I'm a new owner.  I've ridden a few times and barely touched the battery usage. I've recharged per instructions. Now, due to cold weather, I need to set the bikes aside for a few months.  How do I store the batteries that are currently on full charge?  I couldn't ride enough to get the power down by much - it's cold outside.  Is it critical that I take 25% off the charge or just store as is?  Do I put the bike up on blocks and try to run down the power or is there another method or is not that critical.