Increasing Voltage to Adafruit V1 Motor Shield

Hi all, I'm working on a robot that uses a V1 adafruit motor shield as its base. The shield uses 2 L293D dual H bridge drivers to drive the motors, and they are rated to handle currents of 0.6 A continuous. It has an internal mechanism to protect it by shutting down when it overheats. Here is a link to the datasheet. We are using a 7.2 V Nimh battery as a power source.
http://www.ti.com/lit/ds/symlink/l293.pdf

From the datasheet I found that the chip will drop 1.4 to 1.8 V at...

Increasing Voltage to Adafruit V1 Motor Shield