Calculate Dynamo Max Power Output

AI Thread Summary
To calculate the theoretical maximum power output of a small DC dynamo, one can use the formula P=V^2/R, where V is the measured voltage. To determine R, the internal resistance of the dynamo should be calculated, as it is crucial for applying the maximum power theorem. An alternative approach is to use P=IV and graph current (I) against various external load resistances to find optimal performance. Caution is advised, as very low resistance can lead to excessive current and potential damage to the dynamo. Ultimately, measuring the current in the circuit will help in obtaining a single conversion factor to kilowatt-hours.
El_Guapo
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Hi,
I have a small DC dynamo (with no spec sheet) which i digitally sample to find it's voltage at any given time. I want to display theoretical max power output, how can I calculate this?

Can I use P=V^2/R where V is measured. How do I calculate R? I read a wikipedia article which says to calculate the ac resistance of the dynamo and take the load as equal to internal resistance of the generator (max power theorem.) Will this work...I'm not too sure what I'm doing on this one. Thanks.
 
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El_Guapo said:
Hi,

Can I use P=V^2/R where V is measured.

I would use P=IV, and graph IV vs. various loads (external resistors). But be aware that very low (or no) resistance could result in very high current outputs, and might "fry" your dynamo.
 
But I know the maximum power will occur when the load resistance is equal to the internal resistance so I guess I could just measure the current flowing in this circuit. I'm just after a single number to act as a conversion factor to kw/h.
 

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