The MYCHANIC Smart Jumper Cables ($25) include the brilliant feature of reverse polarity protection.
Live positive to dead positive, live negative to ground—that's the car-jumping wisdom that's ingrained in your memory. But if you haven’t jumped a car since Pogs were a thing, you’ll be excused for a brief lapse, which is exactly why you need this protection. With the MYCHANIC cables, instead of a blinding spark (followed by some creative swearing), crossed wires result in a beep and a blinking light.
A voltage meter built into the 12-foot, six-gauge cables detects incorrect voltage (less than zero volts) and triggers the reverse polarity alarm, stopping the flow of electrons. The voltage meter also reads the charge on your battery to confirm that your battery is the problem, not your starter or alternator. Fully charged, with the engine off, a healthy battery will register between 12.4 and 12.7 volts