There is one major reason why your phone battery keeps prematurely dying, and it’s completely within your control.
Love a bright screen? Unfortunately, that overly bright screen could be to blame for a dwindling battery.
The first step to take is to activate auto-brightness. GO to Settings > General > Accessibility > Display Accommodations and toggle Auto-Brightness to on. “Your phone will then adjust its brightness based on your current lighting situation,” reports PC Mag. “If you have enough light to see, the screen will turn itself down and save battery life.”
There is a manual option for controlling brightness, as well: go to Settings > Display & Brightness and use the slider bar to dim or brighten your screen as you wish.
Wondering how much the brightness setting is costing you in battery power? According to a Lifehacker study: “an iPhone 4 should last about 6.5 hours of continuous use on the lowest brightness setting and about 3.5 hours on the highest brightness setting.” Shaving that much time from your phone usage because of a too-bright screen is significant. Change the brightness setting and extend the time between phone charges.