The Strava app depends on location services, which require extra battery power beyond what would be used when the phone is in standby mode. However, there are some things to keep in mind that can reduce the battery's discharge rate while running Strava. As a general guideline, we have observed modern phones successfully recording more than 5 hours of activity. However, when using external sensors (see below), we see typical duration closer to about 3 hours.
For specific tips on battery life issues with iOS6, see this article.
Older phones have two factors that contribute to poor battery performance. First, as batteries get repeatedly charged and discharged, their capacity slowly decreases. So a phone that has been recharged a few hundred times will perform worse than when it was new. Second, battery density continues to improve with technology advancement so a modern phone will have better performance potential than an older model.
In general, the idea is to turn off parts of the phone that are not necessary during your ride. By adjusting settings, you can turn off applications and functions so the phone will have more battery power to run Strava for a longer period of time. Don't forget to reset the changes you make to your phone's settings.
Don’t touch that screen
Mobile devices use backlights or LEDs to create the light shown by their displays. These lights use a large amount of energy, so you should minimize or avoid use of the screen while recording a very long activity.
Lock the phone
Turning off the phone's screen is the best way to prolong the duration of battery life.
Turn off unnecessary networking
Here is a list of wireless networking protocols that can be disabled:
Email sync and periodic message retrieval
Recording data from external sensors requires additional power to operate the internal or external radio communications. This applies to both ANT+ and Bluetooth-LE sensors such as heart rate monitors, cycling power meters, and cadence and speed sensors.
Turn off unused wireless protocols
If you are not using ANT+ sensors, do not plug in an ANT+ key or case. If you are not using Bluetooth-LE, you can disable it in the app's settings for Biometric Sensors.