Focus LCDs

What does it mean to overdrive the TFT?

That means you are supplying too much current to increase the backlights brightness. Overdriving can shorten the displays half-life and battery life. If you must have sunlight readability, but have limited power supply, then look into a transflective polarizer. Here is a good page with more details on a polarizer film <http://polarizerfilm.com/transflective-polarizer.html>