External Battery for Surface Pro?

This brings up another question ... will this be able to get buy a TSA check point? =)

Seriously though ... good job guys.

 

I wish I had found this post earlier... I had taken a similar approach, but found "less than desirable" results... Here's what I tried. Goal was to have a "travel adapter" that could hook up to AC, my LiPo battery, or even a car's cigarette lighter (but I never made that cable).
1) hack off the end of a perfect good Surface power adapter
2) ignore the small-gauge control wires. Focus on the coaxed silver and red conductors. Solder those to a male DC barrel power connector so it can then be plugged in to the various power sources.
3) Solder a female DC barrel power connector to the other end of the surface power connector: the AC power source.
4) solder another female barrel DC power connector to a cable to connect to my 12V LiPo battery I had (used with RC cars/ planes): the DC power source.

Now, on to testing... regardless of how I connected this setup, the surface pro never recognized the connected power - my multi-meter verified the rigged power supply exactly matched the factory power supply (except the blue/ yellow control wires).

When I connected the orig power supply, win8 did show the power was connected. When I disconnected power and ran from battery, the power meter never went below 100%. This is really strange - never seen that before - nothing like some added fun when you think you've screwed up the wife's new computer... It finally showed less than 100% when the battery died! To add to the mystery, when I recharged the surface back to 100% using the orig power supply, everything is back to normal and battery meter works fine.

BTW, when I soldered the hacked power supply back together (connecting all 4 wires), the power supply works fine.

Sooooo, what I had deduced is that yellow/ blue control wires DO matter in some way. BUT, I'm not exactly sure now that I've read that others have SUCCESSFULLY rigged this up. To exasterbate confusion, I did a quick mock up with the LiPo battery, just twisting the power wires together, and tested that - the win8 meter did not show the charging "lightning bolt" but it did indeed charge the battery.

I'm now tempted to try out this setup again - hopefully in time for our Italy trip... I think I'll start by eliminating the barrel connectors and hard wiring things. But, I'm not clear on how to handle the yellow/ blue control wires - BjornB: can you provide details on the resistor setup you used?

Thanks!

 

Here is my setup:

It consists of a Surface RT charger, cable cut and modified with powerpole connectors. The external battery also use pp connector and is set to 12V (10 - 19V selectable).

On the charger (AC) side I have connected red, black and blue to connectors (I did not have a blue pp housing, the red in the middle is plus and the red on the end is the blue wire). The yellow cable is soldered to red with 500ohms in between (resistor in series). This activates the RT charger so I can use it as a small generic 12V supply.
On the Surface side I have connected red, black and blue to connectors - the blue for enabling charger detection - i.e. current limiting when the RT charger is being used to charge the Surface Pro.
On the Surface side of the cable I have also connected yellow to red with a 6k ohm resistor in between. This activates the white led on the magnetic plug (with 6kohm the led is a bit fainter than normal, but seems to work fine).
The external battery gives me 12V (in reality ~12.4V), and is connected to the Surface cable leaving the blue cable unconnected.

External battery in use:


Also shown in other pictures in this thread and above is a DC volt/amp/powermeter connected inline when I want to monitor the charging, product:
Digital DC Ammeter, Amp Hour Meter, Watt Hour Meter
Can be bought here:
Watt's Up Meter - DC Inline

 

I know it's not too portable (3.5lbs), but my vagabond charges my surface pro without any issues

Paul C. Buff - Vagabond Portable Power

I use to power monolights outdoors

 

<<...my vagabond charges my surface pro without any issues...>>

dark: Funny you should mention this. I have occasionally looked at Buff's products in the past, especially the Vagabond II (self-contained high-capacity battery and DC-AC inverter), as a potential solution for the enduring problem of DC adapter tips that don't fit my new tablet. However, as you allude, I've always been put off by the weight of the unit and the suspicion that it was producing a modified sine wave output rather than a true sine wave output. (And in both cases, there is the inevitability of a lot of electromagnetic switching noise.)

Now I see that the Vagabond is explicitly labeled as a True Sine Wave inverter; that's a good thing, in my opinion. I might take another look at Buff's products under this circumstance.

When you use your Vagabond, do you notice any EMI problems? If you bring your Pro closer to the unit, is the touch behavior OK? (How about an AM radio?)

PS: If you are interested in inverters, the Don Rowe site offers a reasonable selection of brands (Samlex, Xantrex...) in low to mid capacities (150 W, 400 W) at reasonable prices:

http://www.donrowe.com/inverters/puresine.html?gclid=CKSNkLe_kLYCFQjhQgod8WwA4w

(I have no connection to Don Rowe.)

 

Based on the post by member darktiger, I did a bit of research on Paul Buff's new Vagabond Mini - Lithium (See: Paul C. Buff - Vagabond Portable Power ).

The unit is approximately 3" x 4" x 8" and weighs in at ~3.5 lb. It has an integrated, user-swap-able 130 Whr battery and the Vagabond comes with a separate, 3-hour AC adapter / charger. Buff advertises that the "discharged battery can be safely stored for months at a time without damage; no sulfating or &#8220;memory effect&#8221;..." Extra batteries are also available and can be charged when dismounted from the unit. The Vagabond Mini - Lithium sells for $240. Extra Batteries will set you back $90.

The Vagabond Mini will provide 120VAC at 1A continuously. Based on the power measurements discussed in this thread:

http://forum.tabletpcreview.com/mic...pro-power-consumption-through-ac-adapter.html

...the Mini can provide enough power to run and recharge the Surface Pro when you are away from a normal AC outlet. Note that the Vagabond also provides a 5V, 0.5A USB charging port.

Considering its form factor and size, I speculate that the Vagabond Mini is based on the BA Power Model B-12S120, a true sine wave inverter. the B-12S120 is spec'ed as providing a 115VAC (±3%) output at up to 120W steady-state (that is, about 1A steady-state output current). Total harmonic distortion (a measure of the purity of the sine wave output) is pretty good at less than 3%. Conversion efficiency is a bit low at ~85% (other sine wave inverters range from 88% to "over 90%"). The implication of this last performance metric is that the 130Whrs of input power provides ~110 Whrs of AC output (although that is still a health amount). In the absence of an actual test, it seems reasonable to assume that the Vagabond Mini ought to be able to recharge the Surface Pro's 42Whr battery about twice. Although the case appears to be plastic, some simple sheet-metal internal shielding should adequately control radiated electromagnetic interference.

However, the downside to all of this is that you have lug around not just the Vagabond, but the Pro's AC adapter as well. Maybe the fact that the Vagabond can be used with any low-power AC appliance makes up, in part, for its weight and bulk...???

(Images courtesy of PaulCBuff.com site)

 

See a user review of the Vagabond Mini here:

http://forum.tabletpcreview.com/acc...ini-self-powered-ac-inverter-user-review.html

 

When you use your Vagabond, do you notice any EMI problems? If you bring your Pro closer to the unit, is the touch behavior OK? (How about an AM radio?)

I placed my surface pro on top of the Vagabond Mini and touch works fine.... I do not have a AM/FM Radio laying around,.... So I cannot test that..... But I have used it to charge iPads, iPhones, Macbook Pro 15"... I even used it to blow up outdoor inflatable pools, power fans/blowers, air mattresses.. etc.. it is a useful device...

 

<<...I placed my surface pro on top of the Vagabond Mini and touch works fine...>>

dark: Thanks for checking. I confirmed the same thing using my RT...

 

Help! My dad was my resident geek and he passed away a few years back...I am just a "wanna-be geek" and nurse. I bought a surface pro and frequently take long trips, so was hoping to use my external battery that I purchaed for my macbook. I bought an extra charger and sacrificed the tip and tried to simply wire it to the end where I cut off the macbook connector....that didnt work, so I followed your thread and purchased the hyperjuice magic box, but must have done something wrong because it didn't work- and it sounds like it has been successful. I twisted the blue and yellow wires in with the negative and put the red (+) in the first slot. I am baffled! I also have an APC notebook battery, but not sure even where to start with that. My mac battery appears to have enough output (dc15v=4.3A) Is there another way to connect it??