n-c alternator modifications: discussion and testing

[machten]

Bill,

Might be a transposition error in the V A/C of this one

5ohm, 3450rpm, 4a, 17.7vac, 20.2vdc, 80.8w

Kev

[machten]

And here's one graph of that data...



Kev

[DewCatTea-Bob]

By: wecory...
" Through all the testing the stator never got more than 15 degrees f above ambient. "

____ I'd bet that if you ran the 1-ohm for an extended period, you'd then find the stator fairly hot to the touch.


" Grand series, 6 coil.

1ohm, 3450rpm, 4.9a, 8.1vac, 5vdc, 24.5w
2ohm, 3450rpm, 4.7a, 13vac, 9.6vdc, 45.1w
3ohm, 3450rpm, 4.5a, 17.7vac, 13.7vdc, 61.7w
4ohm, 3450rpm, 4.3a, 21.4vac, 17.1vdc, 73.5w
5ohm, 3450rpm, 4a, 17.7vac, 20.2vdc, 80.8w
6ohm, 3450rpm, 3.8a, 27.9vac, 23vdc, 87.2w
7ohm, 3450rpm, 3.6a, 30.2vac, 25.1vdc, 90.4w
8ohm, 3450rpm, 3.4a, 32.4vac, 27.1vdc, 92.1
10ohm, 3450rpm, 3a, 36vac, 30.4vdc, 91.2w
11ohm, 3450rpm, 2.9a, 37.3vac, 31.6vdc, 91.6w

1ohm, 6krpm, 5.1a, 8.3vac, 5.2vdc, 26.5w
2ohm, 6krpm, 5a, 13.9vac, 10.3vdc, 51.5w
3ohm, 6krpm, 5a, 19.3vac, 15.1vdc, 75.5w
4ohm, 6krpm, 4.8a, 24vac, 19.4vdc, 93.1w
5ohm, 6krpm, 4.7a, 28.8vac, 23.6vdc, 110.9w
6ohm, 6krpm, 4.6a, 33.1vac, 27.6vdc, 127w
7ohm, 6krpm, 4.4a, 36.8vac, 31vdc, 136.4w
8ohm, 6krpm, 4.3a, 40.5vac, 34.3vdc, 147.5w
10ohm, 6krpm, 4a, 47.1vac, 40.3vdc, 161.2w
11ohm, 6krpm, 3.9a, 50.1vac, 43.1vdc, 168.1w
14ohm, 6krpm, 3.5a, 57.3vac, 49.5vdc, 173.3w "

____ This new testing-outcome seems as overwhelming as the previous was underwhelming.
__ The progression of the result-figures indicate that the maximum power-output has-not yet been reviewed. _ So it seems that still higher load-resistances (thus smaller power-demands), still need to be tested-out, so as to determine MAX.power, and, find the working-impedance of the alt.winding's power-circuit.
So how about trying load-resistance jumps between 3 to 5-ohms (per jump, starting at about 16-ohm, @ 6k-RPM), until you begin noting definite wattage-DECREASES (as load-resistance continues to be increased) ?

____ I'm hoping to get Mike's latest thoughts as to why the load-resistance has to be so high, in order to obtain the maximum wattage-output !?


Amazed-Cheers,
-Bob

[Bevel bob]

What I am looking for is a system to provide enough power to allow decent lighting and electronic ignition and balance the load at at say 3ooo rpm , dont really want more power generated and wasted as we dont have an excess of that.Its possible that I'm pretty close to that anyway with my simple and cheap system ,hope to give you a bit more usefull input soon.If switching helps to make the system more responsive and less wastefull I'm all for that too.Just wish i could follow better what you guys are doing!!.

[ecurbruce]

Kev,
Glad to see you're still following... I like the graph. I like seeing things in that format.I wonder if you could add (superimpose) the amperage readings to that graph? Anyway good work!

Bill,
Awesome! work, I'm excited(again).

Here's an article that puts it in perspective for the untrained eye. http://www.electricitycentral.com/artic ... nships.htm Be sure to look at the link within that article that takes you to the "bicycle wheel analogy".

Bruce.

[machten]

Kev,
Glad to see you're still following... I like the graph. I like seeing things in that format.I wonder if you could add (superimpose) the amperage readings to that graph? Anyway good work!

Bruce, if you're using the word "following" loosely.....well, I'm reading, anyway. Hopefully my meagre contribution to this thread below is what you were asking for. I can at least work Excel reasonably well!

Kev



I plotted this just out of interest to see the relationship. I called it "rectification efficiency" which is the relationship between A/C and D/C vs "load". I put in an assumed value of 24.8 for what I thought was a typo from Bill pointed out earlier.

[wcorey]

Nice graphs Kev, not sure if you know what you're getting caught up in...

Keep this up Bob and I'm going to run out of resistors, I don't think my decade box is up to the task, wattage wise...

Revised figure on 14 ohm, not sure what happened with the last one.
9 ohm is to fill in the annoying blank...

Grand series, 6 coil.

9ohm, 6krpm, 4.1a, 44vac, 37.4vdc, 153.34w
14ohm, 6krpm, 3.6a, 54.8vac, 47.1vdc, 169.6w
15ohm, 6krpm, 3.5a, 57vac, 49.3vdc, 172.6w
16ohm, 6krpm, 3.3a, 61vac, 52.6vdc, 173.6w
17ohm, 6krpm, 3.2a, 62.5vac, 54.2vdc, 173.4w
18ohm, 6krpm, 3.1a, 63.8vac, 55.4vdc, 171.7w
20ohm, 6krpm, 2.9a, 67vac, 58.2vdc, 168.8w
50ohm, 6krpm, 1.4a, 80vac, 72vdc, 100.8w



I have no clue really but my my seat 'o the pants reasoning tells me that (at lower rpm's) all this still isn't going to light my 55w headlight and charge my 12v battery, WTF...


Bill

[Bevel bob]

The only way i can contribute to this thread is to fix up an ampmeter and a voltmeter to my bike and run the motor at various revs with a 35 and 55watt hl bulb fitted,I'll try to do this soon.

[DewCatTea-Bob]

The only way i can contribute to this thread is to fix up an ampmeter and a voltmeter to my bike and run the motor at various revs with a 35 and 55watt hl bulb fitted,I'll try to do this soon.

____ This method is the only way I've ever done such testing of my own ! _ It works fine except ya can't be real sure of the exact RPM you're testing at (with either stock or electronic-type tachs) !

[DewCatTea-Bob]

By: wcorey...
" Keep this up Bob and I'm going to run out of resistors, I don't think my decade box is up to the task, wattage wise... "

____ Fortunately you've now reached the point of regular load-to-power-consumption ratios.


" Revised figure on 14 ohm, not sure what happened with the last one. "

____ I thought you had done each of the past reported ohm-value tests twice ?
Could it be possible that the stator was at a different temperature between then & your latest trial ?


____ Below, I've combined both of Bill's test-sessions so that the notable progression can be seen as the impedance of the alt.power-circuit becomes closer matched to that of the test-load.
Note that 'impedance-matching' occurs very near the 16-ohm point.

__ Grand/straight-series, 6 coil. 6krpm .....
1ohm, 5.1a, 8.3vac, 5.2vdc, 26.5w
2ohm, 5a, 13.9vac, 10.3vdc, 51.5w
3ohm, 5a, 19.3vac, 15.1vdc, 75.5w
4ohm, 4.8a, 24vac, 19.4vdc, 93.1w
5ohm, 4.7a, 28.8vac, 23.6vdc, 110.9w
6ohm, 4.6a, 33.1vac, 27.6vdc, 127w
7ohm, 4.4a, 36.8vac, 31vdc, 136.4w
8ohm, 4.3a, 40.5vac, 34.3vdc, 147.5w
9ohm, 4.1a, 44vac, 37.4vdc, 153.34w
10ohm, 4a, 47.1vac, 40.3vdc, 161.2w
11ohm, 3.9a, 50.1vac, 43.1vdc, 168.1w
14ohm, 3.6a, 54.8vac, 47.1vdc, 169.6w _ (1st-try... 3.5a, 57.3vac, 49.5vdc, 173.3w)
15ohm, 3.5a, 57vac, 49.3vdc, 172.6w
16ohm, 3.3a, 61vac, 52.6vdc, 173.6w
17ohm, 3.2a, 62.5vac, 54.2vdc, 173.4w
18ohm, 3.1a, 63.8vac, 55.4vdc, 171.7w
20ohm, 2.9a, 67vac, 58.2vdc, 168.8w
50ohm, 1.4a, 80vac, 72vdc, 100.8w

__ The end-outcome of this testing indicates that the maximum power-output of the tested series-arrangement is 173.6-watts with a 16-ohm load. _ And so for a load-system with at least 16-ohms total-load, this particular series-arrangement would be as efficient as possible at transferring max.power to the load (without undue energy loss).
However for our likely needs, this resulting impedance (due to the 'straight' & continuous/single stator-winding), is too high for efficient power-transfer into the intended load (just ITSELF) ! _ So if this particular stator-arrangement is circuited with a much lower working-load, then the stator-winding itself will become as part of the total-load and therefore waste much of it's own produced power & thus get hotter (than if powering a 'matched-load').
__ So I believe that if this 'straight' stator-winding would be divided in two and operated in parallel, it's total impedance would then become just 4-ohms and thus also more closely 'matched' to a likely intended load-system !
Being more closely matched means that produced-power will be more efficiently transferred INTO just the LOAD-system, and thus sparing the alt.winding itself from having to dissipate -(waste!) energy (as heat). _ (This real-life effect can be realized by studying/comparing all the test-outcome result-figures which Bill has [so fortunately!] supplied for us.)


" I have no clue really but my my seat 'o the pants reasoning tells me that (at lower rpm's) all this still isn't going to light my 55w headlight and charge my 12v battery, "

____ Well with this particular "grand" / 'straight' series stator-winding arrangement, even your 3-ohm results look promising to keep a fairly balanced system.
But I'm more sure that a parallel version will match/work better with whatever your actual load-system's total-resistance turns-out to be.
Your impressive test-results indicate that the alternator is capable of over 170-watts, we just need to move merely half that amount down into the range of your intended load-system's total power-demand.
(A guestimate of what your load-system's total-resistance might be, is down near 2-ohms.)

____ Is everyone ready for trying a parallel-version, or at least just one-half of the existing 'straight' stator-winding ?


Hopeful-Cheers,
-Bob