gprs
Communications

Overview

With the rapid development of communication technology, IoT equipment has higher and higher power supply requirements, including discharge platforms, energy density, operating temperatures, safety and reliability, and life expectancy. Smart water meters, smart gas meters and GPRS/GSM tracking devices are characterised by a need for remote communication.

This article first appeared in Metering & Smart Energy International issue 2-2018. Read the full digital magazine here or subscribe here to receive a print copy.

Besides high-energy density and the high pulse capability, these applications require a battery system that can withstand extreme conditions (-40 ˚C to +85 ˚C). In these cases, primary lithium batteries are usually one of the best solutions, due to the inherent long lifespan and high energy density of the product. However, due to the increasing complexity of featurerich electronic or electromechanical devices, the performance of the current generation of primary lithium batteries is being challenged and a better power solution is required.

Power solutions in GPRS/GSM modules

One typical example of a ‘high-current pulse application using a GSM/GPRS-GPS system’ is one where the equipment is integrated with an independent power system that requires all the following features:

a) High pulse capability (2A peak current)

b) Long term energy output (1.12 Ah per year)

c) A lifespan of more than 5 years.

Its application mode is as below:

New power solution for high current pulse applications EVE recommends the ER34615 and the SPC1550 hybrid power solution as the required power source. A D-size lithium-thionyl chloride battery (ER34615) can be used to charge an AA-size lithium-ion based battery capacitor (SPC1550) consistently and steadily. This is because the lithium-thionyl chloride battery outputs a stable discharge voltage, high-capacity (nominal capacity of 19 Ah) with low self-discharge rate (<2% at room temperature.

According to the data, at room temperature (RT) the self-discharge of the ER34615 and the SPC1550 hybrid power system is lower than when either is used on its own. The SPC1550 battery capacitor drains the ER34615 battery continuously which can prevent the voltage delay caused by the passivation film of the lithium-thionyl chloride battery. As a result, the ER34615 and the SPC1550 hybrid power system can satisfy the requirements of continuous high power (1~2 A) drain and long operating life, coupled with safety and reliability.

Reliability under harsh environments

The ER and SPC hybrid power supply has the advantages of both ER battery and SPC, i.e., high energy density, lower selfdischarge rate, high power output and wide temperature range.

Further tests were done which examined the impact of voltage changes on the ER34615 and the SPC1550 combination stored at 70ºC for 90 days. The open-circuit voltage and the load voltage with 2A/100ms pulse are very stable, which also shows that the hybrid power system has the advantages of zero passivation, no substantial increase of internal resistance, low self-discharge rate and no voltage loss.

Pulse train of 2A/100ms pulse after 100mA/5s pulses every three minutes, delivered by the hybrid power solution.

Pulse train of 2A/100ms pulse after 100mA/5s pulses every three minutes, delivered by the hybrid power system.

R34615 and the SPC1550 hybrid power system, pulses2A/100ms.

Conclusion

The power supply solution has the features of a wide operational temperature range, low self-discharge rate, long operating lifetime and high safety and reliability that can be used as a main or backup power source for IoT devices.

After 8 year’s in the field, the application has saved tens of millions in costs for customers, who have also widely endorsed the quality of the products. MI

About the author

Janis Wu is responsible for developing relevant hybrid battery technologies; for customer technical issues in the Application Engineering Team; and battery evaluation in the Reliability Test Center.

About the company

EVE has owned the core business including lithium primary battery, lithium-ion battery, power system, and others. Its products cover smart grid, intelligent transportation, smart security, energy storage, new energy vehicles, special industry and a series of industries.