Li-SOCl₂ batteries for asset tracking devices
Sleep current, reporting interval and the peak of a position fix decide the pack; nominal capacity alone does not.
A tracker spends most of its life asleep, then wakes to take a position fix and transmit it. The battery has to carry the standing load between reports and the peak of the fix and the transmission, and it has to do so at whatever temperature the asset sits in — a vehicle roof, a container, a yard in winter.
The reporting interval usually decides service life far more than the cell’s nominal capacity does. Tell us the interval, the working current between reports, the peak current during a fix and during transmission, how long that peak lasts, the cut-off voltage of the radio module and the temperature range the asset sees in service.
What decides the battery
Reporting interval
How often the device wakes, fixes and transmits — usually the dominant term in service life
Working current between reports
Sleep and idle draw, including any watchdog or sensor activity
Peak current
The current during a position fix and during the radio transmission
Pulse duration
How long that peak lasts, for the fix and for the transmission burst
Cut-off voltage
The lowest voltage the radio module tolerates before it resets
Operating temperature
The range seen in transit and on site, including cold-start conditions
Enclosure and mounting
Available space, how the pack is fixed and how it is replaced
Which configuration fits
A tracker with infrequent reports, modest transmissions and a wide voltage window can run from a single ER cell. Where the fix or the transmission pulse pulls the voltage towards the module's cut-off level, an ER + pulse capacitor configuration separates the pulse current from the standing load. Where the required capacity, the voltage or the enclosure rules out a single cell, a series or parallel pack is built to the space available.