Apple says only that a limited number of customers are affected with the battery draining issue, and declines to give a precise number. However, the quantity of iPhones with battery problems must be relatively small because Apple is contacting their owners individually, by phone. Apple will offer each of these owners a replacement iPhone 5s. A user cannot replace an iPhone battery—it must be replaced an authorized Apple technician.
Over the launch weekend last month Apple sold nine million iPhone 5s, iPhone 5c and iPhone 4s models.
Apple iPhones have a reputation for long battery life and Apple certainty wouldn't want a battery drain issue to tarnish that reputation. That's why Apple is moving quickly to resolve this limited battery life problem and offer replacement iPhones.
Apple has traced the cause of iPhone 5s the battery drain issue to a manufacturing defect that is either making it difficult for the battery to fully charge or limiting its battery life. This defect in no way affects the safety of the iPhone 5s battery.
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