Coin-Type Primary Lithium Batteries for Electric Smart Meters

Next-generation electric smart meters, which have been increasingly adopted in recent years, are evolving beyond simple power measurement devices into data platforms that support social infrastructure.  Current smart meters transmit and receive data at 30-minute intervals; however, next-generation models will enable data communication at shorter intervals. This advancement allows measurement data to be acquired and utilized in near real time, and enables the addition of time information (timestamps) to non-fossil energy certificates.

In addition, real-time visibility of electricity consumption at both household and regional levels enables demand response (DR). DR encourages energy savings during shortages and promotes energy use when surplus electricity is available. This plays a crucial role in maximizing the use of renewable energy and is a key enabler for the realization of Virtual Power Plants (VPP).As part of CO₂ reduction initiatives, hourly matching is gaining attention within the SBTi framework, which references the GHG Protocol. Electric smart meters play a critical role in acquiring the time-based demand data required to achieve this.

Electric smart meters are typically powered by the electrical grid during normal operation.　Primary batteries are used as a backup power source to support functions such as the Last Gasp, which immediately sends notification of power outages. and to retain data in memory during ongoing processing within the meter.　For communication-driven functions such as Last Gasp and for long-term data backup, cylindrical primary batteries are primarily used.　On the other hand, for low-current backup applications—such as maintaining time data in the internal clock (Real-Time Clock: RTC)—coin-type primary batteries may be used in combination with cylindrical batteries. In emerging markets, where low-cost and simplified smart meter designs are in demand, there are also cases where coin-type primary batteries are used exclusively. The key requirements for coin-type primary batteries used in electric smart meters are as follows:

■ Long-Term Reliability

Electric smart meters generally have a service life of 10 to 15 years. Therefore, batteries must maintain reliable performance over this extended period, particularly for backup operation during power outages.

■ Voltage Stability

A drop in supply voltage may cause interruptions in communication processing or temporary connection failures. To ensure stable system operation, batteries must be capable of providing a stable voltage over a long period of time.

■ Wide Operating Temperature Range

Electric smart meters are often installed outdoors or in harsh environments. Therefore, batteries must be capable of operating reliably over a wide temperature range, from high to low temperatures, and ensure stable performance over long-term use.

Coin-Type Primary Battery Models for Electric Smart Meters

A minimum operating voltage is defined for the Real-Time Clock (RTC) in electric smart meters to function properly. If the voltage falls below this threshold, the RTC may fail to operate correctly, potentially requiring the time data to be reset.　This figure shows the discharge characteristics of the CR2450.At an ambient temperature of 20°C, the battery exhibits a flat voltage curve.

This characteristic enables the CR2450 to provide a stable voltage required for RTC backup over an extended period, thereby contributing to improved reliability of electric smart meters.

Discharge Characteristics of CR2450 (20°C, 6.8 kΩ)

Electric smart meters are expected to operate over a long service life of 10 to 15 years. Therefore, backup batteries for RTC applications must exhibit low self-discharge characteristics. Panasonic’s coin-type primary batteries offer a low self-discharge rate of less than approximately 1% per year at 20°C.This enables long-term stable operation as an RTC backup power source, reducing the need for maintenance over the product lifetime.

Electric smart meters are often installed outdoors, requiring batteries that can operate reliably across a wide temperature range. The CR2450 operates within a temperature range of –30°C to 85°C, ensuring stable performance regardless of installation location or seasonal conditions. In addition, the high-temperature coin-type battery BR2477A supports an even wider operating range of –40°C to 125°C, enabling reliable operation in more demanding environments.

In addition to a wide range of coin-type lithium primary batteries, Panasonic Energy also offers cylindrical lithium primary batteries featuring long life and high reliability for applications requiring higher power, such as Last Gasp communication and data backup.　We provide optimal battery solutions tailored to customer applications and requirements.

Panasonic Energy maintains multiple production sites for battery materials, as well as cell and pack manufacturing.　Through this global network, we deliver products reliably and efficiently over the long term.　With sales bases worldwide, we are also able to provide close, localized support and communication to our customers.

Panasonic Energy’s business encompasses batteries that support everyday convenience and comfort, as well as power solutions for a wide range of social infrastructure and automotive applications, including EV.　We contribute to the realization of a sustainable society where enhanced quality of life and environmental responsibility are in harmony.