Lithium ion battery life is adversely affected by temperature extremes. High temperatures cause irreversible damage to lithium ion batteries; this damage can be caused during charging or by high outside temperatures. A fully charged battery stored at 40 C (104 F) for a year will have lost 35% of its original storage capacity. The same battery stored at 0 C (32 F) loses only 6% of its capacity. The takeaway message here is that you should store your electric bicycle in as cool conditions as possible. This may mean taking your bicycle indoors in the summer (always a good idea with expensive bikes, anyway), or storing it in a cooler area. Another source of damage is heat from charging, which is most serious in batteries containing carbon anodes. Be careful not to overcharge batteries (such as by leaving them to charge overnight), as the resulting combination of high temperature and charge is very damaging.