Question: How do you calculate the battery life in a battery-powered application?
Answer: The processor is put to sleep and wakes up regularly to perform certain tasks; after it completes the tasks, the processor goes back to sleep. The following parameters are required to calculate the life of the battery in a battery-powered application:
Sleep Current: The current drawn from the battery when the processor is asleep.
Time in Sleep: The time the processor spends in sleep mode in a second.
Active Current: The current drawn from the battery when the processor is awake and is performing the required tasks.
Time in Active Mode: The time the processor spends in active mode in a second.
Capacity of the battery in mA-H: Using the values of Nos. 1, 2, 3, and 4, the average current consumption per second is calculated. Using this average current and the capacity of the battery, the life of the battery is calculated.
You can use the Visual Basic application attached to this article to calculate the battery life. Key in the On Time, Sleep Time, Active Current, Sleep Current and Battery Type or Capacity, click “Calculate,” and the application will calculate the approximate battery life expected.