Power Budget & Battery Life Calculator

Estimate battery life from a device's full duty cycle — wake, sensors, and radio — over NB-IoT/LTE-M, LoRaWAN, or Wi-Fi. Add the same sensors you'd configure in IsurDASH; 4-20mA and Modbus sensors are usually the biggest single draw, since they're powered from the 9-24V VDC rail, not the battery directly.

Example values

Radio timing (wake/prep/TX duration and current) is calibrated against real measurements for NB-IoT, LoRaWAN, and Wi-Fi. Sensor-specific defaults and battery usable-capacity derating are still engineering estimates — adjust them under each widget's "Advanced" section as real measurements (Power Profiler Kit, datasheets) become available.

Not infallible

Even with all these parameters, this is still a model, not a guarantee — real deployments see extra variability the calculator doesn't account for:

Temperature. Cold weather reduces usable battery capacity and raises internal resistance — it worsens the passivation effect on Li-SOCl2 cells in particular.
Battery state of health. Capacity fades with cycle count and calendar age (self-discharge tends to increase too), so a battery near end-of-life will underperform this estimate.
Coverage / signal strength. Poor NB-IoT/LTE-M or LoRaWAN coverage means more retries, longer connection times, and sometimes higher transmit power than the modeled defaults.
Unscheduled transmissions. Events like a vandalism/accelerometer alarm trigger extra wake-and-send cycles outside the regular schedule, which aren't part of this periodic model.
Manufacturing and component tolerances. Real current draw varies chip to chip and unit to unit from datasheet nominal values.

Treat the result as a planning estimate, not a warranty figure.

Configuration

Connectivity

NB-IoT / LTE-M

LoRaWAN

Wi-Fi

Schedule

Latency time 10 min

Record accumulator 6 reads/tx

Advanced

Sleep current 80 µA

Boost converter efficiency 85 %

ESP32 wake overhead (per cycle, before sensor reads)

Wake current 44 mA

Wake duration 5000 ms

Sensor ADC/register read time (after pre-acquisition) 50 ms

Radio — modem prep (ESP32 + modem awake, AT handshake, MQTT/signal check — before the actual burst)

Prep current 35 mA

Prep time 8 s

Modem AT retry penalty (firmware < v2.0.0), at prep current 3000 ms

Radio — burst transmission (the actual over-the-air send)

TX current 180 mA

TX time 1 s

Radio tail after TX 0 s (RAI on)

Battery

Chemistry

Li-Ion

Li-SOCl2

Number of batteries

Advanced

Self-discharge 1.0 %/month

Cell capacity (per battery, rated)

Li-Ion cell (INR18650) 3400 mAh

Li-SOCl2 cell 19000 mAh

Usable capacity (vs. rated — accounts for cutoff voltage margin and, for Li-SOCl2, passivation under pulsed loads)

Li-Ion usable 85 %

Li-SOCl2 usable 85 %

Sensors

No sensors added yet — add one above. Sensors usually dominate the power budget.

—days

— months · — years

Daily energy breakdown

Sleep Wake Sensors Modem prep TX Tail Self-discharge

Reads / day—

Transmissions / day—

Sleep charge / day—

Wake charge / day—

Sensors charge / day—

Modem prep charge / day—

TX charge / day—

Tail charge / day—

Self-discharge / day—

Charge used / day (sum)—

Avg. current draw—

Energy is computed per power domain: onboard sensors and radio/ESP32 draw is counted directly against the battery pack voltage; 4-20mA and Modbus sensors are powered from the boosted 9-24V VDC rail, so their contribution is converted to battery-equivalent mAh (V×I×t ÷ battery voltage ÷ converter efficiency). Self-discharge is modeled as a constant daily drain proportional to total capacity.