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Thursday, May 11, 2006

Battery Life Saving Tips for eo

In these few days that I have been playing around with the TabletKiosk eo, I have learned a few things that I want share.

First of all, I want to quote here a comment of Martin Smekal, CEO of TabletKiosk, talking to GottaBeMobile regarding battery life: "The pre-production unit you have does not have it’s power management features implemented, and there are on-going bios modifications that will effect the battery performance in the production unit. However, this being said take into consideration this is a full X86 architecture system running full Windows XP operating system, while utilizing a three (3) cell battery. A standard Tablet PC or Laptop will have at least a six (6) cell battery to achieve 3.5 hours of battery life."

My guess is that they released these units without those BIOS modifications because we still see the same or worse battery life that Rob saw in the preproduction unit. In another hand, I have found that either there is not any Power Management features implemented in these units or they have been very poorly implemented. And the reason why I said that is because during the tests we have found that when switching to some of the Power Management Profiles that are supposed to save Battery the CPU stepping feature goes off and the CPU stays at 1 GHz all the time when it's not supposed to do that. In another hand, the display brightness is preset at a very high level when the unit is running on battery and I have not found a way to set it at 25% and keep it in that way every time that I'm running on battery. From the point of view of Windows Applications, I have not found anything in the eo that can come close to the concept of "Power Management". All I have seen is what you find in Microsoft Operating System.

Add to all these that this unit is not entering into C3 stage (one of the power saving stages that could report up to 15% of more battery life) due to a bug in Microsoft Operating System that has not been properly handled by AMTek/TabletKiosk/VIA in this case. And I said "properly handled" because the problem still there, and it's a known problem by OEMs because Microsoft have been talking about it for a while.

So taking in consideration all the above, and waiting for a solution... here is some tips that will help you to add at least 10 minutes more of battery life to your eo:
  • I know that many of you prefer DIVX format over other formats but... Our tests show that while playing movies in DVIX format the processor worked between 600 MHz to 1 GHz almost all the time. And the CPU load was higher. Playing movies in MPEG-2 format either copying the whole DVD into your HDD or converting the DVD to a smaller MPG is the best way to go because the video chip can decode MPEG-2 and that takes out part of the CPU Load. When using MPEG-2 files the CPU speed stayed most of the time at 400 MHz and the CPU Load was lower.
  • To get more of battery life while playing an MPEG-2 movie you need a software designed to use the VN800 video chip. I tested 3 programs and the best one so far is WinDVD 7.0 (earlier version does not support the VIA chip).
  • After installing Notebook Hardware Control I started to see a better battery life. There are two reasons for that. This program overwrites the Power Saving Profiles in your UMPC and forces a real stepping in the processor if the option for "Dynamic Switching" is selected. The second reason is that this program shows in the System Tray the CPU Speed, CPU Load and Battery Life. Having these meters all the time visible let you know if anything is going wrong and that gives you the chance to correct any settings before is too late.
  • When you unplug the unit from power the display brightness is automatically reduced but not enough. The best results without compromising too much the visibility were obtained when the display brightness was set around 25%.

Just by following these 4 tips I was able to add around 10 to 15 mins more to my initial 1:25 hours. I know that 1:35 is not what you were expecting but.... Hey... Something is better than nothing.

It's a clear fact for us right now that this unit is suffering from a well known and documented bug in the OS that makes the battery to drain faster. That bug can only be fixed by updating the BIOS and doing some changes in the USB drivers. That means that we will have to wait for TabletKiosk final fix. Meanwhile following these 4 tips will help you a little bit.

One more last thing: We contacted early this week TabletKiosk showing them our support giving them all the information that we had at that moment and letting them know about this link where all the test results have been posted. They confirmed to me that they got all this info and that it was forwarded to their engineers. I have not been contacted since then so I assume that they still working in this case but so far they do not have anything to add to what we have found.