Hello everybdy! I used adafruit motor shield to control my RC car, but my car moved very slowly. That's why I tested to wire my battery to my RC cars motor and it moved very much faster than with motor shield. So why motor shield makes my RC car slower?
So why motor shield makes my RC car slower?
May be due to voltage drop across the motor controller.
zoomkat:
So why motor shield makes my RC car slower?
May be due to voltage drop across the motor controller.
agree.
The IC at Adafruit motor shield L293D uses BiPolar transistors which will have some Voltage drop at higher current draw ( RC cars motor). Look at the Vcesat specs in the L293 data sheet. With 1Amp of current the High side transistor's will drop ~1.35V and the lower side ~1.2V or 2.55V total. if you use 7.2V battery then motor will left 4.65V.
To have less Voltage drop use an H-bridge that has power MOSFETs with a low Rds-on spec.
I list few H-Bridges with low voltage drop here;-
http://forum.arduino.cc/index.php?topic=169717.msg1262646#msg1262646