I Use lipo's in my RC equipment , I can tell you they should only be stored at "storage charge" approx 40% percent charge , avoid high heat , & overcharging ,....& batteries with more than one cell ,should be equipped with a balance lead , & charged with a smart charger that uses that lead to make sure the cells are equalized ,.if they are not you may have one cell that is higher & one that is lower , causing a "dumb" charger" to continue to overcharge ,instead of equalizing the cells , causing problems , & never leave them anywhere hot,. like the dash of your car , I would have thought if the sds uses a multi cell lipo , there would be some sort of equalize cell logic & protection in the charge routine