Kohjinsha SC3 – Battery life breakdown and tips.

Updated on 11 November 2019 by

As you might have read, I have been very disappointed with the battery life figures on the Kohjinsha SC3. I was expecting a lot lot more from an Ultra Mobile PC built on Intel’s latest battery-optimised Menlow platform but it turns out that under normal use, this device is just as bad as many devices based on the previous platform. Over the last 24 hours I’ve spent a lot of time trying to analyse why and have finally come up with the reason. Invetec, the OED for this device, have cut corners. While the background drain (on the motherboard and power board) is better than on previous Kohjinsha’s, it’s no better than the HTC Shift, Q1 Ultra. All these devices can match the SC3 for background efficiency. About 4W minimum or 5-hours, is what you can expect with everything turned off but the processor.

OK, 4W is good but once the screen is on, boom! Up goes the battery drain by between 80 and 150%. This is exceptionally high drain for what appears to be a LED-backlit screen. Thank goodness that using the screen in a bright room requires only 3/8th brightness but it’s still about 3W of drain which is much higher than it should be.

The second shock comes when you turn the VIA, yes VIA!,  USB Wifi module on. Connecting to a hotspot will push the drain up by over 3W. It will settle back to 2W after connection but this is, quite frankly, pathetic. A wifi module that takes more power than the processor is a joke. There are far more efficient Wifi modules out there. Did Inventec think they were designing a cheap netbook?

So from a background drain of 5W, if you want to surf the net in a bright room over Wifi, the battery life drops to a depressing 2hrs. This is an average drain of 10W which is no better than the devices mentioned above.

Breakdown, tips and summary follow…


Here is the breakdown using Windows Vista Ultimate. 1GB RAM. Optimisations done. SP1 installed. ‘Balanced’ battery mode.

  • Background drain: 4-5W
  • Wifi: 1.5-3W
  • Screen: 3-6W
  • Other radios: (BT, GPS): Max 1W
  • CPU: Max 2W.
  • GPU/Chipset: Max 2W.

Apart from the CPU and Chipset, its a horrible set of figures. The Wifi should be around the 0.5W mark and the screen well under 1W. [Here’s some more detail of where I think it should be with Menlow in 2008.]

How to get 3 hours browsing / typing time.

The SC3 has a good range of component control available through on-screen icons, keyboard shortcuts and BIOS settings. The trick, for mobile use, is to set all radios to off and to set ‘silent’ mode on the fan. Ideally, you should set this in BIOS so that the device boots up in this state by default. There’s even a ‘long-term-mobile’ BIOS setting that does this for you. (Obviously Kohjinsha knew how much the extra components affect the battery life!)

Setting all components to OFF and setting the screen to 3/8ths, the SC3 will sit doing nothing and give you well over 3 hours of typing time on a word processor. That’s if you really fancy typing for 3 hours on the tiny keyboard. E-Book reading (which is fairly comfortable on the hi-res, high-brightness screen, will give you 2.5 hours of battery life at the 50% setting. Outdoor use will see that drop to 2hrs as you pump up the backlight.

If you need to go surfing though, the big trick is to use a mobile phone modem over Bluetooth. Bluetooth takes very little power and if you’ve got a 3G contract, you’ll be happily surfing for up to 3hrs. Keep those flash-heavy pages closed after you’ve used them though! Single-tab browsing is the answer. Its a compromise but it works.

Vista and Disk.

I have a suspicion that the disk never spins down under Vista. I’ve been watching the read/write figures under Vista’s performance monitor and it seems that pagefile, logging and software services processes are always accessing the disk. One answer to this could be more memory. It would certainly reduce the need for the pagefile which seems to be the worst offender. Alternatively, moving to a simpler OS might be the trick. I’m tempted to try out XP to see how that affects the figures. Once I’ve taken a disk image, I’ll do it.

Further tests.
  • Removing the TV module. Its possible that this is draining some power on the USB bus.
  • Updating drivers for screen and Wifi. The screen is currently using a generic driver. There may be drivers that support extra power-saving features.
  • Switching to Windows XP. When I did this on the Q1 Ultra, I saw big gains. 10-15% battery life savings. Drivers for GPS and camera could be a problem but for mobile surfing, this could be worth trying.

The Kohjinsha SC3 is no showcase for the Menlow platform. The screen and Wifi take far too much power and negate any gains that might have been had from the Intel silicon. Adding an extended battery is an option but its a compromise that shouldn’t have to be made. Kohjinsha should have built the SC3 with a minimum 3-hour Wifi-on surfing time and users should not be expected to pay extra and compromise on size and weight with an extended battery. In fact, I don’t think pro-mobile users are going to make any compromise at all. They’re just going to walk right past the SC3 and look for a different solution. Unless I unlock significant advantages in further testing, i’m going to be doing exactly the same thing.

30 Comments For This Post

  1. JC says:

    This is why, BTW, I thought it was misleading when you tested the Gigabyte M528 with the screen off, then proclaimed it to be a sub 4W PC. When you have the device right in front of you, measuring how much power the screen consumes is much more accurate than estimating. Sometimes, it’s surprising how much power a screen uses.

  2. chippy says:

    Yes. You are right. Screen off tests can be difficult to extrapolate into the real world. I feel confident about the M528 estimate based on real-world use on the device but we’ll never know for sure until he final production device comes out.

  3. Jenn says:

    Someone who successfully installed XP Tablet on the SC3 said “power/battery consumption seems the same” as it is with Vista (Home Premium, I think). More here: http://forum.pocketables.net/showthread.php?p=7077

    Although the increase in battery life would be nice, I don’t think I would choose Bluetooth tethering if wi-fi was available. 3G is certainly fast, but wi-fi is faster. Actually, I wonder how great the gains in battery life really are when the slightly longer load times are considered.

  4. cah says:

    I have heard the same. I have personally found that once you disable vista background processes and stuff that can use more cpu cycles the difference comes to within 5% or so. Well within margins of error. Even 10% or 20% changes can be experienced if the runs are done under different ambient temps for instance.

    Apparently vista has improved low-power modes (especially useful for standby i guess) and has more advanced cpu throttling, but in absolute terms I have never seen vista best XP for battery life.

    3G is also incredibly expensive compared to Wifi…and if you have an 02 data plant with wifi+3G I believe the ‘fair use’ bandwidth is much higher on wifi too.

  5. chippy says:

    I do get the impression that Vista SP1 is better but so far, its not something i’ve been able to measure.
    Thanks for the feedback on this.

  6. Zapgun says:

    I briefly tried using XP on my SC3, but had trouble with the video drivers (everything else worked perfectly), so I switched back to vista. XP was pretty good – fast and responsive (gave me a few more FPS in the games I tried as well).

    Now that it looks like there are are better video drivers out there, I’ll have a second look at XP. Intel, interestingly enough, is making it hard to get a hold of the XP IEGD drivers. Previously they were stuffed away on their site, and now they’ve been moved to an private area, making them unavailable for us non-developers.

    If anyone knows here I can get the latest IEGD_9_0_GOLD_1198 driver set now, I’ll try XP again and post some results.

    P.S. Chippy, I had troubles with my forum login and sent you a comment about it, any chance you can look into it?

  7. Zapgun says:



  8. chippy says:

    Excelent work.

  9. chippy says:

    Zapgun. Your account is now authorised. I guess you didn’t get the auth email. (Sometimes ends up in spam folders) Try to login with the details you registered with.


  10. Zapgun says:

    All good now thanks Chippy.

  11. martin says:

    Hej, your comment mentioned games… Can you tell us what games have you tried and what was the speed/playability?

  12. Zapgun says:


    As Chippy mentioned, this machine is not going to give you amazing game perforamce – so expected some pretty horrible frame rates.

    That being said, it ran a good selection of games. I’ve noticed however that opengl support seems limited (I’m hoping that will improve with driver releases – GLDirect is an alternative I suppose). Most of the games I tested were at 640×480.

    Games I’ve tried:
    – Fallout 1 I couldn’t get to run at all (I’ll look at why later).
    – Homeworld2 wouldn’t run (its opengl based).
    – World of Warcraft ran at somewhere between 5 and 10 FPS – I couldn’t get opengl to work with it.
    – Warcraft 3 ran ‘decently’ (no clue on frame rates but I’d guess around 10-15 fps).
    – Dawn of War ran in a similar fashion to Warcraft 3.

    As I’ll be going on vacation soon and want to stock up on games for the trip, I’ll try Vampire the Masquerade, UFO, and a few others. I can let you know what I find out when I do.

    Hope that gives you an idea of what to expect,


  13. Zapgun says:

    [Replying to my own thread.. how sad is that.. anyways….]


    I found this forum post [http://origamiproject.com/forums/thread/28058.aspx] talking about playing WoW on the Q1U, which only has a 800MHz CPU and 1GB of 400MHz RAM. According to the post, the guys here are getting a framerate of around “18-26 when grinding in the desert areas in Tanaris , around 15-19 in Darkshore and down below 10 in Gadgetzan or in other town areas.”

    Either this new chipset from Intel is the biggest ripoff they’ve produced, or there’s something seriously wrong with something on the SC3 (be it drivers or hardware).

    I would love to know which.

  14. Klas says:

    The the torrent with the Windows XP drivers should work now:

    Please note that these were generated with the IEGD_9_0_GOLD Eclipse based tool that Intel provides.

  15. Jenn says:

    Re: OpenGL. I’ve been chatting with a fellow who’s in touch with PowerVR (who make the 3D and VXD drivers) and he said that Intel has to incorporate them into the Poulsbo driver. PowerVR have purchased an SC3 to see what they can do, but at the moment there is no OGL support in the hardware and only poor D3D support (I ran D3DVillageMark with less-than-stellar results).

    He also pointed me to a new Poulsbo driver (released 7/24): http://downloadcenter.intel.com/filter_results.aspx?strTypes=all&ProductID=3001&OSFullName=Windows+Vista*+Ultimate%2C+32-bit+version&lang=eng&strOSs=156&submit=Go!

  16. fab says:

    .. no problem. the fact is, we expect too much. lower your expectations and everything will be fine.

    in general i get 30min or more out of GNU/linux over Vista when installed on my notebook(s). so in general microsoft drains more battery than GNU/linux – my experiences.

    the other thing is, just don’t buy those expensive devices if they don’t satisfy the needs. we all appreciate people like you Steve, because you cover up limitations which, honestly, i would never want to pay a premium price for. if a celeron in an asus brings 3 hours and the atom 2 hours but costs 2 grand more…don’t know, am not masochist to pay more to get less

  17. chippy says:

    I ‘cover up’? Or do you mean i that I dont cover up / uncover?!!

  18. fab says:

    oops…sorry… i missed the “don’t”… so it would be “..don’t cover up limitations..”

  19. Mark says:

    Actually, I think that we are all missing something here – this device is designed for Japanese consumers.

    My personal experience when living in Tokyo for 5+ years was that Japanese consumers value small size *more than* things like battery life! Spend a few hours rooting around Akihabara, and you’ll see what I mean.

    I personally find this disappointing and very frustrating, but that said, I do love the size of the SC3! I think that Kohjinsha, knowing that JP consumers value size most, have just been lazy on the battery front.

    Chippy – any chance you could do a short write up of *how* to install XP on the SC3, with links to *all* the necessary drivers [or all *available* drivers], etc??????

    I’ll be getting an SC3 in the near future, so if someone could do such a writeup, it would definitely help me, and I suspect quite a number of others who are not convinced that Vista is the way to go on a UMPC.

    Anyway, looking forward to more SC3 articles…


  20. chippy says:

    I’m sure that the Japanese, being more into Ultra Mobile computing than westerners, appreciate good battery life so I don’t think it excuses Kohjinsha at all. As you said, I think they’ve been either lazy, or, more likely, have cut corners to get to the market quickly.

    As for that XP article. If I ever upgrade, I’ll certainly be writing it up. I’ll probably wait for new Poulsbo/vista drivers first though.


  21. dimsumfan says:

    Chippy, for novices like me, do you have specific instructions on how to do this: “The trick, for mobile use, is to set all radios to off and to set ’silent’ mode on the fan. Ideally, you should set this in BIOS so that the device boots up in this state by default. There’s even a ‘long-term-mobile’ BIOS setting that does this for you.”

  22. chippy says:

    The easiest way is to switch the switch on the front ro ‘RF OFF’. If you want to make sure that GPS, etc is off too, you can use the on-screen icons.
    As the for the BIOS method, its an easy ‘switch’ in the setup screen. I can show you if you need help at some point in the future.

  23. SeniorDad says:

    Thanks for confirming my suspicions that the Wifi adapter had something to do with the battery performance of this thing. I started noticing that about 30 minutes into my 1 1/2 hour-max untethered browsing session my connection speed would plummet.

    Since I had the power saving setting set to Power Saver, the machine was kicking the voltage to the adapter down a notch or two. Aside from that, at least for me, the Wifi adapter is just a poor performer. I’m getting far better performance tethered to my cellphone.

    Who’s first to rip this thing open?

  24. martin says:

    It would be interesting to try one of those EXTERNAL usb wifi sticks. They claim power consumption around 400mA max.

  25. shinryu says:

    How difficult is it to upgrade the wifi card in the SC3? I know not many people would be willing to do this sort of upgrade, but I’m really curious how salvageable the SC3 is. I doubt there’s a way to really fix the screen, but it might be possible to help wifi a lot if the card was swapped, right?

  26. SeniorDad says:

    I just did.

    And I’m sad to report that, for me at least, it made no difference in my rapidly dwindling (yes, I said dwindling) battery life.

    Not ready to call this thing a mistake yet, but I’m getting there.

    At least it’s kept my “System Restore” tab busy.

  27. zapgun says:

    There has got to be something fundamentally “not working as expected” here as too many things seem to be going wrong with this unit. I’m in power save mode and I can hear my hard drive clicking away every 20 seconds, the graphics are performing badly, its eating power where it shouldn’t, etc. Maybe these Intel beta drivers are just really bad. :/

  28. heavyharmonies says:

    I noticed this as well under Vista. Even with nothing running, the hard drive would loudly fire every 10-15 seconds, regularly.

  29. chippy says:

    Mmm. I need to open it anyway.
    I’ll have a go now….


  30. chippy says:

    It doesn’t open easily so i’m not going in hard at this stage. I think i’ll keep the device in the best condition possible just in case I need to sell it.
    (Offers accepted in Europe!)


2 Trackbacks For This Post

  1. Wibrain L1 Atom/HSDPA/SSD UMPC details. | UMPCPortal - The Ultra Mobile Computing reference site says:

    […] this figure with the standard battery and a low-level backlight but it’s going to be tough. We know that already! Availability is planned for October through global channels. (Yes, U.S. is included in the target […]

  2. Samsung got it right. (With last years tech!) | UMPCPortal - The Ultra Mobile Computing reference site says:

    […] week I posted some tips on how to squeeze 3 hrs browsing time out of the Kohjinsha SC3. The method was a bit of a trick as it utilised a mobile phone data connection over Bluetooth but […]

Recommended Reading

Top Ultra Mobile PCs

Dell Latitude E7440
14.0" Intel Core i5-4200U
GPD Pocket 2
7.0" Intel Core m3-8100Y
Viliv S5
4.8" Intel Atom (Silverthorne)
GPD Win 2
6.0" Intel m3 7Y30
Lenovo Ideapad Flex 10
10.1" Intel Celeron N2806
Acer Aspire E11 ES1
11.6" Intel Celeron N2840
HP Elitebook 820 G2
12.5" Intel Core i5 5300U
Microsoft Surface Go
10.0" Intel Pentium 4415Y
Acer Aspire Switch 10
10.1" Intel Atom Z3745
LG G8X THINQ Dual Screen
6.4" Qualcomm Snapdragon 855