This is the Elma System's "Nobi-ta EX," a system for removing sulfation from batteries. It operates using a voltage of 13.5 to 14 volts when the engine is running, and stops when the engine is turned off and the battery voltage drops, so the device will not continue to consume electricity. I've been using it for about six months, and I'm selling it because I've switched from lead-acid to lithium batteries. Thank you for your interest. (Pulse charging device for extending battery life)