isacbx wrote:
My battery usually lasts 1h-2h. But yesterday it went from 100% to 20% in 28 minutes of usage..... I'm on iOS 9.2.1. I don't know what to do. And my battery was that bad before I updated my phone to iOS 9. There was a day some years ago that I was charging it so I could go out. When it reached 80% I disconnected it and then it turned off, saying that I had no battery.... Is there a problem with my battery? Do I need to change it? I know there's a iPhone 5 Replacement Program but I typed my serial number and it isn't "eligible for this program". Help me!!!
http://www.apple.com/batteries/service-and-recycling/
All rechargeable batteries have a limited lifespan and may eventually need to be serviced or recycled. Your own battery’s lifespan will vary depending on how you use your device as well as the settings you choose for it.
Your battery is designed to retain up to 80% of its original capacity at 500 complete charge cycles. The one-year warranty includes service coverage for a defective battery. If it is out of warranty, Apple offers a battery service for $79, plus $6.95 shipping, subject to local tax.
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You can download an app called Battery Life through the App Store on your iPhone to see the current state of your battery. Likely, based on your explanation, it has deteriorated and is now in need of being replaced.