London Underground battery-electric locomotive.

UK: The prototype for the refurbishment of 29 battery-electric locomotives used on London Underground engineering trains is now undergoing trials.

The locomotives each have 168 vented lead acid cells to provide power for traction and wagon-mounted equipment when the fourth-rail supply is turned off. Modernisation is being undertaken by LU's TransPlant unit, which decided to retain lead acid cells after rejecting nickel-cadmium due to size and weight considerations, as well as fuel cells because of storage and installation issues.

Exide Technologies was asked to develop a new cell to replace the 1960s design. Manual installation of the old cells used to take eight staff two days to complete and needed two people to work inside the locomotive designed to fit within the small profile of LU's deep-level lines.

The new cells are taller and thinner, and can be installed in banks of 12 using a forklift truck. This takes two staff less than 2½ h, and also reduces the handling risk.

The refurbishment also includes fitting LED lighting and improving cab ergonomics and access.