L293D 9V Step Down?

Hello,

I have built a fully kitted out car just to find out that its slightly too heavy. I am powering my arduino off 9V battery, and the L239D off of three 1.5V AA batteries providing 4.5V to the EXT_PWR. My easiest solution is to reduce weight, mainly the batteries. If I used a single 9V battery into the L239D, would it step down the voltage to 4.5V for my motor? I assume not. I only have one motor which is another reason for the inadequate power. My last option would be to get a more powerful motor, as I would have to remove many things, some that have been permanently fixed.

Could I also use button cell batteries? For either the arduino or L239D? Their current output seems to be too low, so I doubt it. The run time I am looking for isnt long, 10-20 minutes ideal. Would I be able to use a small lipo as external power for the L239D?

Thanks

You lose at least 2 volts and as much as 4 Volts to the motor with the ancient and inefficient L293. Replacing that driver with a modern driver like the ones available from Pololu would be a good upgrade.

The voltage of the batteries is important, but the current capabilities are actually as important if not more so. 9V transistor batteries (small rectangular smoke alarm batteries) have very low current capability.