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Topic: [HELP] Too much power using Motorshield (Read 955 times) previous topic - next topic

KernelSanders

Hello,

I am having a problem using the MotorShield (the one specified on this site) in tandem with the Arduino. I am using the Motorshield to power some dinky DC motors (2-4V). If I connect the Arduino (Uno) and Motorshield's Vin to a 9.6V, 2000mAh battery it provides way too much current to the motors (as I under the motorshield does not regulate voltage at all). However, if I say, power the Arduino with USB (Vin's are untied) and the motorshield with a voltage divided 3.5 V, the motors do not work.

I am relatively inexperienced and am sure it is an easy fix, but for the life of me I can't seem to find it. I don't think the voltage divider should be sucking that much current off the battery. Any help or insight would be appreciated. Thanks!

RuggedCircuits

You can't use a voltage divider to power motors. You will just lose too much power in the voltage divider resistors.

The right approach is to go back to your 9.6V battery and control the current delivered to your motors using PWM (pulse-width modulation).

Here's a tutorial:

http://www.arduino.cc/en/Tutorial/PWM

--
The Rugged Motor Driver: two H-bridges, more power than an L298, fully protected

Grumpy_Mike

Quote
The right approach is to go back to your 9.6V battery and control the current delivered to your motors using PWM


True, but here are some other approaches that might work:-

1) Put a resistor in series with the motor, the value should be roughly the same as the coil resistance. Work out the power dissipated in the resistor to get wattage of the resistor correct.

2) Add a voltage regulator to the battery to match the voltage you want to run the motors at and power the shield from that.

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