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Old 05-30-2013, 10:12 AM   #6141 (permalink)
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Power into the motor is approximately power out of the motor (except for losses), so...

1) BatteryCurrent * BatteryVoltage = MotorCurrent * MotorVoltage.

2) MotorVoltage = BatteryVoltage * PWM_DUTY

Let's substitute 2 into 1:

BatteryCurrent * BatteryVoltage = MotorCurrent * (BatteryVoltage * PWM_DUTY)

Now, cancel BatteryVoltage from both sides of the equation, to get....

BatteryCurrent = MotorCurrent * PWM_DUTY.

Or, said another way,
BatteryCurrent / MotorCurrent = PWM_DUTY

So, if you only know the PWM_DUTY, there are still 2 other variables. You can't know both the battery current and the motor current if you only know the pwm duty.

Hey! It has over 1 million views! I was hoping it would roll over to zero, and there'd be a y2k catastrophe. oh well.

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