Under very heavy use, the PE may last only 3-4 hours. Under typical use it should last 5-6 hours. If you turn off wifi (and bluetooth) when possible and put it to sleep when not actually using it, you should get 11 hours. The PE's battery life is shorter because the battery is smaller.

Unlike the EE, the PE is not an all-day device and you should have the adapter with you to give it a quick charge in the afternoon. Mine charges in 1-2 hours on the PE adapter, so even a 30 minute charge will give you several more hours.