So I tested the Sears DieHard 10/2/50 amp Automatic Battery Charger. The unit MSRPs at $64.99, but way-hey! As of December 23, 2007, it was on sale for a bargain price of only $39.99. ... The Diehard offers spark proof protection in automatic mode, and even includes a Darwin feature for fashion victims who insist on hooking up red to black and.