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(Interestingly, the Revo did almost as well as the Antigravity unit in our jump-start tests.) We consider this the power-source performance to be a notable factor, as these units can keep vital devices, such as mobile phones, charged up during a power outage. It provided power for three times as long as the poorest performers, which came from Revo and Noco. The best-performing unit was the Antigravity Batteries XP-10. Where we did see lots of variance was in the units' abilities to charge devices, such as tablets and laptops. When the battery packs were at room temperature, most were able to successfully jump start a frozen car battery.
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The fourth test had the batteries cooled to 0 degrees with the jump starters at room temperature. For the third test, we chilled both the weak batteries and the booster packs down to 0-degrees Fahrenheit. In the first and second test, both the battery and the jumper packs were at room temperature. We purchased 10 mini jump starters, ranging in price from $70 to $125, and ran four separate tests on the car batteries, using different states of charge, working down to completely dead. 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.
BATTERY POWER BOOSTER PORTABLE
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. 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. Most weigh around a pound and are roughly the size of a paperback novel. But the new generation of mini jump starters tested here use compact lithium-ion 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. 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.