Let's go from this... this! 
And actually, these pictures are waaaaay out of date. Sophie is
now  outfitted with hi-tech Lithium Iron-Phosphate batteries that
are computer controlled and mounted entirely inside the
locomotive. The tender that used to carry all that messy bulk you
see in the pictures above is now EMPTY (except for the driver
and the 12V system battery). Sophie can now pull trains for up to
4 days on a single charge!

This battery-electric direct-axle drive served as the prototype for
development of ground-breaking drive systems for new 24-inch
gauge park and zoo locomotives now being built by Texas Bells
and Whistles. Keep your eyes open for many of our new electric
locomotives pulling trains across the country soon!