Saft MRX batteries are crucial to the success of Bombardier’s innovative dual-powered locomotives

The ALP-45DP locomotive features Bombardier’s MITRAC dual-power propulsion technology. This technology is particularly suitable for partially electrified tracks, which require high levels of reliability, cost effectiveness, flexibility and respect for the environment. It makes it possible for the commuter trains to operate in both electric mode with power from the catenary line and in diesel mode providing a ‘one seat’ ride that improves passenger comfort and reduces journey times. Thanks to this flexible drive technology these locomotives can be used on the entire networks of the first purchasers, New Jersey Transit (NJT) and Canada’s Agence Métropolitaine de Transport (AMT) in Montreal.

Onboard battery system for electrical supply continuity and diesel engine starting
The dual-powered locomotives require a 72 V onboard battery system capable of meeting four widely varying load profiles. The battery has two primary functions: to ensure the continuity of all vital electronic control circuits and other vehicle loads while traversing neutral sections of the overhead catenary where the AC power supply is interrupted; to provide cranking power to start one of the two 1,567 kW diesel engines. The battery also has to provide backup support for all vehicle control loads in the event of a failure of the battery chargers, as well as support for critical safety loads such as emergency lighting and the train radio system and also for layover periods when the vehicle is stationary with no external supply.

Previous Bombardier locomotives in North America have utilized standard lead acid battery blocks designed for fleet use within NJT, but this was not feasible for the dual-powered locomotive, as Ringo Klein, the System Engineer responsible for Locomotive Auxiliary Power Supplies at Bombardier Transportation’s Locomotive & Equipment Electrical Engineering division explains: ‘All-up weight is a critical factor for the ALP-45DP since it has just four axles and the need to carry both the electrical traction units and diesel engines was taking the design close to the maximum axle limit. The standard lead acid batteries weigh 1,100 kg, while the Saft MRX batteries are only 425 kg but provide equivalent performance. This 60 percent saving has proved vital in helping us bring the total vehicle weight down to our target.

‘A further key advantage of the Saft MRX batteries is their compact design, so the volume claim on the space available in the battery compartment is only around 60 percent of that required by the leadacid batteries.’ Optimized TCO and integrated water filling system In addition to the critical need to save weight, the Saft MRX batteries also provide additional benefits for Bombardier in terms of optimized TCO (total cost of ownership) thanks both to the long service life of at least 15 years in this application, combined with ease of maintenance. In particular, the unique integrated water filling system enables the cells to be topped up in-situ within the battery compartment, minimizing maintenance time and disruption compared to lead acid cell blocks that would need lifting out of the compartment for servicing.

The battery system for the ALP-45DP locomotive comprises a total of 56 Saft MRX cells, with a nominal voltage of 72 V and a capacity of 160 Ah. The first systems have been supplied by Saft in readiness for the dual-powered locomotives to commence track testing in early 2011. Orders for 46 battery systems Over the next two years Saft will supply at total of 46 battery systems to Bombardier. 26 of these will be installed on New Jersey Transit locomotives in the US and 20 on AMT locomotives in Canada.