I've tried a few and you have to take most sellers blurb with a pinch of salt.
I'm sure some of these units will start a 900cc Corsa but the bigger stuff soon defeats them.
When my 4/4 expired with a completely flat battery recently a friend got it started with a pack that he'd picked up for £40 in Lidl. It was about the size of a USB hub and was only half charged itself yet it put enough oomph into my battery for it to start itself the next time. I was very impressed, I'm just waiting to see one that cheap.
~iw
