In normal times, we have come to depend on mobile telecom services to work remotely, connect with family and friends, shop, navigate, and more. Voice calls remain important, but data connectivity has become essential, and never more so than during the COVID-19 pandemic, when companies and individuals have become reliant on video conferencing, emails and messaging services to keep work and everyday life going.
The fifth generation of mobile connectivity, 5G, is currently rolling out across the world, adding speed, reliability and bandwidth to our existing communications, and enabling new services. Smart cities, self-driving cars, connected factories, robots and remote medicine will all rely on stable 5G connectivity.
Network failure can be disruptive and costly – according to Gartner, the typical cost of network downtime is $300,000 per hour – so it's vital that cell towers and base transceiver stations (BTS) are protected with back-up batteries. Back-ups for 5G networks have different requirements, but fortunately a new generation of battery technology is emerging to meet those needs.
Cell towers and BTS are often in remote or hard-to-access locations and they are exposed to extremes of weather, from very high and very low temperatures, to rain, snow and storms. Maintenance and repair work, therefore, can be costly and time-consuming and the kinds of batteries the industry relied on for years are not ideal for that situation.
Valve regulated lead-acid (VRLA) batteries, not that different from the battery in a car, were once standard back-up solutions for cell towers. They are large, heavy, and degrade over time because the sulfuric acid solution they use as electrolyte eats away at electrodes. As a result, the battery capacity decreases until the corrosion finally causes the rupture of the internal connection. The battery will then be in open circuit and won’t hold the charge anymore. This is known in the industry as 'sudden death' and requires engineers to install extra batteries to provide redundancy.
These issues mean that VRLA batteries typically have to be maintained and tested every month. Over the past decade, network providers have begun to turn to nickel batteries instead. These have a lifespan of 20 years or more, are maintenance-free because they do not experience electrode corrosion and have therefore a lower total cost of ownership than VRLAs.
Furthermore, they can operate in temperatures between -20 to +50°C (-4 to +122°F), while VRLA batteries typically have a narrower operating range and experience significantly shorter lifespans in high temperatures.
Nickel batteries, such as Saft's Tel.X battery, have been very effective at providing back-up power for the telecom systems used for voice calls with over 100,000 nickel battery strings in service for more than 20 years. In the US, the Federal Communications Commission (FCC) requires mobile providers to guarantee at least eight hours of back-up power, so that customers can call the emergency services in the event of a power outage, particularly one caused by a natural disaster.
As a result, back-up batteries for the telecom network have been optimized to provide relatively small amounts of power for several hours at a stretch. However, data networks have different needs and require a different type of back-up battery.
As data grows in importance, networks are moving away from the large sites that were used to provide coverage in 2G and 3G networks, towards smaller installations and 'micro' cells that provide 4G and 5G data coverage. The trend is for 4G to remain active to support phone calls, while 5G will become the key infrastructure for data transmission, because of its high capacity and low latency. These micro cells are smaller, more numerous and generally closer to the customer than the old installations. That often means less space for batteries, which makes nickel battery solutions a better choice than VRLAs.
If an outage caused a mobile network to lose live transmission of the Super Bowl or the Olympic Games, they would be faced with many angry customers and sponsors... The consequences would be even worse if a self-driving car caused an accident because of a dropped data connection.
It's therefore critical that data networks can rely on their back-up solutions, for anything from 15 minutes to three hours. On the one hand, the battery doesn't need to operate for eight hours, as with telecom systems supporting voice calls. But on the other, it has to provide more power because of the wider range of cutting-edge technology necessary to support high-speed data processing, as well as the powerful radios needed for 5G.
To meet this need, Saft created the Tel.X-Plus nickel battery, optimizing it for these new kinds of network. Like the existing Tel.X battery, it has 99.999 percent reliability and a 20-year lifetime. If Tel.X, with its eight-hour life at relatively low power, is a marathon runner, then the powerful Tel.X-Plus is a world-class sprinter. This new nickel battery is a good example of how Saft is able to take an extremely reliable product and customize it to meet new industry trends, using its know-how and experience in sectors such as rail, aviation or industrial standby.
Data networks are already vital to modern life and will only become more so. They now have the back-up protection they need.