The discharge pattern of a downhole battery depends on the specific type of battery chemistry and its design. Generally, downhole batteries are designed to provide a relatively constant voltage output throughout their operating life until they reach their end of life.
The mode of discharge chosen will have a significant impact on the life of the battery in a given application.
There are three typical modes of battery discharge.
Constant Resistance (“R”): In this mode, the resistance of the device load remains constant throughout the discharge process.
Constant Current (“C”): In this mode, the current consumed by the device remains constant during discharge.
Constant Power (“P”): In this mode, the current during discharge increases as the battery voltage decreases, thus discharging the battery at a constant power level.