Zigbee Battery Life Calculator | Current Based Formula

One of Zigbee’s strongest advantages is its ability to operate for years on small batteries. Accurately estimating battery life based on current consumption is critical during product design. The Zigbee Battery Life Calculator (Current Based) provides a quick way to estimate operational lifetime using current draw values. The formula calculates battery life based on how long a device can operate based on sleep, transmit and receive currents

Understanding Current Based Battery Life

Battery life depends on following parameters.

• Active current consumption
• Sleep current consumption
• Duty cycle
• Battery capacity

Even small increases in average current can significantly reduce device lifetime.

Typical use cases include zigbee end devices, Battery powered sensors, Smart switches and remotes and wearable or portable IoT devices.

Zigbee Battery Life Calculator

INPUTS:

Radio and MCU current consumption :

• During Tx (Itx) = 35 mA
• During Rx (Irx) = 25 mA
• Sleep (Isleep) = 3 μA

Timing per cycle :

• Tx mode (Ttx) = 4 ms

• Rx mode (Trx) = 6 ms

• Sleep (Tsleep) = 4.99 seconds

• Total Cycle Period (T) = 5 seconds

• Battery Capacity (C) = 240 mAh

OUTPUT:

• Battery Life = 3934 Hours
• Battery Life (Years) = 0.449 Years

Zigbee Battery Lifetime formula

Following equations are used for zigbee battery life calculations as per current consumption during transmit, receive and sleep intervals.

Summary: Current based battery life estimation provides valuable insight into real world Zigbee device performance. By using accurate current values, engineers can design Zigbee devices that meet long term reliability goals while minimizing maintenance and battery replacement costs.

References

• Texas Instruments, Zigbee Power Consumption and Battery Life Calculation, Application Report SWRA478, 2018.
• Silicon Labs, Energy Optimization Techniques for Zigbee End Devices, Application Note AN1017, 2019.