I am looking for suggestions on how best to drive my Pololulu motors on my MopBot. This bot is basically a swiffer mop attached to the bot which it pushes around so it requires more torque than the usual small bot I have done before. These motors are rated 450 ma @6v with no load and 6 A stall. I am using 6 NiMH AA batteries in series for about 7.2V - 7.5V although could go higher if needed.
I have an L298 based motor shield which I tried but it loses about 3v across the shield. The motors just don't have torque to push the mop around at 4v so that is not a good option to go with. The bridge does have analog outs that gives the amperage being used which is very helpful. I could add a few more batteries and be done with it, but that is less than ideal.
I have several Dagu mini drivers which has literally no drop across it with a FET H bridge on it. According to the documentation I downloaded, these are rated 2.5 A per side. I also have some N-channel Mosfets that I bought from Adafruit to try out
http://www.adafruit.com/products/355
which are rated 60 A. Is there a way I could use these with the mini to control the motors? Or, is there a good way to monitor amperage with the mini and make sure it stays under 2.5 A? I haven't tested the motors while pushing around the mop, but I will assume for the moment that a normal load will be under 2.5a so if I could monitor amps I could save the mini from going up in smoke when the motor stalls.
I also have some relays, but those use quite a bit of power to run so not best solution either.
Suggestions? What have other folks done in similar situations?
Regards,
Bill