Luke didn't know how to utilize the battery, he would have used it for the teleportation device, but it's a bit bigger than the watch.
He didn't want Zoey to hear his thoughts, he knew of her plan of leaving when she got the chance to report to David. 'I don't care what you are planning, you can leave nobody is holding you back,' he thought knowing she would hear them. But he had to find a way to think without Zoey knowing what he was thinking.
He smiled to himself knowing what to do and began thinking the same way he writes his equations so no one would understand him.
He wondered how he would harness his power. 'I planned on making a weapon with it, so it shouldn't be so hard,' he thought in a code.