I couldn't get ten hours out of it with constant WIFI usage, never. Even with a strong signal. But then I cannot recall an occasion where i've sat down for a ten straight hours surfing the net on this thing and even on a heavy day, I always have 20-30% battery left at night. Battery usage aint really an issue. I've gone a few days without needing a charge when i've had it there to hand to check email, browse the odd site, listen to the odd podcast etc. I doubt you will find another device on the market with battery life asgood as thing right now, and i've looked high and low as it's the most important thing to me when it came to looking for a portable web browser.