Originally Posted by Bandicoot

Is this really a problem with modern Li-ion batteries? I've kept some power banks I have fully charged repeatedly, over months, and have not seen any deterioration in functionality. My understanding is that most battery makers now include controls in the battery to prevent harmful levels of charging anyway, so when it says it's 100% charged it's already not really full but at some optimal level determined by the manufacturer, and we don't need to second-guess that.