Between the invention of the self starter and the end of the 20th Century, the best portable car jump starters weren’t something you carried with you. They were heavy lead-acid automotive batteries ...
It did start a 3.0-liter gas engine with a very low battery for us, which is about all we'd expect of it. The Nexpow jump starter uses an 18,000 mAh battery with a claimed shelf life of up to two ...