Traditional automotive lead-acid batteries are housed in the engine bay, whereas the new low-voltage lithium packs are installed under the rear seats or trunk floor. Because the lithium battery 's negative terminal is hidden and out of reach, it cannot be disconnected manually like its lead-acid counterpart. To solve this problem, the paper presents a diagnostic-software-controlled on/off scheme: a software command opens the low-voltage circuit, and a hard-wired wake-up provided by an exposed tailgate switch and a dedicated OBD plug-re-closes it. This allows service technicians or end-of line testers to power-cycle the battery quickly, eliminating repeated manual removal of the battery.