Battery life of the iPhone while using Wahoo Fitness products varies depending on what App you use, what features you have turned on, and what generation iPhone you have. The biggest battery drains are the iPhone screen and the GPS feature. If you find your battery is dying quickly, try turning down the brightness of your screen in your settings and/or turn off your GPS. You also might be interested in our Wahoo Extended Battery which adds 1.5x the life of your iPhone to any Wahoo bike case.