Every time you go through a charge cycle on your iPhone, you'll permanently lose anywhere from 30 seconds to a minute of battery capacity. Typically, you'll get 250 to 500 charge cycles before a lithium ion battery has outlived its usefulness, Vronko says.

(A charge cycle covers the entire capacity of the battery. For instance, if you drained a third of the battery and recharged it, and then used two-thirds of the battery the next day and recharged it, this would still be considered a single charge cycle.)

Using your iPhone in extreme temperatures--below 40 degrees Fahrenheit or above 95 degrees--will degrade the battery capacity faster, he says. Also, you shouldn't regularly run your iPhone battery completely down before recharging it. Doing these things will shave maybe a minute and half off the total battery capacity per charge cycle, Vronko says.

However, it's a good practice to run the battery dead before fully recharging it once a month to keep the chip on the battery and the chip on the device that measure the current flowing back and forth in sync . This is one of Vronko's .

There are ways to improve battery life of a single charge cycle. Here are :