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charge with cellphone charger?


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I'd like to point out that 28.4Wh is not the same as 28400mAh. The LimeFuel pack is 20000mAh/74Wh (3.70v battery) and my PowerAdd Pilot x6 is 20800mAh/77Wh (3.70v battery).

As a comparison, the iPad Air 2 is 7324mAh/27.62Wh (3.76v battery) and the Surface Pro 3 is 5676mAh/42Wh at 7.4v. A close competitor to the Surface 3 (Asus T100) is 8060mAh/31Wr, which would give it a 3.846v battery. The Surface 3 should be between 3.7 - 3.9v, but if we use the same voltage as the T100,

Since we don't know the voltage of the Surface 3, we can't find out the mAh. I would give the Surface 3 a 7384Mah battery if it was the same voltage as the T100. (the range should be 7282mAh @ 3.9v - 7676mAh @ 3.7v)

Here is the math if anyone is wondering
(Wh / voltage) * 1000 = mAh
or if we had the mAh:
(mAh / 1000) x voltage = Wh
Wh / (mAh / 1000) = voltage

tl;dr: A 20000mAh external battery should be able to charge the Surface 3 at least twice.
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The magnetic cable to me is the best and to me one of the biggest disadvantages of the S3. I do not know how many times this feature has saved my SP3 from falling.
To me it's the opposite; the proprietary connection is one of the the biggest disadvantage of the SP and MBA on the road. The magnetic cable on my SP and MBA has never saved either, and my Android tablets, used plugged in at desk, on the bed and couch have never been damaged by a pulled cord.


According to NotebookCheck the Surface 3 battery is 28400 mwh (28.4 wh).
This LimeFuel pack should give you an additional 5-7 hours.

Edit: This is wrong ... see below ... it's even better.

For $30 that looks good and it's a bit slimmer than the OEM charger so it should fit a little better in a slim tote bag than the power brick.
It would be really convenient to be able to put the Surface 3 in a tote bag and charge it between uses without being tethered to a wall outlet as long as it's possible to route the cable through the bag and keep it plugged into the micro usb port without bending connectors.
You just have to recharge the battery pack for the next day when you get back home or to your hotel.

Even though the Surface 3 might last all day with light usage, if you do things that stress the CPU, such as run long presentations over Miracast wireless video to a large screen TV or even do long presentations with an HDMI cable to a projector, the battery life of the Surface 3 will probably be cut way down.

This external battery pack says it can charge at up to 2.1 amps. That would be slower than using the OEM charger plugged into an outlet, but if the Surface 3 is powered off, I would expect that it would still charge pretty quickly.