Just ordered a LK-7900 package off of ebay which appears to include the LK-530 and LK-290. I'm confused though... isn't the LK-530 both a battery pack and an auto cut-off? If so, wouldn't the LK-290 (which as I understand it is solely an auto cut-off switch) be unnecessary? I'm new to the Lukas world, and the Lukas website isn't the easiest in the world to understand, so any insight would be appreciated. Thanks!