I had the problem with a "replacement" battery on my Nokia 1520 only charging to roughly 81% capacity. It turned out the replacement battery was an after market item and not an OEM. Once the battery was replaced with an OEM (a little more expensive), the phone worked perfectly again. I tried all the obvious troubleshooting tricks and nothing worked except the OEM battery. It was $90 installed at a local computer repair center in Ohio (WGA - they accept repair items by mail http://wgacsc.com/refurbished%20and%20re...). The install took about an hour and hopefully I don't have to buy another expensive phone for a couple years.