The lithium-ion batteries in portable booster packs don’t like to sit around unused, which makes them unreliable, according, to Australia-based RescueMate. That’s not the case with the company’s Kanga500 Super Capacitor Jump Starter because the product contains no batteries. As a super capacitor, it actually draws what little power remains in your car battery — in 90 seconds — and then uses it to boost your vehicle. This sounds impossible, but it works because super capacitors absorb, hold and discharged electricity differently than batteries: They’re much faster. The Kanga500 can boost vehicles up to 5.0 liters of displacement — 500,000 times — and costs $200 from Home Depot. The higher-capacity RM750 is for engines up to 8.0 liters of displacement, but you’ll likely have to source one from the manufacturer at http://www.rescue-mate.com.au.