External Battery Pack Option

[curney]

No certification is listed on the charger. The blown fuse is a "F3/L250V". Unfortunately, this particular charger is most likely only capable of supporting the "RT".

Also, the website now lists this charger as "Microsoft Surface RT Car adapter" instead of the "Pro". Probably a good move so that future buyers are not disappointed. However, the magnetic cable is nice and is a separate detachable cable from the car charger unit. It would be good to have for an external battery pack.

I received quick response from the seller and great support. We all know "accessories" for the Pro are slow to come to market.

I bought a Rt car charger and the pro blew the fuse....

 

[Wayne Orwig]

How much current is it certified to provide?

If I recall, it had a 2 amp fuse. Using the cable and a lab power supply, I found that the PRO pulls just under 4 amps. Using the lab power supply, and a larger fuse, I found that the 12 volt adapter was managing to pass only about 3 amps. But the spring used to retain the fuse got extremely hot and started to melt the plastic. In other words, the design was so weak that the spring for the fuse was almost a fuse itself. Passing the <2 amps for the RT is even a struggle for it.

But I got my cable.

 

[heed]

Quick question: I have a 3rd party power adapter that doesn't work quite right. I also have a portable battery pack that outputs 12V. I also have a degree in EE that I haven't used in 20 years . do I need to put something in line to limit current? If so, what?

 

[ArnoldC]

Quick question: I have a 3rd party power adapter that doesn't work quite right. I also have a portable battery pack that outputs 12V. I also have a degree in EE that I haven't used in 20 years . do I need to put something in line to limit current? If so, what? ��

No. Make sure that the power adapter has the *capability* to supply the current to be drawn by the Surface, otherwise you'll end up like in the previous post.

 

[Garyjk]

on a related note, if you want to get a report on your battery:

go to a elevated command prompt and then type the following:

powercfg /batteryreport
press enter

an extensive html file will be created. just look at the path in the return message and open it up.

 

[Wayne Orwig]

Quick question: I have a 3rd party power adapter that doesn't work quite right. I also have a portable battery pack that outputs 12V. I also have a degree in EE that I haven't used in 20 years . do I need to put something in line to limit current? If so, what?

Are you saying that you are going to steal the cables from the adapter and connect it to this battery pack?

If so, we need more details on the battery pack. The voltage needs to be reasonably well regulated. If it goes too far above 12V, it may cause damage. Nobody knows how high is safe, so I would make sure it was less than 13V. I did some experiments and found that below 12V, at around 10.5, the Surface simply stops charging.

Also keep in mind that the Surface is of course using switch mode supplies. Thus, it tends to be about watts. So at 12.5V, it may pull around 3 amps. at 12V that creeps up to 3.125A, and at 11V it would be about 3.4 amps. The point being, if the battery pack is going dead, the current may actually go up as it dies. Where this is an issue is if your battery pack has a regulator. If the regulator can't keep up, the voltage drops a bit, the current goes up, the regulator gets overloaded, the voltage drops more, current goes up. if there is no automatic current limit, it can get messy. My numbers are rough estimates, but if you don't have over 3 amps available, you may have an issue.

There is also some mention of the center pin on the connector possibly placing the Pro in a lower power charge state.

 

[heed]

The battery is rated at 12.8V 4AH. Will it work?

 

[Wayne Orwig]

Is it a regulated output, or just a battery? If it is a regulated output, you should be in very good shape. If it is just a raw battery, you may have issues as the battery voltage dips and current goes up.

 

[machistmo]

179$ for a battery? Ill just hit a wall outlet more often or use the surface less.

 

[Wayne Orwig]

I found it for about 100. I had to make my own cable.
Where I'll be camping there are no outlets.

 

[riggi]

Where did you find it for $100?

I sometimes have meetings/workshops/classes that go for 3 or 4 hours. If I have 2 back to back, it's not enough time to recharge the surface pro battery.
I have to either bring the charger and hope there is a power outlet I can sit near, or resort to pen and paper and only turn on the SP if I have to refer to a document (and then shut it down again quickly to conserve the power in case I need to look at something else later in the meeting.

A battery pack like this would be good.

How much additional time would this battery give? Would it effectively double the time you could be away from a power outlet?

 

[dc5]

Amazon has consistently listed the "Intocircuit Power Castle Series PC26000" as available for $109.99. However, today it looks like its increased to $119.99. Rakuten (a.k.a. buy.com) had this exact battery pack on sale for $89.99 a few weeks ago. I missed my opportunity to grab one at that great price.

This pack looks suspiciously like the same unit albeit a bit smaller capacity (20000 vs. 26000). Currently at $89.99. http://www.amazon.com/Anker-20000mA...al-Portable/dp/B00B45EOYS/ref=cm_cr_pr_sims_t