It used to be that a set of jumper cables (and an obliging fellow motorist) or a call for roadside assistance was needed to jump-start a car, but a convenient alternative has recently hit the market: The mini jump starter. These micro-sized battery packs are small enough to fit in your glovebox and powerful enough to jolt your car back to life.
Battery jump starters are nothing new, but until now, ones that worked well in our tests were sized like a hardcover dictionary powered by heavy lead-acid batteries. While great for car dealers and auto recovery services, these traditional booster packs are too bulky to carry as part of a car emergency kit. But the new generation of mini jump starters tested here use compact lithium-ion batteries. Most weigh around a pound and are roughly the size of a paperback novel. The 10 units we tested had an average price of about $90, making them only slightly more expensive than traditional car battery boosters--and a heck of a lot easier to carry.
In addition to jump-starting, these units can also be used to recharge portable devices, such as mobile phones and tablets--a function that makes them a useful part of a home emergency kit, as well. All of the units we tested had at least one built-in USB port, as well as a flashlight, and some had connectors to charge certain types of laptops.
