I have two lithium ion battery packs for my 2019 radrover. The original battery was replaced due to poor range but works for short runs around town. I currently have my replacement battery stored at around 50%. I've decided after much helpful feedback from forum members to go with the 80% charge method. My question is should I be using both batteries to prevent damage or will the new battery that remains unused be ok stored at 30/50% until I need it witch could be several months to years?