Rechargeable lithium batteries are essentially ubiquitous in our daily lives and in virtually every industry from pocket key fobs to billion dollar space programs, in benign as well as extreme environments. Cell production in 2012 was estimated at 4.4 billion cells and expected to double by 2016. However within civil aviation, lithium batteries are still in the early stages of deployment. The general consensus within the industry is that the use of lithium batteries within civil aviation will increase substantially in the coming years. This paper focuses on design considerations with respect to deployment of rechargeable, or secondary, lithium batteries within civil aviation.