Avoid having to buy a pricey replacement battery by being mindful about how you charge and store your smartphone. iStockphoto By Miriam Cross, Associate Editor From Kiplinger's Personal Finance, April 2017 Smartphone batteries weren’t meant to last forever. But replacing the battery in many new phones can be costly. Apple, for example, charges $79 if your iPhone isn’t covered under warranty or AppleCare+. By rethinking how you charge and store your device, you can prolong battery life and save money.SEE ALSO: 8 Best Wireless Phone Plans for Every Type of User For starters, extreme temperatures, especially heat, are bad for the battery. (Apple recommends protecting your phone from temperatures higher than 95 degrees.) Especially when your phone is fully charged, the hotter it is, the worse it is for the battery. “Treat it like your pet,” says Anne Co, a chemistry professor at Ohio State University. Don’t leave your phone in your car on hot or cold days, or exposed to the scorching sun at the beach. Keep your eye on the little indicator that shows how much battery capacity is left. Draining the battery to zero stresses it; better to juice up your device before it hits a 30% to 40% charge. BatteryUniversity.com, an educational website, estimates that a battery that runs down completely before recharging will last for 300 to 500 charge cycles, whereas regular half-charges will amp up the battery to 1,200 to 1,500 cycles. Advertisement Leaving your phone plugged in overnight isn’t a huge deal because the charger typically turns off once the battery charges completely. But to squeeze maximum life out of the battery, unplug your phone before it hits 100%. And before turning off your phone for long periods, such as for an overseas trip, run the battery down to a half-charge.