Saft's specialized MSX nickel-based rail batteries offer Bombardier Transportation space saving and weight reduction benefits

March 23, 2012 // By Paul Buckley
Bombardier Transportation has selected Saft’s new generation MSX high power compact rail batteries to provide safety‐critical onboard backup power for a fleet of 30 dual-system FLEXITY Swift tram‐trains currently under construction for the German city of Karlsruhe.

In addition to offering substantial savings in battery size and weight compared with lead acid batteries, Saft’s advanced nickel-based technology also provides Bombardier Transportation with total confidence that the onboard batteries will deliver the high power performance required by the tram‐train’s electro‐magnetic braking systems, even in the coldest winter conditions.

The city of Karlsruhe was the first in Germany to link its street tramway and the main‐line railway by running urban trams on both networks. This required the creation of dual equipment tram‐trains with the capability to operate from both 750 V DC and 15 kV AC supplies. The 30 new FLEXITY Swift vehicles are being introduced to provide additional passenger capacity, to replace some of the older tram‐train vehicles and to extend the route coverage of the existing network. The new 37 meter long vehicles consist of three modules, with the capacity to carry 244 passengers, and the interior is walkable throughout its entire length.

“High power performance and optimizing the overall size and weight of the roof‐mounted battery package were the critical factors when we specified the onboard batteries for the Karlsruhe tramtrains, and the Saft MSX nickel‐based batteries have proved to be the ideal solution in every respect,” said Uwe Donath, Bombardier Transportation’s project leader for electrical integration. “By switching from lead‐acid batteries we are saving around 30 kg in weight and reducing the size by 25 percent, with complete confidence that the compact Saft batteries will deliver the very high braking loads we require even in winter temperatures that can fall as low as ‐25°C.”

To change the power supply from DC on the tram tracks to the AC used by the main‐line trains (or vice‐versa) the tram‐trains have to pass a cut‐off section of 50 to 250 metres in length where no external power is available. This requires the 24 V (nominal) onboard battery system to support all the vehicle electrical loads for a period