REVIVING A dead battery used to mean having a pair of jumper cables on hand and finding a good Samaritan with another vehicle to jump-start your car. These days you can do it all on your own.

A rechargeable battery pack has enough juice to kick-start a car’s battery by hooking it up to the terminals. They are available from several companies, including Gooloo, Scosche and Noco. These devices are about the size of a paperback book and start at around $100. Bonus: They often have connections that recharge a smartphone too.

You can also charge your battery from inside your car. Some chargers or adapters plug into a car’s 12-volt outlet (formerly known as the cigarette lighter). It can be safer than popping the hood and standing outside. —John R. Quain