20 - 30 minutos
After 2 1/2 years my battery failed to hold a charge and would die after 30 minutes of use regardless of battery status.
Set up the battery replacement guide on my iPad and just followed step by step took about half hour. Went to use the phone and earpiece wouldn't work. Apparently forgot to connect the #3 cable correctly. Now the phone stays charged all day and earpiece works.
Take your time and follow the guide. Be careful!!!