The best use of a battery on a train is a small one to handle junctions. You disconnect from the wire at the end of one set, go through the junction, and then reconnect at the other side. Saves a lot of ugly spaghetti wiring.
You don’t even need that. Every electric train I know of has pickups on each car, and any break in the catenary or third rail is short enough that it can be bridged naturally by two cars, or sometimes even just one, if it has pickups at both ends.
The best use of a battery on a train is a small one to handle junctions. You disconnect from the wire at the end of one set, go through the junction, and then reconnect at the other side. Saves a lot of ugly spaghetti wiring.
Otherwise, no, just use wires.
You don’t even need that. Every electric train I know of has pickups on each car, and any break in the catenary or third rail is short enough that it can be bridged naturally by two cars, or sometimes even just one, if it has pickups at both ends.