There’s a lot of mixed info out there. My greenworks lawnmower battery guideline says:
• If the battery will not be used for 3 months or more, please store the battery in a room temperature environment. Please fully charge before storage.
https://www.greenworkstools.ca/produ...07_English.pdf
Don’t really know what to believe but since these 80V are $150 brand new each I follow their guidance. I’ve killed a Ryobi battery before but I wasn’t sure if it it was because I stored it empty or if it was because I left it in I heated garage all winter.