Long-Life IoT Logger with LTE-M and 4–20 mA Inputs

How the NORVI EC-M12-BC-C6-C-A delivers multi-year, maintenance-free remote monitoring for industrial and environmental applications

Deploying a reliable IoT data logger in a remote field location sounds straightforward – until you factor in power constraints, unpredictable weather, and the cost of maintenance visits. For engineers working on industrial remote monitoring, water utilities, environmental sensing, or agricultural automation, battery life and rugged connectivity are the two factors that make or break a deployment. The NORVI EC-M12-BC-C6-C-A is purpose-built to solve exactly these problems. Equipped with a 38,000 mAh lithium battery, an IP67-rated enclosure, and LTE-M / NB-IoT cellular connectivity, it runs for years without maintenance while reliably reading your industrial 4–20 mA sensors the entire time.

Why Long Battery Life Is the #1 Challenge in Remote IoT Deployments

Most IoT sensors consume very little power during operation. The real power draw comes from cellular transmission – and this is where many logger designs fail in the field. Older 2G/3G modems draw hundreds of milliamps during data bursts, quickly draining standard battery packs. That is why modern low-power IoT standards like LTE-M (Cat-M1) and NB-IoT were developed: they deliver cellular-grade reliability at a fraction of the power cost.

The EC-M12-BC-C6-C-A tackles this at every level – from the choice of MCU right through to the cellular modem. Furthermore, the device pairs this power efficiency with two non-rechargeable ER34615H lithium thionyl chloride (LiSOCl₂) batteries – each rated at 19,000 mAh – giving a combined capacity of 38,000 mAh. Therefore, designers choose this chemistry specifically for long-life applications because it has extremely low self-discharge, making it ideal for devices that may sit in the field for 5 to 10 years.

4–20 mA Inputs: The Industrial Standard, Done Properly

The 4–20 mA current loop forms the backbone of industrial instrumentation. Engineers use it in pressure transmitters, flow meters, level sensors, temperature probes, and hundreds of other field devices. Its strong noise immunity over long cable runs makes it ideal for outdoor deployments were maintaining signal integrity matters.

The EC-M12-BC-C6-C-A provides two 4–20 mA analog inputs with a 0–20 mA range and a maximum input voltage of 26V DC. The ADS1115 16-bit ADC performs analog-to-digital conversion, communicates over I2C, and delivers high-resolution measurements from connected sensors. Importantly, the device also supplies a configurable sensor excitation output with 12V, 5V, or 3.3V options, allowing you to power sensors directly from the logger without a separate field power source. This design simplifies wiring and reduces the bill of materials for any deployment.

Analog Input Specifications

LTE-M and NB-IoT Connectivity: Multi-Network, Wide Coverage

The cellular modem at the heart of this logger is the SIMCOM A7672, which supports LTE Cat-M1, NB-IoT (NB1 and NB2), and GSM/GPRS fallback. This multi-mode approach is important for field deployments where network availability can vary by region or operator. The device supports a broad set of LTE bands B1/B2/B3/B4/B5/B8/B12/B13/B18/B19/B20/B26/B28/B39), plus quad-band GSM coverage, ensuring global deployment flexibility.

Data rates are well-matched to the low-bandwidth telemetry use case: LTE Cat-M1 delivers up to 588 kbps downlink and 1,119 kbps uplink, while NB-IoT provides up to 26 kbps downlink and 62.5 kbps uplink. For a logger sending periodic sensor readings, even NB-IoT bandwidth is more than sufficient – and NB-IoT’s deep penetration characteristics make it valuable in basement or underground installations.

Built for the Field: IP67 Enclosure and Industrial Certifications

The EC-M12-BC-C6-C-A is housed in an ABS + Polycarbonate IP67-rated enclosure – meaning it is fully protected against dust ingress and can withstand temporary immersion in water to 1 meter depth. For outdoor monitoring applications, this is the minimum standard you should specify.

Wall and pole mounting options are supported out of the box, and industrial-grade M8 12-pin connectors with cable gland ensure a sealed, professional field installation. The operating temperature range extends from –40°C to +85°C, covering arctic winters through to desert summers. The device carries CE marking under EN 61131-2:2007 and EN 61010-1:2010, providing EMC and safety compliance for industrial environments.

Environmental & Mechanical Specifications

Processing, Storage, and Local Data Logging

Under the hood, the EC-M12-BC-C6-C-A runs on the STM32L072CZT6TR – a member of STMicroelectronics’ ultra-low-power L0 family. This MCU is specifically engineered for battery-powered IoT applications, with multiple low-power modes that dramatically reduce current draw between measurement and transmission cycles

The device includes a DS3231 real-time clock (RTC), ensuring accurate timestamping even through cellular outages or power interruptions. For local data storage – essential when connectivity is lost – a microSD card slot is provided via SPI interface. This means the logger can buffer readings locally and upload them when connectivity is restored, preventing data gaps in your time series.

RS-485 half-duplex communication is also available opening up integration with Modbus RTU sensors and other RS-485 devices for expanded monitoring capability beyond the two analog inputs.

Ideal Use Cases for the EC-M12-BC-C6-C-A

This logger is well-suited for any application where you need reliable sensor data from a location with no mains power and intermittent or limited maintenance access. Common deployments include:

• Water utilities – pressure and flow monitoring across distribution networks
• Environmental monitoring – river level, soil moisture, air quality
• Agriculture – irrigation pump monitoring, tank level sensing
• Oil & gas – remote well-head pressure and temperature logging
• Smart cities – utility metering and infrastructure health monitoring
• Industrial assets – vibration, temperature, or pressure on remote plant

How It Compares: What to Look for in a Long-Life IoT Logger

When evaluating any long-life IoT data logger for a 4–20 mA application, there are five specification areas that determine real-world performance:

• Battery chemistry and total capacity – LiSOCl₂ cells outperform alkaline and lithium-ion in cold conditions and low self-discharge
• MCU power modes – the idle current draw of the processor matters far more than peak clock speed for longevity
• Modem technology – LTE-M and NB-IoT consume dramatically less power overall than GPRS or older 2G/3G
• Local storage – a microSD slot protects against data loss during network outages
• IP rating – IP67 is the minimum for any outdoor, exposed installation

The EC-M12-BC-C6-C-A ticks all five boxes, combining them in a compact, certified package that is ready to deploy in demanding environments.

Conclusion

Achieving genuine multi-year battery life in a cellular IoT logger requires the right combination of hardware choices – and the NORVI EC-M12-BC-C6-C-A demonstrates what that looks like in practice. With 38,000 mAh of LiSOCl₂ capacity, an ultra-low-power STM32L072 processor, LTE-M/NB-IoT connectivity via the SIMCOM A7672 modem, two industrial 4–20 mA analog inputs, and an IP67-rated enclosure certified for industrial use, it delivers a complete, field-ready platform for remote monitoring applications that demand reliability above all else.

Whether you are building out a water utility monitoring network, an environmental sensing grid, or an industrial asset management system, this logger provides the connectivity, longevity, and ruggedness to make your deployment a long-term success. To learn more about the EC-M12-BC-C6-C-A or to request a datasheet, visit norvi.io.