1. peter9477's Avatar
    Some past thread which I can't find now had some brief discussion about whether the battery drained much while the PlayBook was powered right off (i.e. not just in standby).

    It should be obvious that there's minimal drain, since almost nothing is actively using power. There's at least one small thing that does: the tiny microcontroller which basically all Lithium batteries have integrated into them for, among other reasons, safety (to cut off power if the voltage drops too low, where it would seriously damage the battery).

    On January 28 I turned off my original PlayBook, which has had 169 recharges, and has an OS-calculated health reading of 89% (as reported by Battery Guru).

    At the time, it reported a voltage of 3.93V, and 72% battery level.

    Today I powered it back on and, after a reboot that took 155 seconds (the OS 2.0.0.7111 beta) and reported 2.64W drain at the end of that, it was reporting 70% and 3.87V. (Note that rebooting used up 0.55% of the battery's charge in this case.)

    Within about a minute it was showing 69%.

    Considering that as a 3% drop, so that the estimate is extremely conservative, the math says that it would take 350 days to drop from 100% to 0% this way.

    In reality, the value is probably closer to two years, but for now I'd call this a lower limit.

    I don't recommend anyone try this at home, since it would mean having your PlayBook unavailable for (in this case) almost two weeks! :-)
    02-07-12 12:17 PM
  2. dugggggg's Avatar
    Some past thread which I can't find now had some brief discussion about whether the battery drained much while the PlayBook was powered right off (i.e. not just in standby).

    It should be obvious that there's minimal drain, since almost nothing is actively using power. There's at least one small thing that does: the tiny microcontroller which basically all Lithium batteries have integrated into them for, among other reasons, safety (to cut off power if the voltage drops too low, where it would seriously damage the battery).

    On January 28 I turned off my original PlayBook, which has had 169 recharges, and has an OS-calculated health reading of 89% (as reported by Battery Guru).

    At the time, it reported a voltage of 3.93V, and 72% battery level.

    Today I powered it back on and, after a reboot that took 155 seconds (the OS 2.0.0.7111 beta) and reported 2.64W drain at the end of that, it was reporting 70% and 3.87V. (Note that rebooting used up 0.55% of the battery's charge in this case.)

    Within about a minute it was showing 69%.

    Considering that as a 3% drop, so that the estimate is extremely conservative, the math says that it would take 350 days to drop from 100% to 0% this way.

    In reality, the value is probably closer to two years, but for now I'd call this a lower limit.

    I don't recommend anyone try this at home, since it would mean having your PlayBook unavailable for (in this case) almost two weeks! :-)
    The Lipo self-discharge rate alone (quoted at 5%/month by Wikipedia) would account for half the loss you reported over the ten day period.
    02-07-12 12:29 PM
  3. Chaddface's Avatar
    The Lipo self-discharge rate alone (quoted at 5%/month by Wikipedia) would account for half the loss you reported over the ten day period.
    I thought I read somewhere that the PB's were shipped with a 40% charge. That means most PB's in warehouses would have dead batteries by now?
    Last edited by Chaddface; 02-07-12 at 12:42 PM. Reason: Predictive text.
    02-07-12 12:40 PM
  4. dugggggg's Avatar
    I thought I read somewhere that the PB's were shipped with a 40% charge. That means most PB's in warehouses would have dead batteries by now?
    I don't know about the 40% figure. I got mine in late November, 7.5 months after it was supposedly manufactured in early April. Plenty of charge left to do both the EULA and initial OS download/upgrade.

    However, if true, it might explain the timing of the great Black Friday fire sale...
    02-07-12 01:44 PM
  5. dugggggg's Avatar
    > Last edited by Chaddface; Today at 01:42 PM. Reason: Predictive text.

    Let me guess---it typed "whorehouses" when you meant "warehouses"
    Chaddface likes this.
    02-07-12 01:48 PM
  6. peter9477's Avatar
    Chaddface, not necessarily. As I've noted in other posts, that so-called "build date" that people see on the printed labels on the box is almost certainly not the actual date of production, and I don't believe the 1.5M (or 1.8M or whatever) PlayBooks were fully built and assembled and boxed at the same time way back before April.

    More likely they built and ordered the parts for about that many, except for the batteries, which do have a shelf-life. Many were assembled fully and packaged, while many more were assembled almost fully but had the batteries left out. As they needed them, they probably finished batches of them by installing fresh batteries, which were charged to around 40%.

    If someone who got a "recent" one wants to pop open their PlayBook (not recommended!) they would quite possibly find a date code on the battery which would support this theory a bit.

    That said, there probably are some few left from the early days, which were buried in the back of some crappy store that made no effort to sell any, and if you get one like it may have drained quite far down...

    By the way, as for "self-discharge"... I have no idea, but some things I've read claim that Lithium batteries basically do not self-discharge, but that they drop over time solely because of the aforementioned microcontroller which monitors them. If that's true, it wouldn't likely be a fixed percent per month either, but rather a fixed average current consumption. In other words, much lower percentage on larger batteries. I don't know what the wikipedia article had for its source on that.
    Chaddface likes this.
    02-07-12 01:50 PM
  7. kennyliu's Avatar
    I also noticed that, if my playbook stays off over night, upon startup it loses a few percentage points within a few minutes. But it's good to know that I can leave my PB turned off for many many days. Not that I intend to do so
    02-07-12 02:04 PM
  8. peter9477's Avatar
    I'd always read 40% was typical, but I'm sure there's little difference. It would also make sense that, since 0% is not a standardized concept for Lithium batteries, there would be some variation in that value. (Both are in the same range of voltages, since there's a nice plateau in that area. See the bottom group of data in this plot: imgur: the simple image sharer )

    I think most PBs may ship with around 40% however... I've heard of none ever having more than 40% (but with a sample size of only maybe 30 to draw on so far).
    02-07-12 02:05 PM
  9. ScoobsDM's Avatar
    Lithium batteries do have a self discharge rate as all batteries do. However their discharge rate is roughly 3%-5% of a normal battery. So their shelf life is 95% better then an alkaline battery. Most battery manufactures do charge the batteries to a specific percentage based on the purchasers need. My company buy 8' 29.5volt Lithium batteries fully charged because we need them at 100% when they leave the shop area, and we do not have a proper charging station for these batteries.

    So by this if an alkaline battery drops 10% per month (easy number to work with) a lithium battery will drop 3%-5% of that. Now the determination of the actual voltage drop would depend on the max charge of the battery at the time of storage. Lithium batteries do not drop the same "voltage" per month, the actually "voltage" drop decreases as the total charge of battery decreases.

    Now once installed in a device the circuits that keep time/date/rom/etc are constantly pulling on the battery even in "OFF" mode. So the decrease in the battery would depend on the idle circuit it's connected to. ICs/zeners/crystals/etc.
    02-07-12 02:24 PM
  10. TinRobot's Avatar
    "Powered off"? The PB can do that????
    bbvj likes this.
    02-07-12 02:33 PM
  11. peter9477's Avatar
    Lithium batteries do have a self discharge rate as all batteries do.
    Ah, I found what I'd earlier read, and partly misremembered above. In the wikipedia page on Lithium-ion batteries (not even Lithium-Polymer, which are not by any means identical):

    "According to one manufacturer, lithium-ion cells (and, accordingly, "dumb" lithium-ion batteries) do not have any self-discharge in the usual meaning of this word.[33] What looks like a self-discharge in these batteries is a permanent loss of capacity (see Disadvantages). On the other hand, "smart" lithium-ion batteries do self-discharge, due to the drain of the built-in voltage monitoring circuit."


    Not sure it means anything much to us here... might just be a question of semantics. After all, you basically can't use Lithium (safely) without having the voltage monitoring circuit in place, so it's a bit pointless to worry about the source of the self-discharge...
    dugggggg likes this.
    02-07-12 02:37 PM
  12. FF22's Avatar
    I am guessing the CLOCK/Calendar is also running when off?

    I will say that IN STANDBY my new 64gig loses very little overnight.

    I will check the speadsheet but I decided to try another experiment with the 32gig. I changed its STATIC ip address to the "auto." Thinking maybe that aspect changed its interaction with the router. I don't think so from just looking at Battery Guru's graph. The 32 seems to have lousy standby power loss. There are also a few more apps on it than on the 64 so maybe one of the other gps apps is acting up even if I don't run it???

    When I went to the Sierra for two weeks in July I powered the 32 off and unplugged it. When I returned it showed almost not loss.

    Speaking of standby (in a POWER OFF THREAD): Peter did you mention that Rim has not reacted kindly to standby power losses as far as rma?
    02-07-12 03:17 PM
  13. peter9477's Avatar
    I am guessing the CLOCK/Calendar is also running when off?
    Sort of. We have no evidence yet that (like the phones) the PlayBook can actually will power on automatically based on a clock. It's possible it's there but just not supported in software yet.

    Whether it's there or not, at the very least there's something like a 32kHz "watch crystal" powering a tiny clock chip of some kind, or a portion of the main chip that continues to run just enough to increment a counter based on this crystal's oscillations. (It would use probably in the nano-ampere range, so extremely little power. Those crystals are used because they're very accurate and very low power.)

    This isn't really any different than how a PC handles this, with some clock circuitry in the "CMOS" to handle the calendar function when it's off.

    Speaking of standby (in a POWER OFF THREAD): Peter did you mention that Rim has not reacted kindly to standby power losses as far as rma?
    I've not heard of anyone who actually attempted to complain to them or inquire about standby power consumption. I've only speculated that they may claim there's no specification for it, and therefore no cause for warranty support for anyone claiming a problem in that area, unless it's exceptionally high (e.g. 1-2W, equivalent to not entering standby at all).

    I've also speculated there may be hardware problems with some units, and that if RIM can wait out the warranty period before admitting any issues they'll avoid a large cost. Total speculation there... I have no idea if RIM would consider such a thing. I like to hope not. In the absence of facts communicated clearly by the company, we're forced to imagine such possibilities...
    02-07-12 04:00 PM
  14. Hgouck's Avatar
    Peter, Chaddface, Duggggg, jrohland, kennyliu, ScoopsDM, F2
    You all seem very knowledgeable. But you do know you are geeks?
    My problem is I enjoy learning this stuff and CB seems to be full of knowledgeable people. Thank you for sharing your wisdom willingly.
    02-07-12 04:25 PM
  15. FF22's Avatar
    I used to be a kind of geek. Computer programmer in a former life as well as a bacteriologist and then Adm Law Judge! (that's probably too much info and enough to ID me!!!! Now, trying to keep the gray matter saturated with blood flow.
    02-07-12 05:57 PM
LINK TO POST COPIED TO CLIPBOARD