Quote:
Originally Posted by Ether
What he did, I believe, is to pull the following data:
... from some 10.5 Volt motor curves that he has.
He then reasoned as follows:
- if 35 amps are supplied to each motor, they will produce the output power indicated above at the rpm's specified above (if his 10.5 motor curve data is valid, this is valid reasoning)
- the sum of the output power from each motor is then used to calculate how fast the impeller will spin, given that power
- that impeller speed is then used to calculate what the gear ratio must be for each motor in order for each motor to be spinning at its respective specified rpm when the impeller is spinning at the speed just calculated.
It's an interesting solution, but it's not the solution to the problem I had in mind because it requires that the current to each motor be controlled at 35 amps. The problem I had in mind did not involve controlling the current. As stated, each motor is being driven at a constant voltage (12V), not a constant current.
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You are correct. I use the motor curve data from here:
http://www.chiefdelphi.com/media/papers/download/2593
Indeed, I try to do my math to confirm that I will get what I need without popping breakers. In addition, I've seen even a fresh battery drop voltage when you are pulling power to the drive train: doing your calculations at 12 volts may result in a performance problem in the field. Just our experience though, perhaps others differ.