Most Lipo battery chargers have a Storage mode. If you dont plan on using them in the next few days it is always best to bring your batteries down or up to storage voltage (approx 3.8v per cell). Common Sense RC Magnum Lipo Charging Bag CSRCLS MAGNUM [Cars & Trucks] Larry's Performance RC Online lprcs Tenergy 2 pk, Fire Retardant Lipo Battery Bag for Charging and Storage, 7x9inches each HRC9721L LiPo Storage Box FIRE CASE L 350x250x210mm Lipo C Storage: Does It Really Need Refrigeration? Our Team Weighs In LiPo Safe Charging & Storage Bag for up to 8S Batt