Jerry's dual rotor update.

[Jerry]

A few days ago I wound the 9 coils. The turn counter on the ewinding machine said 250 turns each coil.

I measure the resistance on each coil with my Fluke true RMS meter. when the meter leads are shorted the meter reads .05 ohms. I deducted .05 ohms from each coil measurment. I Had wraped the coils in 2 places to maintain there shape while waiting to be imbeded in the stator.

Here are the coils 1 through 9 and the resistance readings.

  #1 2.35 ohm.

  #2 2.39 ohm.

  #3 2.39 ohm.

  #4 2.46 ohm.

  #5 2.47 ohm.

  #6 2.44 ohm.

  #7 2.45 ohm.

  #8 2.45 ohm.

  #9 2.45 ohm.

I'm not sure what causes the res. diferance. Allthough it is slight. If these coils were wired in perelell there would be some friction between them but very slight.

could be a microscopic wire size change or the chemical makeup of the copper?

However since each coil will have its own fullwave bridge the slight diferances have no influance on compatability. They'll all get along fine no matter what there coil neighbor is doing. They'll all be contributing to the total power output without disturbance from there coworkers.

                          JK TAS Jerry

                       

[Jerry]

I ment to say I wraped the coils with cloth first aid tape. So I wrote the coil #s on each coil in ink.

                         JK TAS Jerry

                         

[wpowokal]

Capacity of the battery in you metre could explain such small differences, how you attached the probes etc.

But hey sounds good to me.

allan down under

[DanG]

Batch testing ebay solar cells I found I had to solder connections onto front PV leads to get consistent readings, never the same readings twice etc.. I bought some .999 soft silver 20awg wire and soldered the ends of three-inch pieces to the meter lead probe wires crimp connector (inside insulating sleeve) & wrap it around the alligator clip extensions when not in use, and uncoil it to suit soldering onto hard-to-measure items (like .45 volt PV output or low ohms using a standard fluke or triplet meter)

For my cell test jig I bypassed the leads all together, soldering eight-inch silver wires onto meter circuit board directly then velcro to attach meter to jig. The dead-soft annealed silver is easy work with and has yet to fatigue or kink.

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[Flux]

Jerry those resistances are well within experimental error using a multimeter.

Contact resistance and thermal emf's will prevent you doing much better at such low values.

Flux

[RP]

Jerry,

Try this:

Connect all of the coils in series and then hook them to a 12 volt battery or power supply.  The total will only draw about 0.5 amp.  Measure the voltage drop across each coil (they should be equal).  This test will be more sensitive for your meter and less sensitive to connection quality issues.

[Jerry]

Thanks RP.

I like this idea.

                       JK TAS Jerry

[RobD]

Jerry I agree with RP. The only way to get really accurate resistance measurements is with the 4 wire method combined with the ability to null the meter before each reading. My meter has gold test clips for better contact too.

The 4 wire method uses different leads for probe current and measurement and once your start to get into mOHMS it makes a big difference. The readings you got are well within specs and I'll bet if you went back and took them again you'd get slightly different readings on each coil.

RobD