Batteries to provide backup on driverless metro

Saft has concluded a framework agreement with Siemens to supply "plug and play" onboard battery systems for all future VAL 208 driverless, fully automated, rubber-tyred light metro projects.

Saft has concluded a framework agreement with Siemens to supply "plug and play" onboard battery systems based on its Matrics MRX cells for all future VAL 208 driverless, fully automated, rubber-tyred light metro projects, starting with 46 four-car trains for Turin, Italy.

An onboard battery, nominal voltage 64.8V, is installed below the floor of every VAL driving unit to provide backup power for safety and auxiliary circuits.

As part of its drive to save space and weight and increase manufacturing efficiency on the new VAL 208, Siemens asked Saft to develop a new, fully integrated on board battery system to replace the existing battery, in which loose cells were assembled into a battery box.

Saft designed a new battery system, comprising 54 Matrics MRX cells in a customised stainless steel box complete with switches, fuses, thermal sensors, connectors and a centralised water filling system.

This not only offers major savings in space and weight, it also significantly reduces manufacturing time and costs for Siemens by offering a more efficient approach as the battery is supplied ready to "plug and play".

A further advantage is that the Saft design offers additional flexibility so that a choice of 90, 100 or 115Ah MRX cells can be specified to enable the battery capacity to vary to meet local project needs, such as a larger capacity for lower temperatures.

Saft developed the Matrics MRX battery in response to customers such as Siemens who were seeking even smaller, lighter batteries optimised for maximum performance, reduced maintenance and low life cycle cost.

It provides the low maintenance and long service life benefits of sintered/pbe technology within a slim, lightweight block battery package, housed in a flame retardant polypropylene case.

The Matrics MRX design is also extremely reliable and does not suffer from the "sudden death" which can affect some batteries, even in extreme temperatures ranging from -30 to +70C.

A further advantage of the Matrics MRX is the centralised water filling system.

This simple to use feature fills all the cells in sequence from one central point - without any moving parts - and substantially reduces the battery maintenance requirements by enabling cells to be topped-up quickly, safely and accurately, maximising the battery's useful life.

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