HP 40gs Power Plant

The HP 40gs is powered by 4 x AAA batteries and 1 x CR2032 as a data backup when the main batteries is low or in the pit-stop between batteries change.  With 4 AAA batteries, it should give you a longer time running time between pit-stops.  Besides, the older design with 3 x AAA batteries, I always ended up not knowing what to do with the extra battery that comes in the 4-packs.