With the flying season in Canada all but over in most areas, or at least on a much reduced basis, you want to make sure you take proper care of your LIPO (LIthium POlymer) batteries during these long down periods.
Avoid keeping LIPOs at full or low charge levels for extended periods of time as it causes the chemistry to break down faster and thus reduce the lifespan of the battery. Storing your batteries at the proper voltage level is one of the simplest thing you can do to lengthen their life.
Typically it is recommended to store LIPOs at around 3.8V per cell or 40-60% of their capacity. A fully charged cell is 4.2V.
Most chargers have a “Storage Mode” to set the LIPOs to their optimal storage voltage, reducing or increasing the charge as needed to get to this level. The actual storage voltage can vary slightly from brand to brand of chargers but they are typically with the 40-60% capacity range.
Keep your storage charged LIPOs in a cool dry location, ideally away from flammable materials and protected from any potential damage. Around 3-5C is often considered the ideal storage temperature but any cool temperature above freezing is generally fine.
For batteries such as the smart LIPOs in the new Phantom 2 and Vision there is no built in means to set them to storage via the charger. In those instances the simplest means it to fly the packs until they are in the 40-60% range which will be the general voltage for storage.
As always, take care when charging LIPOs, never leave them unattended in case of potential shorts/overcharges that could result in fire.