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Surface Pro 3 Third party power adapters from china/hong kong safe?

New2ToMe

Member
Isn't the stability of the voltage important?

Yes, marginally. You need to understand how Volts, Amps and Watts all interact.

Certainly the 12vdc ideally should be regulated, meaning that it is held at 12vdc no matter what demand the device makes of it. That is done these days by one tiny integrated circuit, called, not surprisingly, a Voltage Regulator (VR). Providing the supply to the VR inside the charger is within the VR's design limits, such as, no lower than say 12 volts and no higher than 50 volts the VR will do it's job perfectly. No human needed to verify anything. :)

Given the cost if those VR chips being in the pennies range, it would make no sense for an OEM to not use one. So it can be safely assumed that output the voltage is going to be something like 11.98vdc to 12.03vdc. Just guessing figures but you get what I mean.

Since those halcyon days of Dell laptops spontaneously catching fire, all batteries these days also have their own voltage and current regulators built in. So even if the the charger melted the VR, the battery's own circuitry would leap into the fray. It would either use what it can and keep charging or shut off the supply to the battery entirely. The only thing it cannot do is reach out to the wall wart and pull it out of the outlet. :)

Not saying something could not go wrong and melt the SP2/3 or anything else, just saying that the likelihood is pretty damn slight nowadays.

Given that Lithium Ion Polymer battery guts when exposed to Oxygen will self ignite with some ferocity, all battery and charger manufacturers are very cautious about how the design and build stuff.
 
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kidpiglet

New Member
Thanks for the detailed explanation new2tome. I ended up not buying this particular brand of charger based on reviews of their other chargers (which some were not so positive). I think I will wait until a more slightly more reputable brand releases an affordable one.
 

bluegrass

Well-Known Member
sI have purchased spare MS power/charging pack for all of the Surfaces I own. Yes they are not cheap but they are manufactured by MS for a MS computer. I would only buy one of those $20 chargers to cut of the cable to adapt it to a reasonably priced battery pack that supplies 12 volts at enough amperage to charge or power up my SP3 when I'm in the boonies.
 

tinmandd

New Member
I bought a Yakamoz New Replacement 12V 3A 36W from amazon and did a load regulation test on it. Below is my findings (copy and paste of my Amazon review):

The printed specification on the charger state it's 12V @ 2.58A, not the 3A stated on the description.

Measuring the actual voltage output, it's 12.54V, a little higher than the expected voltage.

There is an white LED indicator similar to the Microsoft OEM charger, but the LED never turns off. So, unlike the OEM charger, which only turns on when plugged into the Surface Pro 3, the LED is always on.

The actual brick is warmer than the OEM charger.

The Surface Pro 3 works fine with it. Plug it in and the Surface Pro 3 indicates on AC and charging.

Update 1/29/15
After using it for a while, the voltage reading is now 12.38V, not the initial 12.54V.

The load regulation test was ran on the AC adapter. The equipment used is an Agilent 2902A SMU acting as a DC current load. The max current the SMU could sink for 12V is 1.5A.

mA V
0 12.39069
200 12.35829
400 12.33055
600 12.30292
800 12.27537
1000 12.25577
1200 12.23485
1400 12.21644

Assuming the voltage drop is linear, at the maximum current stated on the AC adapter (2.58A), the expected voltage would be 12.125V.

Base on this result, it appears the AC adapter was set to have a higher voltage at no load condition such that when a full load condition, the voltage will still be 12V.
 

Markos

New Member
I want to buy a charger. I have one of the following 3 in mind. What do you think about it?

aliexpress.com/item/32280694994.html
2015-High-Quality-12V-2-58A-30W-EU-Plug-AC-Wall-Charger-Adapter-Power-Supply-For.jpg_640x640.jpg


aliexpress.com/item/32280694994.html
12V-3A-Wall-AC-Charger-Power-Adapter-Cable-For-Microsoft-Surface-Pro-3-Tablet-PC-Free.jpg_640x640.jpg


aliexpress.com/item/32351975382.html
Magnetic-Power-Charger-AC-Adapter-for-Microsoft-Surface-PRO-3-12-Inch-Tablet-Special-Designed-with.jpg_640x640.jpg


I like the last one because of the USB charger. A bit like the original charger. But I prefer just a good (cheap ;) ) charger. Any experiences?
 
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