But this is a pretty pointless metric when youвЂ™re shopping for a jump starter. Some jump-start packs have only a small error light to warn you of a reverse connection, but the best ones, including our picks, have both a light and an audible alarm that you wonвЂ™t miss.Д¬apacity: Many companies brag about the overall capacity of their jump starters, which they generally list in mAh (milliamp hours) just as the makers of USB battery packs do.

If you screw up, youвЂ™ll get an alert and a chance to try again.

But the reverse-polarity protection built into each of the jump starters we tested confirms that each clamp is on the correct post before completing the circuit. If you confuse them and connect positive to negative and vice versa without that protection, youвЂ™ll get sparks at the connection and potentially damage your carвЂ™s battery or electrical system. When you hook up a jump starter to your battery, you need to connect the positive (+) clamp to the positive post, and then attach the negative (-) clamp to the negative post. Safety features: While most jump starters have a suite of safety circuits to prevent sending more current or voltage than theyвЂ™re designed to handle, reverse-polarity protection is what makes them notably easier to use, especially for people who are concerned about getting the connections wrong.

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