External Battery for Surface Pro?

Discussion in 'Microsoft' started by dgeffs, Feb 12, 2013.

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  1. chandlercv

    chandlercv Pen Pal - Newbie

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    The 10.5V seems to be doing well. It's slowly charging, even as I'm using it. There does seems to be some noise, still, but I'm less concerned since I'm undervolting. I will try putting the capacitor in tomorrow and see if that does anything for the noise.

    Thanks for all the help!
     
  2. natemiller82

    natemiller82 Pen Pal - Newbie

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    Just got a custom Mike Gyver cable that plugs my surface pro into my xpal 18000. It works great so far. It's listed on his website as the 3.4 x 1.3 surface cable.

    Sent from my SCH-I535 using Tapatalk 4 Beta
     
  3. Kazuma

    Kazuma Pen Pal - Newbie

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    Hey!
    Im new around here. I am planning on grabbing a surface pro and ima take it with me to a long 16 hour flight from canada to manila. And i came across a project on kick starter about a portable battery pack that you can recharge using sunlight.
    SunStash Portable Solar Power Charger For Gadgets & Laptops by Don Cayelli — Kickstarter

    I was thinking i was i might be able to use it to charge my surface pro while in the plane, but then this power cable problem appeared. That sunstash only includes tips for laptops. And i came across with this product earlier,
    Microsoft Surface External Battery & Car Adapter Charger
    Its a portable battery pack for surface pro and rt. I noticed that they are using the same battery banks. So im just wondering, if i buy the surface pro car adapter which includes the power cable for the surface pro, do you guys think i can use it to my sunstash? All i need is the stupid power cable for my surface pro.
     
  4. den.peder

    den.peder Pen Pal - Newbie

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    I have read many of these replies and have to comment further on a few who have recognized that the surface RT uses a lithium ion battery and the charging of these batteries does require strict control. That circuit board is extremely important. I wish I had the answers that some have raised as to exactly what does it do.
    Having said all that, I too need a charger for my RT that will function with a 12v supply. As one person said, if you could find the point in the circuit board where the 110 creates 12 or so volts, we could probably then tap in and use that control which is needed for those lithium ion batteries. I strongly suggest that you do not try to connect 12v to the RT as you will eventually destroy the battery and maybe cause a fire.
    Looking forward to some answers.
     
  5. Steve S

    Steve S Pen Pro - Senior Member Super Moderator

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    <<... I wish I had the answers that some have raised as to exactly what does it do...>>

    den: Interestingly, after initial concerns about the battery life of my Surface Pro, I have found that it isn't a problem for my use case. As long as I remember to put the Pro to sleep in between daily intervals of use, the battery life is adequate. However, I do understand that others may still have the need for an additional source of portable power. Some observations from this thread:

    <> Based on the lack of additional comment, it would appear that the external battery mod (member JanAWD, Post # 11) mentioned below may work OK. He has not mentioned having his Surface Pro consumed by a Lithium fire!

    <> Similarly, bjornb's mods (Post # 21 & # 33) have apparently behaved OK, too.

    <> Same comment for the MCT external battery (Kazuma, Post # 63).

    The bottom line is that it appears that there are at least a few viable options to extend the operating time on a Surface Pro. Although modifying a Surface AC adapter might be the most bullet-proof aproach, it doesn't appear to be necessary...
     
  6. bjornb

    bjornb Pen Pal - Newbie

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    The RT and Pro is supplied with 12V. Charging regulation for the li-ion cells is done inside the unit regardless of the external power supply.
    When charge is at 100% the voltage is still 12V (but there is almost no current). This is my modified RT adapter connected to my Pro when fully charged and in standby/sleep:
    2013-08-12 10.17.33.jpg

    I've been using my solution with a 12V battery source for some time now and it works well. I have also connected my modified Surface connector directly to a 12V SLA (lead acid) battery bank in a sailboat (I disconnected it before we started the engine, since the charging voltage is closer to 14V).
     
    Last edited: Aug 12, 2013
  7. den.peder

    den.peder Pen Pal - Newbie

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  8. Steve S

    Steve S Pen Pro - Senior Member Super Moderator

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    <<...Do you think that 14.2v would be too much...>>

    ...Open circuit voltage (i.e., battery not connected to anything) and voltage under load (battery connected to something) are two different things. If the voltage under load is ~12 VDC or less, then all will be OK. If it is substantially more than 12VDC (let's say more than 10% or 1.2VDC), then there might be an increase in battery life issues over time. The difference between open circuit voltage and voltage under load is a function of the "stiffness" of the power source, which is in turn a function of how readily the power source can supply the current demanded by the load. When a battery is the power source, the current limit is typically established by the battery internal geometry and its chemistry (lead acid, nickel metal hydride, lithium manganese, etc.). Taking all things into account, my guess would be that your Li-Ion (?) power source batteries would hold the voltage up reasonably well, and so you should be concerned about higher-than-normal voltages. (Small voltage mismatches like this are a real PIA for the designer, but sometimes you just have to bite the bullet and design for it.)
     
  9. Bronsky

    Bronsky Wait and Hope. Senior Member

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    Using it as a chart plotter? I'm just finishing up a refit of a Telstar 26 Trimaran and would like to use my Q552 as a chart plotter next season.
     
  10. bjornb

    bjornb Pen Pal - Newbie

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    The charging/supply circuits inside the Surface has an operating range for the input voltage. This range is unknown to us (I did try to look at the detailed tear down images at ifixit.com, and found some of the chargings circuits - it is referenced earlier in this thread, but I was unable to conclude at anything at the time).
    I agree with Steve above, 10% higher should be fine, and I have exposed mine to that voltage without problems so far. I wouldnt be suprised if 14.2V is also within the acceptable input range, but since we dont know for sure I havent risked it.

    Some say its fine - the first part of the post below is about testing an ebay surface car adapter (with no regulation), last part about an aftermarket product and voltage:
    External Battery Pack Option - Page 10

    Aftermarket product here:
    Microsoft Surface External Battery & Car Adapter Charger

    No, just surfing the web and watching videos stored locally at this time.
     
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