interested enough to put my test setup back in use.
I previously didn't put much effort into the stock setup as my preliminary tests were fairly disappointing compared to the results with the more modern stuff I was also playing with and my primary goal was to simply outfit my project bike with something that would run a 55w headlight. The number of threads on the subject and plethora of different possible methods were making my head spin and I never felt I got a handle on it so I basically ignored it all and started from scratch on my own terms.
The few basic numbers I previously came up with for the '60w' n-c alternator were specifically at Bob's request and I never got around to set it up again with that alternator to satisfy all his inquiries. Something I also never did was to split the output or even lift the grounded coil ends. Yet another thing I neglected was to load test the straight AC output, I always had at minimum a generic rectifier, as Bob had voiced concern that the random R/R's I was using would skew the results in an indeterminable way.
I still have things set up so as to take reasonable requests for further testing as I'm sure I'm missing some important and obvious aspects...
I don't have a stock R/R so that still isn't an option but I do have many others, from generic rectifier blocks and zener's to 3 ph mosfet R/R's and many things between.
Well anyway, I've some new numbers and they leave me scratching my head a bit.
Not sure how simply grounding/ungrounding the ends would have any affect but it seems to be part of the discussion so I've tried it and included it in the results. I can also take current readings if needed.
Output readings straight off the stator at 3450 RPM, n-c '60w' 4 coil stator, 6 pole rotor. Hopefully I got my numbers right, I never seem to think to write things down, lol.
AC output, no load, stock 'two wire' setup with ends grounded; 31.6vac
AC output, no load, stock 'two wire' setup with ends ungrounded; 31.6vac
AC output, load=55w headlight, stock 'two wire' setup with ends ungrounded; 11.6vac
AC output '4 wire setup' (coil ground ends lifted and separated with wires running out), no load; 15.8vac (connecting meter to either individual 'side' (or pair of wires))
AC output '4 wire setup' (coil ground ends lifted and separated with wires running out), load=55w headlight; 12.1vac " "
So I am appearing to get more output from each individual "separated side" than from the combined total of the two run as stock (grounded) or with the grounds connected/lifted.
If I had though I'd get this result in the beginning, it may have saved me a shitload of time/money/work playing with the new stuff, as I would likely have just used the stocker and not gone any further

I haven't yet tried them in parallel (simultaneously) with a load on each, I'll have to dig up another headlight...
Also haven't run it for any length of time and hit it with a temp gun, seems like temperature could be a good relative indicator of duty cycle for the various configurations.
Bill