Lithium-Ion batteries and (air)travel
Lithium-Ion batteries are utilized almost everywhere nowadays. They have a huge capacity but also restrictions. These restrictions are not to be neglected for safety reasons. When they are damaged by any means they become a fire hazard. This is why they are designated with a risc code 9 for spontaneous combustion. For transportation by airtransport they may not contain more than 30% charge (which for this type of battery means empty). Be aware that they have to be inserted in a device when carried in cargohold luggage. If not there is a good chance that security personnel of airport handlers will remove them from your luggage only to find out when you are allready on your destination. Finavia, the handler on all Finnish airports, does this consequently. I lost 3 batteries that way. Luckely I have friends around that airport and one of them secured them for me. When he picked them up they were taken out of a huge pile of confiscated batteries alike. So either put them in a device or in protective casing with isolated terminals in your cabin luggage. To illustrate the danger: burning Li-Ion batteries took down UPS flight 6, a 747-400 freighter on 3 september 2010 near Dubai, destroying the aircraft and killing its pilots.
SO CHECK THESE BATTERIES ON EVERY TIME YOU CAN AND IN BETWEEN ON PHYSICAL DAMAGE!!!
Anyway... Keeping the charge around 40-50% and temperature around 15 degrees celcius when stored for longer periods of time prolongues the lifespan of these batteries hugely.