Battery80

To keep your gadgets humming for many years to come, stop charging them from zero to 100 percent, says Cadex Electronics, which designs power-monitoring systems. Instead, keep the battery meter between 40 percent and 80 percent.
Research shows that living to the extremes can wear out lithium batteries. Each time you plug in a gadget, it holds onto a little less energy than it did the time before. That's why laptops that once lasted for hours on a single charge eventually demand regular refills. After a certain number of recharge "cycles," the battery becomes weaker and weaker.

The average lithium battery can go from empty to a full charge between 300 and 500 times before it expires, according to Battery University, an online clearinghouse for battery research. But using the full spectrum of a lithium battery actually causes stress, reducing its longevity. That same battery could have lasted through 1,200 to 1,500 fill-ups if it went from zero to a 50 percent charge. By filling it up only halfway, you triple or quadruple the number of recharges.