First post here, but have had the Pro since day one and have been checking this (very helpful) thread often because I love my external batteries and have wanted to use one with my surface as that's one of only two issues I have with it (the other being I wish it had a little more RAM because I came from an x230t with 16GB). Although I honestly don't consider battery life much of an "issue" as opposed to tech limitation given the size of the machine vs the power, it actually does quite good IMO.
Anyway, I had never stripped a wire in my life, much less used a solder iron, but after watching a quick how-to on youtube decided to try it. I bought a $10 solder iron at wally world, and attached the surface adapter from a cheapo third party charger I already had with the DC cable that plugs into my Anker Astro 3 battery. The Astro 3 is 10,000mah with a 12v 2a output. However, I did not have the same luck as the guy above me, because when plugged into the Astro 3, my Pro will charge for maybe 3 seconds and the battery will shut down.
BUT, I got one of the Anker Astro Pro2 20,000mah packs (as mentioned above) in today and I was happy to see that my first solder job wasn't a failure because this more powerful battery charges it just fine. I wonder why my 10,000 pack shuts off? In my reading I learned that the MS charger has four wires, with one that identifies the charger output so the Surface doesn't try to pull too much. My cheapo charger only had two wires, red (+) and white (-), so I figured maybe the lesser battery was shutting down because the Surface was trying to pull too many amps? But the charger when it was intact worked fine. To the guy above with the 8200mah pack, did you use an official MS charger for your's?
