Attended a really informative clinic on battery power by Duncan McCree of Tam Valley. Among other things, he brought forth the need for battery locos to have an on/off switch. It may seem obvious, but the point had previously escaped me. Without it the loco. batteries would go dead after about 24 hours.
Portions of his handout can be found here: http://www.tamvalleydepot.com/deadrailsystem.html