Thanks for posting your concern here. This is AnkerDirect customer service. @nigelhealy, thanks for your professional reply.
Please kindly be noted that the PowerCore 20100mAh battery is a li-ion battery. It's better to store the battery with 2-4 LEDs on.
FYI, there are other details we need to mention for storing the battery well:
- Please store the battery within the temperature range: 20°C-80°C;
- Please use the battery at least once per 3-4 months to ensure its normal lifespan.
Should there be other concerns or questions, please contact us via "firstname.lastname@example.org" for more information.
Have a great day!