Happy New Year! Thank you for letting us know the problem via the community and thanks a lot for the reply from @TechnicallyWell.
From what you've described, we assume the battery is abnormal. Could you please email us via support@Anker.com with your order information and problem details? We will arrange our warranty claim for you based on the 18-month warranty policy.
Sorry for any inconvenience caused and thanks for your support.
My best wishes to you in 2018!