Many of us carry a set of thick, bulky jumper cables or possibly one of those heavy battery booster packs in the trunk of our vehicles for recharging a dead starter battery. That might be no longer necessary if you own a JunoJumper. This handy little power source is about the size of a smart phone and weighs only seven ounces. It can juice up your phone or tablet and apparently jumpstart a 12-volt car battery in short order (with 300 amps of output it’s designed for four- and six-cylinder-powered vehicles only). JunoJumper charges via USB port or 12-volt lighter socket. Pick one up directly from the manufacturer for $100, including battery connectors, at www.junopower.com.