You should only store Lipos at 3.2-3.7 per cell any thing over this will start the chemical reaction in the lipo the same as a full charge ,so any resting the battery is going to have at over store charge will slowly damage the battery
When you buy a new Lipo if you don't charge it, it will be safe in its new state for approximately a year once you start to charge it the chemical make up of the lipo will change ,you can't go back to new state so the only thing you can do from that point on is store charge
Also most get confused with fast charge mode this does not mean the charge rate goes up when charging fast charge will bring the battery up to about 90% so that you can do a quick flight it will not balance the cells as close as the balance charge programme will and the cell balancing happens at 90-100% full charge
When you buy a new Lipo if you don't charge it, it will be safe in its new state for approximately a year once you start to charge it the chemical make up of the lipo will change ,you can't go back to new state so the only thing you can do from that point on is store charge
Also most get confused with fast charge mode this does not mean the charge rate goes up when charging fast charge will bring the battery up to about 90% so that you can do a quick flight it will not balance the cells as close as the balance charge programme will and the cell balancing happens at 90-100% full charge