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Solarbotics motor question

My robot is going to compete in a competition that will require it to compete in different competitions.  For one competition, it has to be very efficient, and basically keep following a black line longer than everyone else.  Another competition that it has to compete in is a tug of war.  The rule is, it cannot change its hardware in between competitions.  Naturally, for the endurance competition, you want to hook up a smaller voltage to the motor.  But I was thinking of using the following circuit in order to give the motor more voltage for the tug of war competition:

 tugofwar.jpg

It is actually a simplified circuit.  There really is a microcontroller and h-bridge in there, but this schematic should give everyone an idea of what I'm trying to do.  In endurance mode, the robot will run off of the 3.3V regulator.  But for the tug of war, the relay will kick in and give the motor 9V.  The diode will keep the 9V battery from shorting directly to the 3.3V regulator.  We plan on using the 5V solarbotics motors. 

And now, we finally get to my question.  My question is...Has anyone ever ran those solarbotics motors at a voltage higher than 5V?  And if so, how long did they last?  I've done a similar scheme with huge motors for my solar boat.  They were 24V motors, and they were able to withstand 36V across them.  But I am unsure about the quality of the solarbotics motors.  Thanks in advance for any info anyone can give me.

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 The short answer is maybe...

The motors are so cheap that I recommend you buy one and try. Add some load to the motor, so it doesnt spin free, and hook up a 9volt battery and let it run until one of them dies. either the motor or the battery.

I dont know which of the solarbotic motors you plan to use, but several of them use motors with a standarized shape and size. So it should be possible to find different replacement motors with other voltage and load capasities...

 

/ vzz-clck-"Maneuver"

Yeah, that's probably what I'll do.  Thanks for the idea.

 

Gabe

If these are those standard little motors found everywhere, they won't last too long with 9 volts. I did a lot of testing a while ago on different voltages with these motors, at 9v they tend to run so fast they scream. They also get extremely hot, and will probably melt their windings pretty soon.

 Also, you may want to look for voltage regulators with an enable pin, that way you can run two in parallel and enable them with the microcontroller.

Wow, I didn't know there were regulators with enable pins.  Thanks for the tip!

 

Also...I figured they wouldn't last very long.  I'm hoping they'll last long enough for the competition though.  Compared to our robot, all the other robots look prett big, so we need a way to be competitive in the tug of war.  I think we have the endurance in the bag though..

 

Gabe