SP4 battery life much better with Win 8.1 dual boot!!

[surface15]

Cliff notes version of long article below:
SP4 CoreM:
Out of box, Win10: 6hrs
Highly tweaked Win10: 8hrs
Win8.1 10hrs 30min

------------------------------------------------------------------------------------------

I've been using a SP4 Core-M for the past 10 days.

INITIAL BATTERY LIFE: 6hrs @ 15% brightness

Disabled Cortana by renaming the folder, disabling indexing, disabling MS Edge, using only Firefox with Adblockplus/Noscript/Ghostery, disabling all Telemetry and reporting, setting the screen to 15% max brightness, disabling Bluetooth, screensaver to solid black, disable Aero features (set to optimize speed mode), disable connected standby, disable all Microsoft store apps, disabled MS Defender/security center, disable online accounts, onedrive, and use only local acct. Heck, before I even let the machine have a wifi connection, I even go as far changing the outbound firewall to DENY ALL and disable all Microsoft's pre-allowed filters. This way if an app needs outbound Intenret, I have to set it up beforehand manually.
NEW BATTERY LIFE 8hrs @ 15% brightness

SP3/i5/Win8.1 comparison:
Yesterday I turned on my 8 month old, heavily used SP3. I didn't have to make any of the above OS tweaks. Just used Firefox/Adblock/Noscript on MUCH higher brightness (25-50%) Battery life: LOW: 8hrs 52min, HIGH: 11hrs 32 min, AVERAGE since OS Install: 9hrs 24min. My SP3 Battery charges to 41,192mah, my SP4 charges to 40,324mah.

I had hoped, all along, that the SP4 Core M's efficiency gains (Skylake, low TDP, Passive cooling) would still be more than enough to offset the hungrier demands of the larger screen with more pixels, and the small battery shrinkage in the SP4 (in my case, only 2% difference in mAh). I read many complaints about much lower battery life after people on the forums have upgraded their SP3 from Win 8 to Win10, but I had been assuming that all my countermeaures above would overcome that. I. Was. Wrong.


SP4: Meet Win 8.1 (Dual-Boot option)
Attempt 1: Fresh Install (ISO) Disabled protected mode in UEFI, shrink the SP4 C: drive by 60GB, and insall Win 8.1 from a bootable USB. This DID complete, but there many missing drivers. I could not get online with no wireless driver. I was able to get most unknown drivers installed by copying the Win10 partition's \system32\drivers folder to my Win8 partition, rebooting in advanced startup mode to bypass the forced Windows driver+OS version signature enforcement. However, the wrieless driver still showed (!) error.

Attempt 2: Image file backup & Restore. I used Storagecraft Shadowprotect on my SP3 to image my C: drive. I then booted my SP4 to the Win10 boot option, and used the restore wizard to overwrite my Win8.1 fresh install partition. SUCCESS. Booted up fine, network card driver worked immediately. Windows update pulled down the Intel HD 815 graphics driver (until this was done installing, the brightness could not be adjusted). Everythign seemed fine, but I went back to take care of the 'unkonown device' errors by pointing to the SP3 system32 folder which got most everything. Then I downloaded the SP4 .ZIP file from Microsoft support which got the rest. SUCCESS.

NEW BATTERY LIFE: 10hrs 30min @ 15% brightness

 

[hughlle]

Do you find 15% brightness to actually be usable?

 

[GreyFox7]

I got 11-12 hours Web Browsing with a core m SP4 @ 28% brightness and didn't do anything that crazy^. Running IE (Surfaceformums, reddit, zdnet, cnet, arstechnica, anandtech, realcleartechnology, Wired, others ...) & "Pulse News" aggregator (configured to pull from dozens of sites). I tried this with two Core m SP4s with nearly identical results.

I was going to start turning on other features to measure the impact but I probably wont have time for that.

Turned off Cortana, did not turn off indexing, turned off most Live tiles, notifications, and background Apps. Unchecked keep wifi alive on battery, set brightness to 33% normal/28% dimmed. Turned on Battery Saver all the time which forces dimmed mode, turned off Sync PC Settings, not doing any syncing to Ondrive by default.
IE is configured with Flash disabled & 3 tracking protection lists (aka ad blocking): Easy List, Easy Privacy, Stop Google Tracking.

I'm not saying that Win 8.1 is not more battery friendly than Win 10, clearly it is.

 

[jnjroach]

I go 12-14 hours with my SP4 i5/8/256 running Windows 10 with adaptive brightness, using email, OneNote and assorted other office applications, this is allowing it to enter S0iX between meetings (10-20 minutes between usually).

 

[bugelrex]

Do you happen to have a surface power cover? it works on SP3 but not on SP4.

Since you have the Sp3 image on the 4, would be interesting to see if its hardware blocked or software blocked.

 

[kontrol1]

Cliff notes version of long article below:
Win8.1 10hrs 30min
NEW BATTERY LIFE: 10hrs 30min @ 15% brightness

This is great news. Thanks for posting this.
So you have separate a 8.1 pro license that was used in this case? If I can run 8.1 I may consider upgrading to SP4 one of these days. I am one of those folks who don't really like the Win 10 experience overall and especially the tablet side of it.

 

[surface15]

bugelrex-- I do have a Surface Power cover. No mouse/keyboard input at all with it plugged in, and no new hardware found prompt in the Win8.1 image that I restored to the SP4.

kontrol1--I have unused Win8.1 enterprise licenses from my corporate license. However, Microsoft typically offers free Downgrade Rights for Windows Pro customers. Search for the specifics, but basically you need to provide your OWN media/iso and you are allowed to re-use and re-activate your own product key from another product. Since Windows activation may fail if you have it on more than 1 machine, you have to call to get the activation done via phone. We have done that for clients who have the same key in use on 2, 20, even 200 machines. Perefctly legitimate business use case, but it drives the phone activation people crazy.

 

[ptrkhh]

Are there any issues with 8.1 on the SP4? Apart from Windows Hello, what other features are missing?

Are the cameras, buttons, sensors working?

 

[Zkyevolved]

Wow, that's really cool how you got it to work ... I am personally loving W10,

I go 12-14 hours with my SP4 i5/8/256 running Windows 10 with adaptive brightness, using email, OneNote and assorted other office applications, this is allowing it to enter S0iX between meetings (10-20 minutes between usually).

I've had SO many SP4s (between the i5/128, and then changing to the i5/256, getting one with a wobbly fan, another with defective MD port, etc). I have one now that has a TINY spec of dust under the screen, I don't think it'll bother me in a week if everything else works perfectly... I'll keep my fingers crossed! Regardless, what I wanted to say is that over 6 surface pro 4s I could NEVER get over 9.5 hours of actual usage, even while limiting the CPU to 50%. But I think anything over 6-7 is very acceptable for a device of this form factor and weight. Mind explaining how you're getting 12-14 hours?

 

[jnjroach]

Wow, that's really cool how you got it to work ... I am personally loving W10,


I've had SO many SP4s (between the i5/128, and then changing to the i5/256, getting one with a wobbly fan, another with defective MD port, etc). I have one now that has a TINY spec of dust under the screen, I don't think it'll bother me in a week if everything else works perfectly... I'll keep my fingers crossed! Regardless, what I wanted to say is that over 6 surface pro 4s I could NEVER get over 9.5 hours of actual usage, even while limiting the CPU to 50%. But I think anything over 6-7 is very acceptable for a device of this form factor and weight. Mind explaining how you're getting 12-14 hours?

By not forcing to stay awake, I let go into S0iX with a minute which works perfectly in meetings, I only have Office 2016 x64 for a Win32 Application and use WinRT based Apps for everything else...

 

[KaramjaRum]

I was able to get most unknown drivers installed by copying the Win10 partition's \system32\drivers folder to my Win8 partition, rebooting in advanced startup mode to bypass the forced Windows driver+OS version signature enforcement. However, the wrieless driver still showed (!) error.

I have done what you've done here, however I managed to get the Wireless to connect by installing various SP3 drivers from Microsoft. I can't install any SP4 drivers as they won't install (made for W10), but I'm intrigued by your method above.

Did you simply replace your [W8.1] C:\Windows\system32\drivers folder with your [W10] drivers folder? I attempted this however despite advanced bootup, 8.1 would not boot, always using Automatic Restore mid-boot.

Would love to know how you got those drivers to install, as I don't have a SP3 to image.
Thanks!

 

[ptrkhh]

This is great news. Thanks for posting this.
So you have separate a 8.1 pro license that was used in this case? If I can run 8.1 I may consider upgrading to SP4 one of these days. I am one of those folks who don't really like the Win 10 experience overall and especially the tablet side of it.

Surprisingly, 8.1 does activate with the embedded Windows 10 product key of the SP4.

I have done what you've done here, however I managed to get the Wireless to connect by installing various SP3 drivers from Microsoft. I can't install any SP4 drivers as they won't install (made for W10), but I'm intrigued by your method above.

Did you simply replace your [W8.1] C:\Windows\system32\drivers folder with your [W10] drivers folder? I attempted this however despite advanced bootup, 8.1 would not boot, always using Automatic Restore mid-boot.

Would love to know how you got those drivers to install, as I don't have a SP3 to image.
Thanks!

You can search for "advanced startup eightforums" in Google. Eightforums have quite a lot of nice tutorials about Windows. I cannot link it here because of the forum rules.

Basically drivers that are signed for W10 are not recognized by W8 as signed drivers, and W8 by default only accepts signed drivers. You need to turn that requirement via advanced startup. F7 is your magic key.

Then you can just go to the Device Manager, Update Device Driver, and point it to SP4 drivers pool.

Btw, I just released a W8.1 custom ROM for the SP4 with all the necessary drivers, you can Google it "sp4 custom rom windows 8.1". Once again, I can't link it here due to forum rules.