Thunderbolt draining power?!

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Level 1

14 points

Thunderbolt draining power?!

Hello all -

This is both and FYI and to see if anybody else has come across this:

In Windows 7 64bit Ultimate (via Bootcamp of course) .... On my 15" MBP-RD, when I plug in a Thunderbolt peripheral, it seems to be draining the power from the battery ... even though I have the magsafe plug, plugged into the computer (with the green light on too). When I mouse over the power indicator icon on the bottom right and it states that it's at 97% and not charging. Hasn't gone below 97% so far and that's with about 6 hours of continuous use.

When I unplug the Thunderbolt peripheral, it states it's at 97% and charging, the magsafe plug turns orange and then a few minutes later, the indicator shows Fully Charged 100%.

On the Mac OS X side, it's fine; it stays at 100% (like it should with the magsafe plugged in) ... even with (2) Thunderbolt peripherals plugged in and utilzed concurrently.

Please feel free to chime in if you have run across this issue ... and maybe have a resolution that I've yet to figure out.

Thanks!!

MacBook Pro with Retina display, OS X Mountain Lion (10.8.2), 2.7ghz, 16gb RAM, 500gb SSD

Posted on Dec 17, 2012 1:42 AM

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Answer 1

Csound1

Level 9

59,973 points

Dec 17, 2012 6:51 AM in response to Shaluda

Normal behaviour, you can ignore it.

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Answer 2

Shaluda Author

Level 1

14 points

Dec 29, 2012 11:37 PM in response to Csound1

Normal behaviour?! Hmmm ..... I guess in the Mac universe that would seem most appropriate!!

Turns out though, it's not the Thunderbolt devices that are causing this "normal behaviour". As I've unplugged all T-Bolt devices for a few days now, and the power percentage still fluctuates; even more so as it went down to 91% and then went back up to 100% ... then back down to 98%.

Not a big deal, but still ....

Anyways, I know it's Windows on a Mac ... shouldn't expect everything to be perfect ... but for the amount of money I shelled out for this laptop, I'd expect it to be.

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Answer 3

Csound1

Level 9

59,973 points

Dec 30, 2012 11:23 AM in response to Shaluda

Shaluda wrote:

Normal behaviour?! Hmmm ..... I guess in the Mac universe that would seem most appropriate!!

Turns out though, it's not the Thunderbolt devices that are causing this "normal behaviour". As I've unplugged all T-Bolt devices for a few days now, and the power percentage still fluctuates; even more so as it went down to 91% and then went back up to 100% ... then back down to 98%.

Not a big deal, but still ....

Anyways, I know it's Windows on a Mac ... shouldn't expect everything to be perfect ... but for the amount of money I shelled out for this laptop, I'd expect it to be.

Normal behaviour is to charge to 100% and then allow the battery to discharge to 95% approx, then recharge to 100% and decay again. It avoids overcharging the battery.

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Answer 4

Shaluda Author

Level 1

14 points

Dec 31, 2012 1:45 AM in response to Csound1

OK ... so why is it when I'm in the Mac OS, it ALWAYS shows 100%?

Also, I've got a $400 HP laptop and it never did / does this.

Please don't take this as a deragotory or rant; it's just that I'm quite curious about this.

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Answer 5

Dragorth

Level 1

0 points

Dec 31, 2012 6:08 AM in response to Shaluda

What type of MacBook is it? On certain models, like my Macbook Pro early 2011 with AMD graphics, Apple has disabled the built in Intel graphics while in Windows, so my laptop's dedicated GPU is always running. In OSX, the Intel graphics are used until a program needs the power of the dedicated AMD GPU. This is why I can turn every thing off in OSX, and turn down the monitor to get close to 10hrs of battery life, and I struggle to get 6 in windows under the same constraints.

Hope this helps.

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Answer 6

Csound1

Level 9

59,973 points

Dec 31, 2012 10:24 AM in response to Shaluda

Shaluda wrote:

OK ... so why is it when I'm in the Mac OS, it ALWAYS shows 100%?

Well, I don't believe that you watch it "ALWAYS"

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Answer 7

Shaluda Author

Level 1

14 points

Jan 2, 2013 10:46 PM in response to Dragorth

Thanks for your reply Dragorth.

I'm not sure if you understood my original post. It's not a matter of how much battery life is available when the laptop is unplugged, I referring to when it's plugged in that I see the percentage drop .. on the Windows side only. The Mac side is fine; always at 100%.

My laptop is the 15" MBP-RD with an nVidia GPU. I checked (or unchecked; forget which way it is) the box to disable automatic graphic switching in the Mac OS. So it's always utilizng the nVidia GPU, not the Intel HD4000 GPU.

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Answer 8

Shaluda Author

Level 1

14 points

Jan 2, 2013 10:48 PM in response to Csound1

Thanks for your reply Csound1.

Believe what you like.

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Answer 9

Dragorth

Level 1

0 points

Jan 2, 2013 10:54 PM in response to Shaluda

I was speaking about it plugged in, and used the example of how long the battery lasted only to demonstrate how mach of a difference using the gpu versus the intel graphics makes.

As for turning off switching, that only affects Mac OSX. The Nvidia drivers in Windows would need to be changed to have similar settings. It may be that the Gpu is using more power in one OS compared to the other. (The drivers work differently, due to both the differences in the OS, and the fact that Windows is targeting DirectX 11 performanc, while Mac OSX targets OpenGL 3.2. DirectX 11 is roughly equivelent to OpenGL 4.x, so depending on the programs used, it is quite possible for this to happen.

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Answer 10

Shaluda Author

Level 1

14 points

Jan 3, 2013 12:49 AM in response to Dragorth

Dragorth wrote:

I was speaking about it plugged in, and used the example of how long the battery lasted only to demonstrate how mach of a difference using the gpu versus the intel graphics makes.

I understand; good example.

Dragorth wrote:

.....

As for turning off switching, that only affects Mac OSX. The Nvidia drivers in Windows would need to be changed to have similar settings. It may be that the Gpu is using more power in one OS compared to the other. (The drivers work differently, due to both the differences in the OS, and the fact that Windows is targeting DirectX 11 performanc, while Mac OSX targets OpenGL 3.2. DirectX 11 is roughly equivelent to OpenGL 4.x, so depending on the programs used, it is quite possible for this to happen.

I understand this as well, but what doesn't makes sense, is that it does this power percentage fluctuation even when I'm not running any programs ... unless you count the screen saver.

Seems like (don't know for sure about this) that the nVidia GPU is always "ON" in Windows?!

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Answer 11

Jan 3, 2013 3:58 PM in response to Shaluda

If you have a system with a sufficiently fast enough processor, it is possible to drain your battery while the system is conencted to external power. I have a Late 2011 MacBook Pro quad Core i7 processor. If I am running a large video rendering process, I can start with 100% battery, and by the tim eit finishes 2-3 hours later, I am down to 25% battery remaining, even though it has been connected to external power all the time. When the processor is running at full capacity, plus the GPU running at high capacity, the system will draw more than 85W, but the power adapter only provides 85W to the system, so in order to meet the needs, it will draw from the battery to suppliment the power adapter. While I don't care for this, I understand it has to do with the power adapter not providing enought power to meet the needs when the system is running at full capacity.

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Answer 12

Shaluda Author

Level 1

14 points

Jan 3, 2013 8:32 PM in response to GeekBoy.from.Illinois

Thank you for your reply GeekBoy.

GeekBoy.from.Illinois wrote:

If you have a system with a sufficiently fast enough processor, it is possible to drain your battery while the system is conencted to external power.

I have had more than a few Windows only based laptops and have never run across this issue. Add to that, I was utilizing the CPU and GPU quite intensively (video editing, effects rendering and yes, even some gaming too!!). But I'm not stating that it's not possible or that I don't believe you, ... I'm just stating that I've never seen the power fluctuate like it is on my current MBP .... especially while it's not running any intensive CPU / GPU applications.

GeekBoy.from.Illinois wrote:

When the processor is running at full capacity, plus the GPU running at high capacity, the system will draw more than 85W, but the power adapter only provides 85W to the system, so in order to meet the needs, it will draw from the battery to suppliment the power adapter. While I don't care for this, I understand it has to do with the power adapter not providing enought power to meet the needs when the system is running at full capacity.

That makes total sense and I agree with you on this because ... the battery (at least in my MBP) is rated at 95watts and the MagSafe Power Adapter is rated at 85watts. Seems to me like it should be the other way around?!

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