Been using lipos for a long time. First in R/C cars and now in my drones. I store my batteries in an "after-run" state. I never check the actual voltage. Stored batteries like that for over 3 years with zero issues. If I know I'm not going to run my packs for a month I'll bring them up to 50% and leave them...
I store my "H" batteries at 13.9 to 14.3 volts. I only know that cause thats what the volts read when I land it....