I recently purchased a Cyntur Jumper Pack Mini for use while traveling CONUS and OCONUS. Just tested it on two V-8 engine up-armored Toyota Land Cruisers that recently returned from Afghanistan with dead batteries. The Jumper Pack Mini successfully started both vehicles in less than 4 seconds, one right after the other. It can jump large V-8 engines and anything smaller.
It will re-charge a phone 3-6 times and a tablet 1-3 times before the device needs re-charged itself. A full charge lasts 1 year in the Lithium Ion battery. It can be re-charged via an AC wall socket, or even inside a running vehicle on the go, using a power inverter inside the vehicle. $99.95...not a bad pricepoint for some piece of mind and not being caught dead in the water far away from assistance. They have another model coming out soon, the Jumper Pack Pro, that will be able to handle diesel motors.
The Jumper Pack Mini also has an integral flashlight, which can also be switched over to flash SOS.
So far, I'm pretty impressed with the power the company has packed into such a small package.
It is small enough that it can be carried in a carry-on bag, which is TSA compliant. It cannot be carried in checked luggage.
Here's a link for anyone interested: