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Battery Loss When Plugged In?


New Member
Hi Everyone, long time reader, first time poster.

I picked up a SP3 i5 256gb last weekend and have been really enjoying it. Last night I decided to hook it up to my TV and play some XCOM: EW. With the help of the USB fan that others have posted, I was able to play at 720 with medium/low settings (looked great...still working on getting Steam InHome Streaming to work from my rig).

Anyway, after a 2-3 hour session, I picked up the SP3 (was cool to the touch!) and noticed that my battery had actually been drained to about 15%, although I was plugged in. I'll need to test it out again later this week, but curious if anyone else has had a similar experience?


Well-Known Member
That's odd. But having said that I had a similar experience with my Nexus 10 when I had mine. On a low charge (say 35%), I would plug it in to the mains and watch a movie. When done watching the movie, I would invariably find that either the charge level would be the same or it would have dropped. But there was a reason for the this on the N10 - its USB charging system was/ is not good enough to charge the device over and above the power expenditure when watching movies etc. This is also the reason why the N10 takes a long time to charge.

However, I don't think the above applies to the SP3 given its rather efficient charging solution, which is also why I think your experience is odd.


Super Moderator
Staff member
I recall reading that in a couple cases the power plug only charged when connected one way even though the light was on. I believe that was an issue with the charger.


Active Member
Just how big is that USB fan, anyway??? ;)

It is possible that with the fan running and the system utilizing a lot of resources, that you could draw more power than the AC adapter could provide (36W).

I'd try it again, but don't use the fan and see what happens.


New Member
Thanks! The USB fan was actually plugged into the power brick, as I had the USB port on the Surface occupied . Further testing is required ;) .


Active Member
Hmm, even though the fan was on the power brick, it would still be drawing power from the same source as that going to the SP3. In other words, you're still limited to a total of 36W from the power supply, so it doesn't really matter where the load is plugged in as it is still on the DC side of the adapter and it's load would be subtracted from that supplied to the computer.

That's the theory, anyway.