I have a question about powering a v.1 DK Electronics motor shield. At the moment I am currently using either two or four 3-6v motors and struggling to get a stable speed across all motors.
I have read the manual for the v.1 shield written by LadyAda and noticed she said not to bother using a 9v battery to power the shield as it would not be sufficient.
I have used a 9v battery to power 2 motors, so far with no problems--the motors spin fine, but when connecting the shield to a 12v supply, the motors behave erratically. I have noticed with 12v the speed needs to be kept under a certain level to control the voltage and have even used PWM with the delay function and cannot get a stable speed. One strange thing I noticed is that if I touch one of the motors or turn it on an angle, the motor slows right down and sometimes stops, almost like I’m changing the magnetic field or affecting the torque. Also (on the 12v supply) the motors slow down after about 10 seconds, sometimes coming to a halt. I can't seem to find a speed/voltage range that works correctly with 12 volts.
When I try and connect 4 motors with a 9v supply, not much happens. Two motors spin fast, one spins slow and the other is stalling. If I try and connect 4 motors to a 12v supply, the behaviour is just as erratic as if I had two connected. Really struggling to understand what's going on here.
(I am also powering the Arduino separately through USB connection, as advised)
Could anyone possibly advise me as to how to correctly use a 12v supply with a motor shield and where I may be going wrong? It generally seems the 12v is too much, but I was under the impression the voltage is regulated and the system could handle 24v or so. The bridge gets very hot very quickly, also. All I can think of is that I'm using the 'wrong' motors, but I presume there would be some way of getting them to work correctly.
To simplify: 2 motors is okay with 9v. 4 motors won't work with 9v. Nothing works correctly with 12v.
Thanks in advance!
PS. Sorry for the school boy questions, I’m genuinely stuck and cannot find the material to explain.