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Originally Posted by indieFan
The questions never end, do they? ;-)
I downloaded Dr. Joe's Motor Calc spreadsheet, but in looking at the data voltage I'm a bit confused. Is this supposed to be the voltage measured during the test, or the voltage it was supposed to be? For example, I was testing the motor at what was supposed to be 6V, but it was really 4.7V. Which number should be entered?
Thanks,
indieFan
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Indie,
I will defer to Joe to correct this but it appears that the data voltage is what you would measure at the terminals of the motor under test. Since Joe's calculations are used for input electrical motor power the only correct calculation is motor terminal voltage vs. current. the fact that you were using a 6 volt battery and were reading much less is due to a discharged battery or a high current. Remember that there is some internal resistance in the battery that is electrically in series with the load. As a battery is discharged, this internal resistance goes up. More resistance limits the amount of current that can be delivered by the battery. Please remember that a battery that is not designed to supply the current needed by the motor will also show a reduction in voltage. I think it is important to note that the spreadsheet is to be used for the motors listed. I would contact Dr. Joe (PM) directly if he does not answer here just to be sure.