Over 100 Watts

[willib]

i crossed the 100W barrier

My little mini Gen II output 133.3 watts today!

the voltage across the output was 12.3V

the current was 10.84A

this was into a 6 Volt , 6.5 A/H sealed Lead-Calcium battery

this is a diagram of the circuit

my meter was  reading 2.71V across the .25 ohm shunt ,which is four 1 ohm (10 watt) resistors in parallel.

i might try Ron's , one foot of #10 wire shunt method , because at 10.84 Amps  into the 1/4 ohm resistor , is 28 watts wasted just in the resistors.

the excercise bike continues to be a great source of fun , and a way to stay fit , before i take it off the excercise bike and put the large blades on there i would like to completely define it.

volts current RPM , should be interesting ?

[s4w2099]

Do you have any idea on the alternator's RPM?

[Jerry]

Hi Willib.

Welcome to the 100+ watt club. How did you draw that schimatic? Its nice I like that.

                      JK TAS Jerry

[hiker]

no dout your thinkin on a 1000 watts now--youve got the bug...........

hey  JERRY  did you make up your mind what your going to do with those big ceramics??

you left us hangin back there :}

had to ask there WILLIB..hope you don"t mind............

[willib]

yes 51 to 52Hz

thats 51(60)/8 = 382 to 390 RPM

HZ times 60 divided by half the number of poles

[Jerry]

Hi Hiker.

No Idea yet. If I leave them in tact the thing could get very large and heavy.

Problem is since there ceramics even large and heavy won't make much power.

I hate to waiste a set of large steel discs and end up with not much power.

No hurry on these ceramics, an idea will come along some day. Maybe the right parts will surface in the daily stride of things?

                        JK TAS Jerry

[willib]

i used linear technology " swCad III

http://www.linear.com/designtools/software/switchercad.jsp

it is more of a circuit analysis program , but makes nice schematics also.

a word of caution though , it is not as intuitive as eMachineshop , as programs go..

but if you decide you want to try it out , i can help..

[willib]

i just finished the graphs you see below , and i am very impressed with the look of them

the Minigen II is more powerfull than i had thought.

the load is a huge honking 0.5 Ohm resistor 100 Watt  1% with a built in heat sink

a batterys voltage will change during testing , so i used the resistor instead

i would have preferred a battery since it is relatively easier to pedal , but the resistor gave me no break at all and i was pretty worn out by the time i got to 106 Watts at 368 RPM.

I used a video camera and a VCR to record the readings from the meters , i used two voltmeters across the resistor , and averaged the volt reading ,

The RPM reading was from one meter taken from one coil





so i was able to step through the test one frame at a time with the VCR , a pretty cool way to do it

the little triangles on the graphs are the plotted points

[willib]

I did some battery charging graphs

Current was measured with a calibrated length of 0.045" dia wire , to 0.01 ohms

i also preformed the test with two 1Farad caps (in parallel) between the Diodes and the load.





i'm not sure of the reason i was able to pedal up to 54.2Hz (407 RPM) with the caps in the circuit , but i wasnt able to go that fast without them.

It may be that the caps gave me a little assistance when i let off the pedals a little bit , and this assistance gave me the break i needed to pedal faster.

Note: i am measuring total alt output , not just current and power into the battery.

although the loss this time is just 2.05 Watts at 14.32 Amps because of the 0.01 ohm shunt.

[willib]

This test was preformed with a 12 Volt battery auto battery

i used the caps and the 0.01 Ohm shunt.

i tried to get 60 Hz but only got to 59.7, in this test the load wasnt holding me back the RPM needed to get the power was the problem

at around 2.33:1 i was pedaling pretty darn fast.

the power maxxed out for pedaling at 448rpm at 171 Watts.

[s4w2099]

is this the gen that has a 1ohm line resistance, 7/8 x 0.5 magnets, 78 turns of #17, dual rotor 16 pole?

[s4w2099]

I wonder if line resistance will deform this curve. I have a little alternator with a line resistance of 6.5 ohms and the graph doe snot seem to be that linear. Maybe the power is washing out in the coils resistance? or maybe my frequency readings are off as the RPM increase?

[willib]

Why such a high line resistance?

When i was boosting the alt output , That would mess up the RPM readings , as you can imagine.

[willib]

my graphs are good for matching the alt to a set of blades , i think. especially the 12Volt battery test.

I'm thinking a set of 6 foot dia blades should be good . because with a TSR of six at 12MPH  the blades will be going 343 RPM at an efficiency of .25 according to Warlock's calculator.

and they will be offering 61 Watts power, while the alt will try to be putting out 77 watts , into a 12 Volt battery. so not a good match..unless i want them to run stalled

But at a tsr of 5 things change

The blades will be going 285 RPM in a 12 MPH wind , and at 285 RPM the alt will be putting out 37 watts , but the blades will still be offering 61 watts.

anyway i think its a good match

does anyone know what percentage of alt output to blade output is best?

[s4w2099]

its a very little alternator with 200 turns of 20 gage. cuts at 100 RPM for 12V. Nice in low winds but sucks at higher winds. At 24V it can output 480 watts.

[willib]

I apologize , i did not see this post.

This alt is a sixteen pole 7/8" dia by 1/2" mags , 12 coils ,78 to 80 turns of 0.045" dia wire yes.

Dual 8 inch dia. rotors , yes.

the line resistance is made of a combination of #12 stranded & #18 stranded wire

i have about eighteen inches of 18 gage between the alt and the diodes ( i'm going to change to 12 gage on this later on )

32 inches of 12 gage wire between the diodes and the two one Farad caps , and twenty four inches of 12 gage wire from the caps to the battery , i'm going to use the voltage drop across one of the 12 gage strands to measure current