First it was Apple with their MagSafe, 30-Pin, and Lightning adapters. Now Microsoft (Surface) and Lenovo (X1 Carbon) are making their own proprietary charging connectors. This is great if you are sitting next to an AC outlet, but not so great if you are trying to charge your new Surface on the road from a car, portable battery or solar charger.

surface charger

With the help of a couple of kind customers, we have now built a few custom Microsoft Surface charging cables. Here’s what we did.

Please proceed, only if you are comfortable with hacking electronics. Voltaic takes no responsibility for any charging cables created by our customers.

Buy a spare Surface charger. You can pick up the 24-Watt charger from Microsoft. The 48-W version isn’t necessary even if you have the Pro since we’re cutting off the transformer anyway. We’ve also seen some (untested) replicas on eBay.

Cut open the charger to reveal the four wires. Testing with a multimeter indicates the red carries positive 12V, whereas black, yellow, and blue were 0V. Based on standards, we assumed black to be the negative.

We’re not sure what purpose the other two wires serve, but they appear to be unnecessary for charging – if anyone knows, let us know. A few readers have chimed in on the purpose of the yellow and blue wires: the blue wire appears to be for charger detection (so that the Surface does not try to draw more than the charger can supply). It’s not necessary for our V60 battery, which supplies 4A, more than the Surface draws. The yellow wire is for illuminating the plug’s charge LED (and can be connected to red through a resistor – 6K Ohm works well according to this thread). We’ll hopefully be able to check this out soon. Thanks for your input, guys!

Solder the positive and negative on the Surface charger to the positive and negative on a Voltaic cable (if you’re doing this at home, use our 5525 Wire). We trimmed back the white and blue wires so as to insulate them and did not use them. Cover with heat shrink tubing.

Now, connect to the Voltaic V60 Laptop Battery at 12V and charge away. The Microsoft Surface battery size varies from 31.5 (RT) to 42 Watt hours (Pro), so you’ll get more than a full charge on the RT and a full charge on the Pro.

More details on charge times can be found on our Solar Charger for Tablets Guide.

30 Responses to Portable Charger for Microsoft Surface

  1. Shane says:

    Can’t I just use the voltaic female car charger adapter with the male car charger adapter that microsoft makes. It’s might be a little more expensive but it won’t require hacking.

  2. John says:

    Sooo could one use this

    http://www.ebay.com/itm/5W-USB-DC-5V-to-12V-Step-Up-Boost-Module-Moter-Wireless-controller-Solar-Charger-/271176652645?pt=LH_DefaultDomain_0&hash=item3f23635765

    like mentioned above and then hook up the magnetic charger to that to make a USB charger?? In other words the cable would have a USB on one end and then the magnetic adapter the other.

  3. Martin Foss says:

    G’day, THANK-YOU SO MUCH I threw a coat on the charger. It overheated and died. I rumbled through my ‘stuff’ and found a 12v power supply. I used the RED wire as “+” and I used, what looked like a shield, for “-”. I was stuffed w/o a charger and now it I got a back-up until I get a new one.

    Thanks Heaps,
    Omerde

  4. Adam Hiner says:

    I am trying to do this with the Turcom M9000. The rated outputs are DC 15V-4A/16V-4A/18V&18.5V-3.3A/19V&19.5V-3.16A/20V-3A/USB 5V-1A.

    Will this work with the microsoft pro? There is no 12V listed. Will this still work? Will it damage the Surface Pro because of the extra voltage?

    • admin says:

      My guess would be that it probably wouldn’t damage the Microsoft Pro when you use the 15V setting, although it simply may not work. We haven’t tested it though and it would certainly be safer to use a battery with a 12V output.

  5. Ray says:

    Any chance to hack this with a USB cable so you can charge via USB? Or does the difference in voltage prevent it from working?

    The scenario I have in mind is then being able to charge the Surface with one of those portable external batteries (often have two USB outputs: 5V/1A and 5V/2A)

  6. Justin says:

    I assume you could use a standard 12V lead-acid car battery, unregulated? But if the battery is charging (so the voltage across the terminals is more like 13V) then it would be best to have a regulator?

  7. TGMcCallie@epbfi.com says:

    Here is charging attachment for Surface which is already constructed properly to work from
    dc outlet in power bank.
    Go to EBay and search for charger cable for
    Surface and you will find it. I have one ordered from Honk Kong. It will plug into your
    surface and the other end will plug into any DC outlet from Power Supply.

  8. Joseph says:

    Jeff,

    Do you charge for the modification?
    Also, what batteries would be safe to use with this modification? Will any external battery work, or do I need specific ratings?

    Thanks

  9. Esteriel says:

    This may be a bit off topic, but you seem to know your way around the Surface Pro battery charging components, so I hope you can help. I charged the Pro with no problems when I bought it a week ago, but now the battery needs recharging and I can’t make it work. There is power getting to the transformer and 12V power getting from there to the magnetic connector, but that seems to be where it stops. I have no LED lighting up, and the battery has now run out completely and the Pro is dead. The contacts don’t seem damaged, loose or dirty and I don’t know what else to try. Can you suggest anything else, or will I have to try to get support from Microsoft? I don’t mind buying another charger, but I’m not sure that is where the problem is.

    • admin says:

      I would go to Microsoft. Based on what you’re saying it is either an issue with the connection inside the Surface itself or potentially there is something off in the Voltage of the pin configuration. We can look at this tomorrow as we don’t have one on hand right now, but are getting one shortly.

  10. Aaron says:

    I cut up an extra Surface Pro Charger cord and found the Red Wire, Blue and white and there were two grounds neither of which were in a black shielding? One ground was small and located in the center of all the wires and the other was wrapped around all the wires. I connected all the grounds (small and large) to the black on the Voltaic wire and the red to the red on the voltaic wire (left the blue and white loose) when plugged in got the charging symbol on my Surface Pro. I think the Surface Pro cable is different from the RT. I hope combining the two grounds does not mess anything up?

    • tommy says:

      That is interesting – we’ve only seen the RT chargers so far, so we can’t say we’ve seen what you’re describing. If it works, that’s certainly a good sign, but we’re not sure what each of those two conductors may be.

  11. rankit says:

    hi,

    Is there anyways I can buy it from you. appreciate as I am having issues with my surface pro charging I am out. Thanks

    Regds,
    Rankit

    • admin says:

      Hi Rankit,

      We don’t have a supply of Surface cables. If you send us a Surface Pro cable, we can hack it for you and send it back to you. Send an email to support@voltaicsystems.com and we can let you know the delivery address. Thanks, Jeff

  12. Ryu Ran says:

    Cool! I bought Surface Pro Charger from HK for 30$, and I wonder if this method works for mine.
    It has no LED and is slightly different from the official one.

    • admin says:

      Hi Ryu,

      We’ve done tests with the knock-off ones and they did work fine (though no LED as you say). The quality of workmanship on them weren’t very good so we aren’t going to strongly recommend them, but we think you can probably go ahead and make the adapter. /jeff

  13. Henrik Johansson says:

    Hey you guys and Girls!
    Thanks a million for this post! I’ve sent you an RT-charger and will get help with this, I can’t tell you how greatful I am for this!
    I’ll send you some pics once I receive it back, I just got my V60-battery today, so I can’t wait to try this out on my Surface Pro! Thanks again and greets from Sweden! :-D

  14. BB says:

    About the other wires:
    The white (/yellow) wire is for the white charge LED on the plug. The blue wire is used for charger detection. If you use the RT charger on the Surface Pro the Pro will detect the smaller RT charger and limit the current to 2A. If your external battery is able to provide the same current as the Pro charger (3.6A) the blue line seems to be unnecessary.

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