They're diesel with electric transmission, but not regenerative. Many locomotives have a visible box that contains just arrays of resistors used to burn off cu

They're diesel with electric transmission, but not regenerative. Many locomotives have a visible box that contains just arrays of resistors used to burn off current generated during braking. I always wondered if it would make sense to have a battery "tender" that could accept this current from a relatively stock diesel engine... so you replace, say, four straight diesels with three and one battery tender.