I have one of these, but have never used it as a jump starter, because of the small size mainly it is used to power lights when camping and to charge mobile phones, tablet computersetc. The claim of 20,000mAh is at 5v I think, at 12v capacity is more like 7000mAh or 7Ah. I don't doubt the claim that it will start big diesels.
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If we are going to be altruistic I want to get something out of it
Not sure about those Bob but I have one about the same price from ARB and have only in the last couple of months used it successfully to start a flat battery in two different 4x4's.
I am more than impressed. Just hope if I ever need it for myself it works as well.
I had a cheaper one that didn't work at all on 4x4's even though it was meant to.
Keep Safe on the roads and out there.
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Live Life On Your Terms
DOUGChief One Feather (Losing feathers with age)
TUG.......2014 Holden LT Colorado Twin Cab Ute with Canopy
DEN....... 2014 "Chief" Arrow CV (with some changes)
I have one of these, it will start my 6.5litre powered Patrol from cold without a problem. Cheap insurance and takes up less space than jumper leads which cost $100+ for this size motor.
Amazon is not the only place that sell them. Google is your friend.