 Following this, a number of battery vehicles were built by converting redundant motor cars, with the batteries placed in the unused passenger compartment.One exception to this was made by the City and South London Railway, who used a trailer car to hold the batteries, and wired them to a separate locomotive.From 1936, battery locomotives were built as new vehicles, although in most cases, some components, particularly the bogies and motors, were refurbished from withdrawn passenger cars.