Motorsheild voltage output issue/options

Other Hardware Motors, Mechanics, Power and CNC
1

Hi all,

I'm using the official Arduino Uno and Motor shield R3.

VIN pin has been cut on the motorshield so I can power 2x DC motors from a separate power source.

(Arduino independently powered by a 9V battery.)

So on the motorsheild I have 4.5v (3x AA batteries) voltage in, however this is only producing around 2.5v out to motors.

Does this sound about right? I've read that the shield will absorb some of the voltage. What would be the best option for powering the motors? Add more AAs? or maybe theres another type of battery I should use?

Thanks for any advice!

2

Firstly you must provide at least 5V to the motorshield motor supply or else the 5V logic supply will try to drive the motor through internal paths in the driver chip.

Secondly the L298 drops about 2 to 2.5V from its motor supply across the darlington output stages, so your
motor supply needs to be 2.5V more than the motor rating.

3

Thanks, that explains a lot!

Is there a good battery that would take roughly the same space as the AA's but supply say 7Volts? I'm not sure what to look for.