Can I upgrade the battery?
The battery is actually quite large. Our battery pack is 2600mah @ 11.1 nominal volts.
We use three A Grade 18650 cells and that gives you up to 40 hours play time between charges and will also give you plenty of power to charge your phone. Keep in mind that a small phone charger with 5v DC output is called 2600mah, but is often just one 18650 cell and a boost converter.