I am a little concerned about the safety of something like that as it has a 12.6v input, so I would assume that it is just 4.2 x 3 - as in there are 3 lipo cells in there in series, without knowing what it has to ballance them, and if there is a low cell cutoff provided I expect that it would just run down once and then on the next charge over volt one of the cells leading to something going fireball in my manbag.
The requirement for 12.6 also means that charging off the car isnt going to happen unless I use an inverter and their wallwart, or else use my hobby charger on it, which I dont even know if it will charge if I dont have a balance lead connected. Also it will probably me more like 10v out once the cells start to discharge.
So what else is there that can provide a reletivly long runtime for a small 12v load? I have found many many packs that deal in 5v for USB devices, and have a decentish looking lipo charger and then a boost converter, not seen anything for 12v however.
Otherwise I may as well just use one of my 3S lipo hobby packs since at least I can charge them without concern.