Batteries beat the million-mile mark

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Saft Matrics MRX nickel-cadmium (Ni-Cd) rail batteries have just beaten the million-mile mark on the GNER Mallard trains operating a high-speed intercity service for over 17 million passengers a year along Britain’s East Coast main line.

The batteries were first installed on the Mallard trains four years ago and, in contrast to lead-acid batteries that would now have to be replaced, they are expected to continue in service for at least 11 more years.

In early 2003 GNER began a project to totally rebuild, upgrade and refit its entire electric 225 fleet to transform them into the new-look Mallard trains. As part of this process, the existing on-board lead-acid batteries were replaced with Saft Matrics MRX batteries. This decision was based on a TCO (total cost of ownership) analysis that showed Ni-Cd batteries to be the most cost-effective option over the whole life of the train due to their reliability, long service life and extended maintenance intervals.

Nine batteries, each comprising 76 Saft Matrics MRX cells, are fitted to each Mallard train set, while a single battery is also fitted to each DVT (driving van trailer). The main role of the batteries is to provide support for the train electrical systems through neutral sections of track, where there are momentary interruptions to the main power supply. Furthermore, in event of a power failure, the batteries will provide up to 90 minutes of back-up power for vital safety and control circuits such as lighting, door operation and passenger communications.

Mallard trains travel around 270,000 miles a year. So after four years of service it is estimated that the batteries have already given well over a million miles of operation. The Ni-Cd batteries need is a five-year service, including a reconditioning charge, but are expected to keep going for 15 years or more.

The extended service intervals offered by the batteries are also a vital factor for GNER. Previously, the lead-acid batteries would need to be topped up with water every month, the Saft batteries have enabled this interval to be increased to every nine months, while the integrated filling system enables all the cells to be filled from one central point, a simple operation that takes just 10 minutes.