For anyone looking to purchase this Zitay - I have had a further look. The output is 10.8V which is within the required range and it is rated at 6800mAH, which is more than enough. It is not 2A. So you get 75Wh - for the 6k that is about 3 hours of run time, and more for the 4k. The current price is 85USD . Some people will appreciate how it mounts and how discrete it is.