When using it the same way I used to use the s3: The s3 I needed to change the battery by 4:00 PM but with the s5, it lasts at least till 10:00 PM. It also charges much much quicker than the s3. So if you just give the s5 just a little charge in middle of the day, like in the car, then you're good to go till you go to sleep! Also, the s5 has an ultra power savings mode that you can put on if you're running low on battery, which makes the screen black and white, and stops all non necessary applications. Ultra PS mode is supposed to last very very long on sleep. So that's a nice thing to have in case of emergency as well.