For longer dives in cold water I prefer Saft LS14500 lithium batteries for their capacity and runtime. I have seen an 1.5v Energizer Ultimate Lithium die during a dive after starting with a full indicator. With correctly set battery type... The extra juice in saft probably allows you to finish your dive after indicator starts falling.
Shearwater has good articles about battery choice on their website.
Shearwater has good articles about battery choice on their website.