Decades of Saft battery reliability for Beijing subway
With more than 10 million passengers travelling on its network daily, Beijing Subway needs its metro trains to operate reliably and efficiently. That’s why it has been using Saft nickel batteries for onboard backup power since 2006. After many years, these batteries are performing well despite millions of kilometers in operation.
As the world’s most populous capital city, Beijing relies on its metro to underpin economic and population growth. Beijing Subway opened in 1971 and has grown to become one of the world’s busiest metro systems, with accelerated expansion over the last 20 years.
China’s leading train manufacturer, CRRC Changchun Railway Vehicles Company, built the metro trains for lines 2, 6 and 15. Together, these strategic lines carry more than two million passengers every day. Line 2 connects stations in an inner loop following the Ming-era city walls, Line 6 supports important business and residential districts, and Line 15 connects the Olympic Stadium and suburbs in the north of the city.
It’s essential that in the event of a power outage, backup batteries are ready to deliver uninterrupted power for critical safety and comfort systems. These include lighting, ventilation, signaling and data communication, electromagnetic braking, and door control systems to ensure protection of passengers and staff.
Long-term partnership for Beijing subway between Saft and Changchun Railway Vehicles Company
When selecting battery systems for Line 2 in 2006, CRRC wanted predictable performance and low maintenance requirements. It also wanted nickel batteries that would provide a long service life of up to 20 years as well as withstanding the elevated temperatures of Beijing’s summer months. Nickel batteries also eliminate the risk of “sudden death” that can lead to the sudden and irreversible failure of lead-acid batteries.
These factors ensure a low Total Cost of Ownership (TCO) for Beijing Subway. This is total cost of purchase, plus inspection, testing, maintaining, operating and replacement of an asset across every step of its life cycle.
Small battery size and light weight are additional benefits that reduce the TCO for metro trains. A compact battery will free up space for passengers or other systems, whereas low weight will reduce the overall weight of the rolling stock so that less energy is needed for traction. This cuts energy bills and reduces CO2 emissions for every kilometer the train travels over its typical 40-year life.
At Saft, we were able to demonstrate the TCO advantage and track record of our batteries in 2006. As a result, CRRC ordered a total of 96 battery systems for Line 2 trains.
After winning the contract to build Line 15 trains, CRRC turned to us again for 60 battery systems in 2010. It then ordered a further 166 battery systems for Line 6 trains between 2012 and 2014.
Overall maintenance services with Saft battery expertise
Our support for Beijing Subway extends beyond supplying battery systems. Local battery experts provide after-sales services to ensure long life and reliable operation. This technical support helps Beijing Subway’s own technicians deliver effective maintenance, such as topping up batteries with water to maintain the electrolyte level.
We visit Beijing several times a year to carry out inspection, assess battery life, and condition and conduct deep discharge testing to evaluate battery health. We also identify potential issues and propose suggested updates to Beijing Subway’s maintenance procedures. For example, we’ve helped to provide access to the correct maintenance procedures and recommend adjustments to match operational patterns.
Batteries performing well after more than a decade of service
A recent visit in 2020 found the batteries performing well on all three lines after 7, 10, and 14 years and millions of kilometers in operation. The batteries were found to be in good condition, few malfunctions, or other issues. In addition, Beijing Subway’s technicians reported almost no need for corrective maintenance over the years and had used very few of the original spare batteries.
After more than a decade in use, the condition of the batteries demonstrates how CRRC’s focus on TCO has helped Beijing Subway achieve a cost-effective and intelligent long-term backup solution.