Milwaukee 18v Power Source

I have been playing around with the M18 power source, this is obviously only of interest to those tradesman or serious DIYers who own Milwaukee kit.
http://tapatalk.imageshack.com/v2/15...6c4073c08f.jpg
I currently have a full charged 4ah battery and I have half charged my Samsung S4 while I have been using it in a couple of hours. The 18v battery is still on 4 bars though these indicators are only really a rough guide and dont give a precise indication of performance. People are reporting online up to 6 full cycle charges of a completely dead smart phone.

The USB is a 2.1A also which is standard from most main powers chargers Ive seen. http://tapatalk.imageshack.com/v2/15...76fa8da84f.jpg
This also has the standard 12v DC plug which will apparently give me 18hrs of heat from my Milwaukee heated jacket. http://tapatalk.imageshack.com/v2/15...7677b89380.jpg

The downside is obviously the weight at about 800gms and the fact you have to invest in a cordless tool kit to make this a viable solution. Im kicking myself I never purchased one sooner for the remote sites I sometimes find myself in and not just to run a GPS app from my phone.