A battery-powered device can have enough capacity to meet its runtime target and still fail during operation. A common reason is peak current.
A device may consume only 500 mA under normal conditions but suddenly require 3 A when a motor starts, a wireless radio transmits, a camera activates, or a processor enters a high-performance state. If the battery and power path cannot handle this transient load, the system may reset, brown out, lose communication, or shut down unexpectedly.
For this reason, battery selection should not be based on capacity or average current alone. Peak current, voltage sag, internal resistance, power-path resistance, and load duration all need to be considered during the design stage.
Average Current And Peak Current Are Different Design Problems
Average current primarily determines battery capacity and expected runtime. Peak current determines whether the power system can maintain a stable voltage when the load changes suddenly.
