1. pdt's Avatar
    I did some experimentation with external batteries for the Surface Pro 4, and thought others out there might benefit since the information available online is hard to sort through. According to the powercfg /batteryreport utility Im getting only 6.25 hours of battery life, even after the 11/2/2015 updates, on my Core i5 256/8 GB SP4, using mostly MS Office and maybe 20% web browsing using Chrome. If you often need to go longer than that between plug-ins, an external battery might be right for you. I happened to have two of them to try out:

    Qi-Infinity Powergrid 34,200 mAh unit, http://www.amazon.com/gp/product/B00...pUvbUpU3280351

    ECEEN 16,000mAh Laptop Power Bank, http://www.amazon.com/Battery-Charge...pUvbUpU3280351

    Neither of these comes with a Surface connector, but you can use the MDW 5.5x2.1 mm to Surface adapter cable which fits both of the external batteries I tested, Amazon.com: MDW Replacement 5.5x2.1mm Dc Charger Adapter Cable for Surface Pro 3 - Small Cable, Portable, Take This Adapter in Your Bag and Charges Your Pro 3 Anywhere That Has a 12v Power Supply: Cell Phones & Accessories

    The SP4 will only draw 2.58A at 12V, so any external battery that can output at least this amperage will work, as long as you can find a suitable connector to the Surface. Both of my batteries can produce at least 4 amps. When off or hibernating, the SP4 will charge from the 10% level to 90% in 2 hours using the AC adapter or either of these batteries. It takes another hour to go from 90% to 100%, so you might not want to wait for it. If the SP4 is in use, I found that it takes 3 hours from 10% to 90% using either AC power or the external batteries.

    Both batteries come with AC adapters that are meant to be used overnight. The Qi took 6.5 hours to go from 0% to 100% and the Eceen took 7.5 hours.

    I found that charging a hibernating SP4 from 10% to 90% took about 1/3 of the Qi. If you are using the SP4 while charging, youll need about 1/2 of the Qi to do it, and you get 3 hours of usage during this time. The SP4 and Qi together give about 23 hours of continuous usage. The Qi battery and cable together weigh 1.9 lb and the Qi AC adapter adds 0.4 lb.

    I found that the Eceen has just enough juice to go from 0 to 100% of the SP4 during hibernation, or 1.25 times from 10% to 90%. If you are using the SP4 while charging, the Eceen will get you from 10% to 75% during about 2.5 hours of usage before it shuts down. The SP4 and Eceen together give about 13 hours of continuous usage. The Eceen plus cable weigh 1.0 lb and its AC adapter adds 0.25 lb. Note that Eceens web site and Amazon both say the Eceen weighs 9.6 oz, but this is false.

    If youre a sometime road warrior like me, you never know where youll go next or when youll see your next working power outlet. If the Qi means not having to carry an extension cord or second device, that makes it an especially good tradeoff for the extra weight and modest cost.
    11-04-2015 04:57 PM
  2. sanshiro's Avatar
    THANKS!! I was actually looking into this and you basically did my homework. :-)
    Ian Mancera likes this.
    11-04-2015 06:37 PM
  3. sanshiro's Avatar
    I was checking out this one. Do you know if this would work?

    http://www.amazon.com/gp/product/B00...pUvbUpU3280504
    11-04-2015 08:05 PM
  4. pdt's Avatar
    Looks like it should work. There are discussions in the Q&A and comments on Amazon about the connectors It looks like the cable I used won't work unless you also get an adapter with a 2.5 mm ID plug If you get this, please let us all know how it goes.
    11-04-2015 08:33 PM
  5. FXi2's Avatar
    On the off chance someone from MS ever reads these threads, it seems like it would be super handy to have a small slice battery that would go around the power connector and up the side a bit, maybe you'd not get tons of juice but if the magnetic attach would hold it and you had a magnetic power input to also push power through/charge it when needed, it would be quite handy for those who are looking for a couple more hours of battery life (think international flying). And if you were totally a road warrior you'd probably have a couple of them. It would make for less Surface book fans maybe a tiny bit, but mostly you'd have options for slightly more battery power on a modular basis (take it when you need it) and you wouldn't be committed to a whole keyboard power system.

    OP: Thank you kindly for being such a timely source of information on a topic I am highly interested in. :)
    11-05-2015 03:26 PM
  6. tennisfan#AC's Avatar
    I took your advice and decided to purchase the Qi. Although it came with a 95% battery level, I am following the instructions to fully charge the battery before using for the first time. I had given up trying to find an external battery to use with my Surface Pro 4. Thanks for the heads up on this topic!!!
    11-06-2015 01:36 PM
  7. WildKarrde's Avatar
    Thanks! I've got the Qi-Infinity™ and adapter headed my way now.

    From your test data, it seems to be about twice as powerful as my two SP2 power covers combined, not bad for half the price!
    11-07-2015 12:39 AM
  8. WildKarrde's Avatar
    So, I'm loving the Qi-Infinity charger! Looks like I can get about 2 full charges out of it on my SP4. My only complaint is that the quality of the adapter is reeeeally sub par, and I'm constantly having to snug back in the port while charging my SP4 and using it. Does anyone know if there is a higher quality magnetic adapter?

    On another note, I've found that you can charge your external battery and the SP4 at the same time as the Qi-Infinity if you're in a pinch and forgot your standard power cable.
    11-11-2015 05:21 PM
  9. new_surfacepro4_user's Avatar
    Thanks for the useful thread. How long do these batteries take to fully charge a SP4 from 0 to 100%? How long does it take to fully charge these batteries?
    11-11-2015 07:06 PM

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