Arduino Rover - Voltage dropping

Hello,

I want to build an Arduino-powered rover, but I'm having issues with the power supply. I'm using two motors that run off 3V, and a 5V Arduino Pro Mini. For the power supply, I have a 2-cell Li-ion battery which is at 7.4V.

The Arduino Pro Mini has a built-in voltage regulator, but I'm not sure how to drop the voltage to 3V so I can power the motors safely. The motors are driven by a L293N motor driver.

Please advise?

The output of an Arduino voltage regulator cannot be used to power motors.

Can you provide more details about the motors? The phrase "3V motors" suggests cheap toy motors, which are intended to run directly from a couple of AA or D cells. If so, you may have a hard time mounting and controlling them, as such low voltage motors often require more current that an L293N can handle.

jremington: The output of an Arduino voltage regulator cannot be used to power motors.

Can you provide more details about the motors? The phrase "3V motors" suggests cheap toy motors, which are intended to run directly from a couple of AA or D cells. If so, you may have a hard time mounting and controlling them, as such low voltage motors often require more current that an L293N can handle.

It is not my intention to use the Arduino directly to power the motors. It's just for comparison.

The motors in question are FA-130RA-18100. Datasheet: http://www.pololu.com/file/download/fa_130ra.pdf?file_id=0J11. Here's the driver: http://www.hotmcu.com/motor-driver-2a-dual-l298-hbridge-p-45.html

The L293N cannot handle the stall current (2 amps) for those motors and they will draw that briefly each time they start up. It is just barely able to handle the running current (about 600 mA) at 12000 rpm, the point of maximum efficiency. Otherwise, it might work OK as the driver itself will drop around 3 V internally. If the driver overheats, it will shut down.

You might consider small metal gearmotors with convenient mountings like these http://www.pololu.com/category/60/micro-metal-gearmotors

I'm using a Tamiya Twin-motor gearbox, so I might have to look into a high voltage low current motor. Are there any other [u]cheap[/u] drivers that could handle a bit more like 4A?

It would be hard to beat this: http://www.pololu.com/product/2130