I've been using 65-75% for storing. Have been told that routinely charging lipo to 100% and then not using it causes damage. I don't think anybody knows the time frame though - leave them a few days, several, a week or two?

When I get finished running, I charge them to 65 - 70% and then recharge before using. I left come stored at 50% for almost 3 months and they all puffed. I don't use 50% any more.