Abstract: A battery charging assembly for use on a locomotive is described and which includes a diesel engine having a mechanical power output of less than about 50 horsepower; an oil tank coupled in fluid flowing relation relative to the diesel engine and which contains a volume of oil which facilitates the operation of the diesel engine for a time period which is at least equal to a maintenance interval of the locomotive; an alternator coupled to the mechanical output of the diesel engine and which produces an electrical power output to charge a plurality of batteries which are mounted on the locomotive; and an air compressor coupled in fluid flowing relation to the locomotives air system.