A tracker that reports beautifully and dies in four months is a failed product. On a low-power wide-area device the radio is the easy part; the design lives in microamps of sleep current, in how seldom the modem wakes, and in a power budget where the datasheet's active figure barely matters.
A cellular asset tracker on LTE-M or NB-IoT has an easy headline job: read a position and send it. The hard job is doing that for years on a single non-rechargeable cell, in a sealed enclosure, across temperature, without a service visit.
The energy is not spent where intuition says. A transmit burst is brief; the device spends almost all its life asleep, and a few microamps of avoidable sleep current — a leaky regulator, a pin left floating, a sensor not fully powered down — will out-consume every transmission over a year.
So the device is engineered as a power budget first: deep-sleep architecture, power-saving-mode and eDRX timing, a location strategy that avoids waking the GNSS when it need not, and firmware that treats every wake as a cost to be justified.
Stated before any of them had an answer.
The device transmits for seconds and sleeps for hours. A few microamps of avoidable quiescent draw outweighs the entire radio energy over the product life.
Active-mode figures are quoted; real battery life is set by leakage, brown-out behaviour and how cleanly peripherals actually power down — none of which the datasheet promises.
A GNSS fix can cost more energy than a day of everything else. When and whether to acquire one is a battery decision, not a feature toggle.
Capacity falls with cold and with pulse load; a cell that lasts in the lab fails in winter if the pulses were not modelled.
The radio spec sells the tracker; the sleep current keeps it alive. Battery life is designed in the microamps between transmissions, not in the link.
The scope of the work, rather than a capability list.
Rarely the subsystem that sounds difficult.
The difference between one year and three is often a single peripheral not fully powered down; finding it needs measurement, not inspection.
Reporting more often or waking faster costs battery; the trade is set with the customer, not assumed.
A cell rated for the average fails under cold pulse load; modelling that honestly is what separates a lab result from a field one.
You cannot run a three-year test; life has to be validated by accelerated measurement and a defensible energy model.
Multi-year life from a single cell, validated by an energy model rather than hoped for.
Quiescent current driven down until sleep, not transmission, is a small fraction of the budget.
A fix strategy that reports usefully without spending the battery on GNSS it did not need.
A power budget the customer can re-use to trade reporting rate against life on the next variant.
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Because a low-power wide-area tracker spends almost all of its life asleep and only seconds transmitting. The link works; what decides whether the product lasts is the current it draws while doing nothing. A few microamps of avoidable sleep current outweighs the entire radio energy over a multi-year life, so the design is a power budget first and a radio design second.
Sleep current and location. Quiescent draw from regulators, sensors and mis-configured pins runs continuously and dominates the total; and a GNSS fix is energy-expensive enough that when and whether to take one is a battery decision. Transmissions, which intuition blames, are usually a minor line in the budget.
By measurement and modelling. The energy of every event — wake, fix, transmit, sleep — is measured in microamp-hours, combined with the duty cycle and a battery model that accounts for temperature and pulse load, to project life. Accelerated testing and the measured sleep current make that projection defensible rather than optimistic.
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