I have much the same thing for my cellphones.
it is a 26,500 mAH battery pack.
Takes 2 or 3 days to charge it up, but once charged up, it will recharge a dead cellphone about 6 times.
I carry it with me for long day trips where we don't have anyway to recharge the phones. has been a life saver for me.
e.g., got off the bike at a Rest Stop many times, just need to rest a while, eat something, and cruise the Internet to get updates, emails, Facebook, etc.
The power pack is great for keeping the phone at full charge while I am idle.
it is not something to carry in your coat pocket, too damn heavy.
I have seen folks use those Jumper Packs to start up lawn tractors, and once saw it used to jump a car battery. But to think it will run a vehicle for more than a few minutes, or couple of hours? I doubt it.