[jamesperrett]

Originally Posted by G6Tanuki

See ftp://ftp.noc.soton.ac.uk/pub/autosu...Comparison.doc

https://www.theregister.co.uk/2009/0...m_beneath_ice/

The first generation of Autosub used ordinary D-cell alkalines in part because they suffered lower loss of usable capacity as the temperature fell.

It is amazing how many old documents people leave lying around

In Autosub's case we would prepare the sub in a warmed container so they would have been at 15-20 degrees when they hit the water and their self heating (due to the few hundred watts taken by the propulsion motor) would keep them at higher than ambient temperatures during a mission. Later versions of the vehicle used Kokam Lithium Polymer cells but these haven't been used under ice (although they have been used in the deep ocean where the temperature is mostly around 2-4 degreesC).