I was now about to power a microcontroller (3.3V) and a servo (HS-755 HB) externally via batteries. The target is to have the max. life time.
The servo will work with 4.8V or 6v as the max. Torque changes respectively.
After researching about batteries I have identified two feasible options (considering price, mobility and space) disregarding the mAh value of the batteries.
Option 1: 4x 1.2V AA Nimh batteries –> 4.8 V
Option 2: 4 x 1.5V AA Alcaline batteries –> 6V
Currently the advantage I see at the Nimh batteries is that they supply an average 1.2V throughout most of their discharging life time whilst the voltage of alacaline batteries drops quickly.
As I have followed this discussion (see link below) it is said that the Nimh batteries will go below 1.1V after 70% usage whilst the alcaline will go below 1.2V even after 50%. I guess my servo will not work if the Voltage drops <4.8V.
Is my choice of Nimh batteries the most beneficial one considering maximum time of usage for me as long as the torque provided with 4.8V is sufficient? Is there any mistake in my assumption?
Replacing 6 series AA alkaline batteries with NiMH batteries – how do I compare possible arrangements to optimise usable capacity?
dathasheet of the servo: http://cdn.sparkfun.com/datasheets/Robotics/33755.pdf