Voelker:
Does you H-bridge gets hot ? Some H-bridge include an over-temperature protection that make it shutdown unti it cools down. If it is the case you should consider changing the h-bridge for a more powerfull one and/or stick and heatsink on it. Try measuring the current that flow through the motor at high-speed when blocking the wheel.
Voelker, thank you very much for your speedy response!
From spark fun product page "the SN754410 can drive 4.5V up to 36V at 1A continuous output current! " http://www.sparkfun.com/commerce/produc … cts_id=315
I am surprised that overheating could be the problem because the voltage is only 5V. I do not know what the current is though. I will try measuring it when I get home from work.
I did a quick google search and found an article which stated that “In order to get the full 1Amp you will need to add a dip heat sink”. The article also mentioned that the SN754410 has “Thermal Shutdown” as you suggested.
Thanks again for your response, it was very helpful. Hopefully adding a heatsink will solve the problem. I would purchase a more powerful H bridge, but I haven’t seen one on Sparkfun that isn’t way more money. I know that you suggested taking the old motor controller out of the car, but that is a little bit out of my experience range.