The aim of this page is to provide an overview of portable, non-rechargeable battery-powered IoT Pro devices and the design mechanisms used to support long battery life under different operating conditions.

Battery Pack Construction

IoT Pro devices use a hybrid battery configuration consisting of a primary Li-SOCl₂ battery and a Hybrid Pulse Capacitor (HPC).

Standard Battery: 1 x 8.5Ah Li-SOCl₂ Battery + 1 x Hybrid Pulse Capacitor

Extended Battery: 2 x 8.5Ah Li-SOCl₂ Battery + 1 x Hybrid Pulse Capacitor

Nominal voltage: 3.6V

Primary cell chemistry: Lithium-thionyl chloride (Li-SOCl₂)

Maximum pulse current: 3A for 1s

Operating temperature: −55 °C to +85 °C

This hybrid battery configuration places minimal instantaneous stress on the primary batteries while the HPC provides the high-current pulses required by the device. This helps maintain a more stable supply voltage during high-current events, supporting reliable device operation and extended battery life.

Power Efficiency

The power architecture is optimised to minimise power losses and maximise the effective utilisation of the available battery capacity.

Device Current Profile

Device power consumption depends on the application and communication technology. IoT Pro devices are designed to minimise consumption during periods of inactivity while supporting the higher current demands associated with sensing and wireless communication. The diagram below gives an indication of the main components for current draw.

• Idle current: Typically ~30µA but depends on the application (includes periodic Bluetooth advertising)

• Periodic Bluetooth Advertisement: Advertising Interval: 2s, Advertising Current: 2mA (5mA peak), Advertising Duration: ~5ms

• Sensor Data Acquisition: Consumption varies depending on the application. Sensors and their entire sensing mechanism can be powered off when not required to minimise consumption.

• Network Registration:

  • Cellular (NB-IoT/LTE): ~1 C; duration is network dependent, typically 30–60 s under good network conditions

• Message Transmission:

  • Sigfox: Payload size dependent

  • LoRa: Data-rate dependent

  • NB-IoT: Network dependent:

    • 3–4s until deep sleep: ~70mC

    • 8s until deep sleep: ~140mC

    • 14s until deep sleep: ~240mC

  • LTE: Typically near instant under good network conditions

Key Power-Saving and Reliability Features

• Configurable Communication Management: Network registration and message transmission attempts use configurable timeouts and retry mechanisms, allowing communication behaviour to be optimised for the application and limiting excessive power consumption during poor network conditions.

• Continuous Battery Health Monitoring: The device periodically measures and reports its idle current (daily by default, configurable), allowing abnormal power consumption to be detected and monitored remotely.

• NB-IoT Power Saving Mode (PSM): T3324/T3412 timers are configurable to minimise power consumption between transmissions while allowing the device to remain registered with the network.

• NB-IoT Transceiver Monitoring: An internal current monitor verifies that the transceiver has entered its expected low-power state after communication. If abnormal consumption is detected, the transceiver can be powered off until the next transmission.

Battery Life Estimate

This section provides example battery life estimates based on typical device operating conditions, including idle consumption, sensor activity, message transmissions, and network registration. Battery life is calculated using 80% of the nominal battery capacity as the effective usable capacity, providing a 20% capacity margin for real-world operating conditions.

Example 1 - Single Channel Pulse (NB-IoT)

• Idle Current: 40µA

• Sensor Data Acquisition: every 15 minutes (pulse counting is event-based; additional consumption is negligible and included within the idle current)

• Message Transmission: every 2 hours

• Network Registration: once per week (assumed average)

Environmental Testing

• Battery performance has been evaluated under low and high temperature conditions to verify reliable operation across the intended environmental range. Testing also included high-current transmission spikes to confirm that battery voltage drop during cellular transmission does not affect device operation, cause resets, or interrupt communication.

• Operation has been verified at supply voltages below the nominal voltage, confirming that the device continues to operate reliably as the battery voltage decreases. The device also monitors and reports the battery voltage, allowing the gradual decline in battery level to be observed and providing an indication of approaching battery depletion.

• Battery performance has additionally been validated through repeated transmission cycles, including deployments where devices transmit as frequently as every 15minutes. This provides practical validation of battery performance under sustained, higher-frequency communication loads.

• Long-term field deployments provide further real-world validation under repeated daily temperature variations and harsh outdoor conditions, with devices operating reliably throughout these environmental cycles.