Lithium Ion has become very popular because of its many performance benefits. One of the key concerns with NiCd / NiMH is their self-discharge characteristic. A full battery, when left in storage, may not retain its charge for very long even if it is not used. This self discharge behavior is aggravated at high temperature storage conditions. Li-Ion provides higher energy in a smaller package, and much better capacity retention in storage than the nickel-based systems. The main drawback of Lithium Ion batteries is that they require precision electronics for monitoring and control, to ensure safe and reliable operation. Despite this drawback, Li-Ion has become the most popular choice for a huge variety of portable electronic devices.