Will the V really achieve 8+ hours of battery life? Let's look at the competition

Hi there,

the biggest complain I have about my Surface Pro 4 is battery life. That’s why the V sounds so great, that’s why I reserved mine.

But looking at the numbers…I’m really curious how Eve will manage to get there. With a 48Wh Battery and a reasonable expectancy of 8 hours of battery life we’re looking at 6 W constant battery drain if I don’t miss something. A few questions came to my mind:

  • Does anyone know ho much power the i7-Y will draw in real world use (light web browsing, text editing)? Is there any chance that it’ll be way below the 4.5W TDP?
  • How much power does the igzo panel draw at say 70% (a figure I find my SP4 screen usable under most conditions indoor without beeing to dim)?
  • Will the metal mesh have any effect (positive or negative) on battery life?
  • As most of the tasks people do on their ultraportables involves wifi (or is it just me?): how much does that draw generally draw?
  • The keyboard! As it has it’s own battery: will that not consume the tablets battery at all even if connected physically (given that it is charged)? That would be great news, as a folio keyboard usually draws something between 0.5 to 1.5W alone (depending on illumination i.e.). Or will the tablet battery keep the folio charged at all times?

I hope those questions have not been answered a million times - but I’m really curious.

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4.5W is the very maximum, and judging by higher power laptops, the real consumption can be way below it. My friend’s laptop with a 45W quad core CPU consumes less than 10W during normal use (web browsing, note taking, etc.), and that includes the screen, magnetic hard drive and everything else.
My tablet with a 17W CPU eats more than that, usually around 11W during complete idling. I guess that’s because it’s a 2nd gen Intel Core, quite old :slight_smile:

So, I’d say that it is well possible for our processors to sip only 2-3W of power during light usage.

And wasn’t the estimated battery life actually 12 hours? I was surprised that they estimated 4W consumption for all the components, but I guess it’s possible…

I’ve read that they’re enabling TDP down to 3.5W as well, so that could minimize the drain but i doubt the i7Y will constantly take 4.5W anyways. The tablet will keep the keyboard charged as long as its connected

So, let me give you some rough answers :slight_smile:

The TDP is the maximum the CPU can eat - just as @pauliunas mentioned! :slight_smile:

Now, the Y-Series also has a lower minimum-clock speed compared to the U-Series which also improves the power it draws (lower clocks = less power)

While I don’t have any numbers on the panel, I’d just guesstimate that we have a similar power consumption to the SP4 panel which needs ~5W at 100%, so let’s scale it and we’re at ~3.5W. (According to notebookcheck btw their WiFi test is conducted with ~60% brightness, which is ~150nits, so I believe that would be even lower)

The metal-mesh should not have any effect on the battery to my knowledge.

WiFi does draw a bit of power - don’t have any numbers on it.

The keyboard! While connected to the V (and if it was charged before) it’ll just behave like a Surface Type Cover - so it’ll draw battery from the tablet.

And now, what battery time can you expect?

That depends on your usage! According to notebookcheck in their WiFi test (60% screen, WiFi on, loading a new webpage every 30 seconds) the SP4 i5 goes to 7h with that. Now, multiply that with 1.25 at least (since we’ve got a 25% larger battery than the SP4 i5) and that’s what we should see at least in the WiFi test of NBCheck - which is at least 8.5h. That is without factoring in newer WiFi cards (that should draw less power), Core M over Core i, and other improvements we made to get better runtime :slight_smile:


Wait, so the LCD alone consumes 3.5W of power? Then I really don’t understand how in the world you could estimate 12 hours of usage O.o

Let’s do some simple math:
48Wh / 12 hours = 4W total power consumption
Let’s say we run the LCD at low brightness and get 2W of usage… Then we factor in WiFi with other “minor” things, it should be around 1W. Are you saying that the CPU is able to actually stay running while consuming only 1W of power? That would be insane. I don’t know how you are planning to reach 12 hours… At first I thought it was some super efficient IGZO magic that let it run at 1W, but now…

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While I share your initial surprise at the math, it does appear that, given the consistency of the components between the V and the SP4 and the larger battery, it isn’t that out of question to do this (again, just relative to the Surface).

In those use cases, the CPU would idle between reloads (idling would occur at low frequency (below base clock), potentially <800mhz used for Desktop processor idle) and when not processing encoding (ie only occasionally for “intermittent YouTube use”). Given that use case (again, not max processor, etc) it is not that out of reach for 10-12hrs. From what I remember about your use, you possibly would see more like the 8 hours that the benchmark predicts, and maybe more like 6-7 if the processor and screen get pressed for higher use.

Thanks for clarifying. The 30-second-refresh-test from notebookcheck for the i5 SP4 (the same I have) seems to be quite optimistic, though. I always thought of my use case scenario as a light but pretty common one. Browsing (mostly news websites and Google Docs with battery-friendly Edge), reading and answering mails, adding events to the calendar at 70% brightness and no illumation for the keys gives me 4:54 hours of runtime on average - that’s the number from BatteryBar Pro measured over a couple of weeks. That’s with TurboBoost disabled so the SkyLake i5 U-CPU shouldn’t hit the 15 TDP all to often. And reading around communitys where people try to max out their battery life, I say most people get the same out of their battery. Which is okay by the way knowing about all the technology that battery has to keep alive.

Microsoft claimed 9 hour of battery life for normal use when they released the SP4. Then they changed that a to “9 hours of video playback”. Either way, I somehow feel tricked. Why make such bold claims for a computer that “can replace your laptop” when all you can do to reach that claimed 9 hour battery life is watching videos. Why not say: office work: 4-5 hours, watching videos in a sparely lit room: 7-9 hours.

I’m just writing this in detail because I think Eve should be more conservative about battery life claims or at least not make it such a big selling point. If people start using their V and realize that those “12 hours (real life 10-12 hours use)” are more like “7-8 hours real life use unless you’re constantly watching videos”, they might be disappointed of an otherwise great device.

If the V reaches that 12 or even 9 hours, though, I’m an idiot for not trusting you guys enough. I will then shut up and personally convince more people to buy this device for the battery life alone :wink:

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It would be interesting to know the exact calculation used to come to the conclusion of 12 hours battery life? Is that something maybe @Konstantinos can help us with?


I am agree with @unclickable
According to the battery capacity, processor type and screen size of V, i can estimate only around 9h of real work at 150 cd/m² display brightness. I think, 4W is too low any type of work except idle.
I can imagine how to calculate 4W: 0.5W (SOC) + 3.0W(Display) + 0.5 (Others) = 4W, but i I don’t believe in miracles :slight_smile:

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I’d like to mention, the SP4 display has ~450nits of brightness, and uses 4.8w at maximum brightness. Power usage with these panels is not linear. 50% brightness uses considerably less than 50% power. I’d hazard you’d use 2w at 50% brightness on the SP4. If this panel is more power efficient, then you’re looking at ~1.8w power usage at 50% brightness.

Add in SoC, WiFi, everything else - I could see 4w being nominal usage for the V.

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Agreed, again just to further emphasize, keep in mind that the SP4, in addition to everything else, generally maintained both a higher TDP processor, along with the active cooling solution. Even in the case of the M3 model, the TDP was tuned up to 7W, so it was still a higher power use state (part of the reason for the minimal battery difference between the models). I think that Eve - along with whatever P-State/general CPU tuning that they work out with Intel and the efficiency of the newer generation of processors and chips (though I think the display may be almost the exact same as the SP4, but I could be wrong), should be able to optimize power use quite well here on the V (and still maintain a high performance 2-in-1).

Right at this moment my Toshiba Protégé Z20t-B with m7-CPU gen. 5 draws 5.4W at 25% brightness. At 100% brightness it goes up to 6.5W.

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Well to be fair, there wasn’t a gen 5 m7, only a “Core M for Broadwell”. In any case though, I think points to a fair chance of the chip-set+optimizations making a significant dent in that usage (given the V’s screen choice is higher resolution, but newer tech, it probably somewhat balances to what Toshiba used). At least it is close enough for Eve to get a chance for a crack at it before we get too concerned.

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You’re right - it’s an Intel® Core™ M-5Y71 VPro™ Processor

Just for comparison: the Acer Spin 7 - different machine in many respects but same processor:

  • same i7 7Y75 processor
  • smaller 42Wh battery
  • larger 14" screeen, although just 1080p
  • same fanless design

That’s what the critics say:

The Verge: “a little under 6 hours”
Laptop Mag: 6h 53 minutes
Digital Trends: 8h 35 minutes
PC Mag: 9h 16 minutes

Allthough the numbers differ a lot - everybody seems to complain about the battery life.

I hope the V does a better job thanks to better components and better software optimisation. What’s this algorithm Eve keeps mentioning to boost battery life about anyway?

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And most important of all: On what level does it operate? Is it OS-level or somewhere below, so a change of OS won’t affect the battery performance?

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Man, I love this community for it’s insight.


It’s in the firmware. So when you reinstall Windows, it will still work. But it’s not optimized for other OSs, so it won’t work thatw ell on anything but Windows.

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Any information on what it’ll do exactly?

Sorry, not that I know of.