It charges cell phones, but it also jump starts cars.

[rfranzq]

Originally Posted by GadgetKen

The big (and very heavy) ones really will start a car or a tractor. They have a sealed lead acid gel cell inside. Issue can be when the gel cell can't be recharged anymore...you need to get a replacement that fits or buy a complete new unit. In the US, MCM Electronics and some other vendors carry compatible gel cells.

The ones I am talking about are a little bigger than smart phones and use Lithium-Ion batteries.