2. 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.