HP Elite X2 1012 Discussion Thread

Discussion in 'Hewlett Packard' started by SF6, Dec 27, 2015.

  1. RT545

    RT545 Scribbler - Standard Member

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    I do agree that, beside this problem, this is a very good device, and I said it several times, especially about the upgradable aspect that is rare on a tablet.

    This is precisely why this is so frustrating:

    This is not the battery drain that bothers me. If it drains at a normal rate DURING USE, then this is normal use case that is acceptable.

    What bothers me is that it actually DOES SOMETHING WHEN IT IS SUPPOSED TO BE OFF. There is a program running in the background, doing things, executing code, while the device is shut down. And you may suspect that this may eventually be used to reactivate the machine while off, if an attacker can design a way to do so.

    As a developer, I prefer to have complete control on my machine, and be able to know what it does, and this includes the ability to completely shut it down. But I understand that others can actually live with this.
     
    Last edited: Sep 11, 2017
  2. mikewho

    mikewho Pen Pal - Newbie

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    To qualify my experience - this is still based on battery drainage from a potentially faulty/expired battery. I will be conducting the same tests once I receive my unit back after having been repaired (I shipped it off yesterday afternoon).

    The issue with battery drain while shut off is that a lot of people have the use case of sporadically using the computer for times when working remotely/mobile versus while in the office. This could mean a week/weeks at a time between uses, and if working while mobile this also means potentially not having immediate access to A/C power. I want to be able to reliably go a week without using it and know that when I turn it on, it will have (at least close to) the same amount of power in it as when I last shut it off so that I can use it for the 30-60 minutes I need to and not have to plug it in.
     
  3. RT545

    RT545 Scribbler - Standard Member

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    One may also have a use case where several machines are used by one individual, and so one machine may remain off for some time...


    You can get an idea of what the normal battery drain should be when a device is fully off and has no activity there:

    http://batteryuniversity.com/learn/article/elevating_self_discharge

    A litthium/ion battery has the following self discharge characteristics:

    5% in the first 24h, then 1–2% per month (plus 3% per month for safety circuit)

    Which sums-up to about 5% per month (and not 5% in 24 hours, which is the rate for a device with a slight activity!)

    This is what I generally observe in my computers while truly switched off.
     
  4. RT545

    RT545 Scribbler - Standard Member

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    Not really; I just think that we pointed out a problem (a device that is never truly off because keeping some form of activity while off) and another problem (HP not correcting this bug despite several users fighting with support to report it and more than 15 BIOS releases) and that we are still discussing about the issue today.

    Given the price you pay for the device, wouldn’t you be pleased if you knew bugs were corrected?
    (I personnaly waited for the bug to be corrected before I could buy the device again, which unfortunately never happened).
     
  5. mikewho

    mikewho Pen Pal - Newbie

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    The article you linked to quotes a 20% discharge after a month (when at 25° Celsius, i.e. SATP) when starting at full charge (based on Table 4 in that link). This is still a lot lower than the 6-7% per day we have had reported with this device. It's also noted that once the battery discharge rate drops to 4% per month by the time it's at 40-60% charge (based on Table 4 again). So worst-case you're at maybe 65% total charge after 60 days (less than 5% per week on average).

    For additional information, the HP tech that assisted me with my case had offered an explanation for the need to maintain a level of battery drain with the device - specifically, he said the computer needs to keep the system date and time progression. This I can understand, though that type of operation seems to be no problem for a standard wristwatch using a 3V watch battery that lasts 6-12 months (while also displaying the date/time, but we'll put that aside).
     
  6. RT545

    RT545 Scribbler - Standard Member

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    Let’s do a bit of calculation here (please correct me if I made a mistake!)


    The battery has a 47 Wh capability, so it contains 47*3600 = 169200 joules of energy when fully charged. 6% of that means that is looses 10152 joules of energy in 24 hours. This makes 423 joules per hour, and so 0.1175 joules per seconds. So the drain consumes around 0.1 W of power.

    As an example, we can consider a led like this one:

    http://uk.farnell.com/multicomp/703-0100/led-5mm-red-400mcd-643nm/dp/2112111

    it consumes 20 mA at 1.8 V, and so 36 mW of power (0.036 W), so the drain is sufficient to fully lit three of those diodes during 24 hours.

    (That’s why you hear a lot of crackling when approaching an ordinary radio: electrostatic charges still moving in the device while switched off, and a drain circa 0.1 W)

    The CMOS clock in computers is typically maintained by a CMOS battery, of type CR2032, which has 210 mAh/3V capability, so 630 mWh, so 0.63*3600 joules = 2268 joules of energy contained. CMOS clock are typically emptied in 5 years (157788000 seconds!) which gives a much lower power consumption of around 1.44*10^-5 W to maintain the CMOS clock, so several orders of magnitude lower than the power to lit three leds.
     
    Last edited: Sep 13, 2017 at 5:26 PM
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