Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Altoona Works BP4 is a 1,350 hp B-B battery-electric locomotive rebuilt by the Altoona Works of the Norfolk Southern railroad. It is the result of a conversion of an existing EMD GP38-type locomotive. This involves replacing the existing prime mover with a set of 1080 12-volt lead-acid batteries, and associated control equipment. Despite appearing somewhat similar to a conventional diesel electric locomotive, the BP4 has no diesel engine, battery charging is provided by pulling in an external power source.