Are these old battery things safe? I wouldn't be powering, just a base support for the train. Set 7722. : r/lego
Train Battery Box Car with Red Switch and Black Wheels with 'DB 7722' and Weight Table Pattern on Both Sides (Stickers) - Set 7722 (Undetermined Type) : Part x488c02pb01 | BrickLink
LEGO 7722 Steam Cargo Train Set Instructions, Trains
LEGO 7722 Steam Cargo Train, Battery Set Parts Inventory and Instructions - LEGO Reference Guide