RC Technology

Old 03-13-2007, 07:33 PM
  #46  
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Pason, is the working prinicple of an engine dyno similar to a electric motor dyno? RC Electric motor's dyno usually works on calculation by spinning a fixed mass. For Gas engine, what does it use? What type of Load cells? I remember you posted somewhere before rite?
Nipple,

Basically the eddy current dyno is similar to our brush motor.
If you remember Tekin dyno introduced >10yrs ago or Competition electronics,
they make use of a secondary motor to measure the Test motor.

Base on the rpm and current/voltage induced, they are able to give you a quite accurate data.

If you need a fixed mass dyno for DC motor, I can lend you my Fantom motor dyno.

There is also a special rotating torque sensor which the sensor rotate together with your motor...but the price is around $5~10k per sensor....crazy price.
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Old 03-14-2007, 12:30 AM
  #47  
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Originally Posted by SuPerDraGon
Nipple,

For cell voltage measurment, you do not need a high sampling rate A/D card.
Maybe I can try to borrow one from NI...do you know how to use Labview program? Maybe next year I can showcase your work during NI days.
I dun need the high sampling rate but rather higher bit for better resolution.
My current PicoTech datalogger is only 10bits, only giving me 5mv resolution. With a 12bits card, at least I can get 1.5mV resolution.

That are many other factors that why I'm not using a ADC with MicroController. Such as calibration and software interface. Eg. I'm using thermistor and it is non linear thus requiring a conversion table from manufacturer for better accuracy. Standard calculation is not very accurate. Although LM35 IC Temp sensor (Same as the one commonly found in our chargers such as Much More CTX) give linear and proportional voltage, but the thermal response is slow. And with the high dT/dt of the batt at the end of charge, the batt may be already over 50degrees but charger only show 45degrees.

RTD is quite expensive and thermocouple is not easy to setup to get accurate measurement as the lead wire itself will affect the measurement.

I only know basic LabView functions. Currently using Picolog and Picoscope.

BTW, what's this NIdays har? I always receive the email but never bother to read.


Last edited by Nipple; 03-15-2007 at 05:59 AM.
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Old 03-14-2007, 06:11 AM
  #48  
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Sample graphs of my tests.

Data are recorded using Picolog and exported to excel for analysis and presentation.
Attached Thumbnails RC Technology-sample-plw-graph.jpg   RC Technology-charge-graph.jpg   RC Technology-discharge-graph.jpg  
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Old 03-14-2007, 08:46 AM
  #49  
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Originally Posted by SuPerDraGon
Nipple,

Basically the eddy current dyno is similar to our brush motor. If you remember Tekin dyno introduced >10yrs ago or Competition electronics,
they make use of a secondary motor to measure the Test motor.

Base on the rpm and current/voltage induced, they are able to give you a quite accurate data.

If you need a fixed mass dyno for DC motor, I can lend you my Fantom motor dyno.
I think the eddy current used in "proper dyno" is to generate electromagnetic braking thus creating the load. Then also got hydraulic braking ones rite?
CE's turbo dyno measure actual torque from load cell.

But the Tekin one.........also got slave motor as load. But it's power measurement I think is based on p=vi.
then power in - power loss = power out.
then from power = torque x angular velocity to determine torque.

So when slave motor condition changed, the calulated power also change despite the test motor's performance is constant.
Can find pple selling Tekin ones on ebay....but I'm not very interested.....

Correct me if I wrong.



BTW, why u buy fantom one, don't buy robitronic one?
Alvin Yap (Not the Alvin Yap playing F103 now) bought one from Wui Kiat last time, dunno if he still has it with him......

Last edited by Nipple; 03-14-2007 at 09:23 AM.
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Old 03-14-2007, 06:30 PM
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Nice graphs.

Can't wait to see your full write up.
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