Engineering Windows 7

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Windows 7 Battery Notification Messages

Windows 7 Battery Notification Messages

Over the past week we have seen a little bit of blogosphere activity regarding Windows 7 and batteries, specifically the new Windows 7 message “Considering replacing your battery”. Since this is related to the engineering of Windows 7 we’re going to use this blog to provide an update to people. As we have talked about many times, we have a relentless focus on the quality of Windows 7 and we take seriously any reports we receive that indicate a potential problem that could result in a significant failure of the OS. In a previous post we talked about the steps we take when we receive a bug report, in particular when we start to see several reports that appear to be the same. For the past week or so we have been diligently working through these steps and more to see if there is anything in Windows 7 we need to address regarding this issue. At this time we have no reason to believe there is any issue related to Windows 7 in this context.

Several press articles this past week have drawn attention to blog and forum postings by users claiming Windows 7 is warning them to “consider replacing your battery” in systems which appeared to be operating satisfactorily before upgrading to Windows 7.  These articles described posts in the support forums indicating that Windows 7 is not just warning users of failing batteries – as we designed Windows 7 to do this – but also implying Windows 7 is falsely reporting this situation or even worse, causing these batteries to fail.  To the very best of the collective ecosystem knowledge, Windows 7 is correctly warning batteries that are in fact failing and Windows 7 is neither incorrectly reporting on battery status nor in any way whatsoever causing batteries to reach this state. In every case we have been able to identify the battery being reported on was in fact in need of recommended replacement.

Using all the tools at our disposal including contacting customers reporting this issue on forums, customer service communications, partnerships with our PC makers, and of course the telemetry in Windows 7, we have been monitoring reports and discussions regarding this new feature, trying to separate reports of the designed behavior from those that might indicate an issue with Windows 7.  In the latter cases we are trying to understand the scope of applicability and obtain hardware on which to reproduce a faulty behavior.   To date all such steps indicate that we do have customers seeing reports of battery health issues and in all cases we have investigated Windows 7 has simply accurately detected a failing battery.   Before I go into our status on this particular issue, we should review the details behind this new feature.

One of the most obvious components of PC battery life (the runtime you get on battery power) is the battery itself. PC batteries inherently degrade in their ability to hold a charge and provide power (as is the case for all rechargeable batteries). The cause of this is complex and includes irreversible changes in battery chemistry, and increased internal resistance among other things and those in turn are dependent on the design and manufacturing of the battery. This degradation translates into less battery life for the user over the life of the battery in the PC.  Ultimately, batteries must be replaced to restore an acceptable battery life.  A quick check of mainstream laptops will show that batteries usually have a warranty of 12 months, which is about the length of time when statistically we expect to see noticeable degradation (meaning that you start to notice the need to charge more frequently). Those of us that have owned the same laptop (or mobile phone, or music player, or anything else with rechargeable batteries) for a couple of years and taken it through regular charge cycles have no doubt “felt” the decline in battery life though we might have attributed to any number of factors since we did not have any information available to us otherwise.

Windows 7 makes use of a feature of modern laptop batteries which have circuitry and  firmware that can report to Windows the overall health of the battery. This is reported in absolute terms as Watt-hours (W-hr) power capacity. Windows 7 then does a simple calculation to determine a percentage of degradation from the original design capacity. In Windows 7 we set a threshold of 60% degradation (that is the battery is performing at 40% of its designed capacity) and in reading this Windows 7 reports the status to you.  At this point, for example, a battery that originally delivered 5 hours of charge now delivers, on average, approximately 2 hours of charge.  The Windows 7 the notification is a battery meter icon and notification with a message “Consider replacing your battery”.  This notification is new to Windows 7 and not available in Windows Vista or Windows XP.

Consider replacing your battery - Windows 7 notification

PC batteries expose information about battery capacity and health through the system firmware (or BIOS).  There is a detailed specification for the firmware interface (ACPI), but at the most basic level, the hardware platform and firmware provide a number of read-only fields that describe the battery and its status.  The firmware provides information on the battery including manufacturer, serial number, design capacity and last full charge capacity.  The last two pieces of information—design capacity and last full charge capacity—are the information Windows 7 uses to determine how much the battery has naturally degraded.   This information is read-only and there is no way for Windows 7 or any other OS to write, set or configure battery status information.  In fact all of the battery actions of charging and discharging are completely controlled by the battery hardware.  Windows only reports the battery information it reads from the system firmware. Some reports erroneously claimed Windows was modifying this information, which is definitely not possible.

As mentioned, every single indication we have regarding the reports we’ve seen are simply Windows 7 reporting the state of the battery using this new feature and we’re simply seeing batteries that are not performing above the designated threshold. Below we’ll talk about the data we have to support this point of view. It should stand to reason that some customers would be surprised to see this warning after upgrading a PC that was previously operating fine. Essentially the battery was degrading but it was not evident to the customer until Windows 7 made this information available. We recognize that this has the appearance of Windows 7 “causing” the change in performance, but in reality all Windows 7 did was report what was already the case.

The following data points contributed to our understanding of the reports we are seeing. Please keep in mind that all the telemetry we see is opt-in, anonymous, and respects our privacy policy.

  • We have seen no reproducible reports of this notification on new hardware or newly purchased PCs. While we’ve seen the reports of new PCs receiving this notification, in all cases we have established that the battery was in a degraded state.
  • Our OEM partners have utilized their telemetry (call center, support forums, etc.) and have let us know that they are seeing no activity beyond what they expect. It is worth noting that PC manufacturers work through battery issues with customers and have a clear view of what is to be expected both in general and with respect to specific models, timelines, and batteries.
  • We’ve gone through all the major online support and self-help forums and when appropriate have worked to follow up with any reports of this notification being presented in error. Through this we have identified no reproducible cases where the battery or PC was new and have only learned of batteries that were degraded in capacity.
  • In our telemetry from RTM code customers, only a very small percentage of users are receiving the “Consider replacing your battery” notification, and as expected, we are seeing systems older than ~1.5 years.  We’re seeing relatively fewer notifications compared to pre-release software as the average age of the system decreases.
  • Microsoft has received 12 customer service incidents in addition to pulling 8 additional incidents from various forums. To date (for a total of 20 incidents), none of these have shown anything other than degraded batteries. 
  • Microsoft has been using the technet community moderators to assist in further contacting customers reporting on this notification and we’ve assigned additional customer service personnel to be ready. However, of the 30 or so contacts we have received we have not learned of any new facts or conditions with respect to this notice.
  • During pre-release testing of Windows 7 we saw almost precisely this same experience with customers in terms of the display of the notification. In fact, in looking at the hardware distribution of pre-release testing we saw an ever so slightly higher number of systems receiving this notice. This follows from the fact that a large set of customers are buying Windows 7 with new PCs or using the upgrade provided with a recent Windows Vista PC.
  • When looking at the telemetry reports for the machines that have reported displaying this notification we have seen nothing in additional reliability data that indicates any other system anomalies.
  • While the information regarding battery status is provided read-only to the operating system through ACPI, we performed a thorough code-review and verified that there exists no code that is capable of modifying battery status information.

This data would confirm our point of view that we are seeing nothing more than the normal course of battery degradation over time. The transparency provided in this new Windows 7 feature produced a notice that previously was not available to customers and did so shortly after upgrade. This is the root cause of the urgency with which we’ve seen postings, but does not change the reality of the condition of the battery. We have no confirmed cases of new machines with the as-purchased batteries.

As we always say with regards to any reports on the quality of Windows 7, we are going to continue to be diligent and use all the tools at our disposal to get to the bottom of a report that has the potential to require a code change we would distribute to customers. We are as certain as we can be that we have addressed the root cause and concerns of this report, but we will continue to monitor the situation. In particular, we will continue to have focused communication with our OEM partners as they monitor their customers and PCs over time.

Finally, if you believe you are receiving this error and your battery is new or believed to be in great shape we would encourage you to report this to us or your original PC maker. You are welcome to send me mail through the contact form on this page, use the TechNet forum, the Microsoft Answers forum, or visit where you can get additional information about how to contact Microsoft assisted support in your region.



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  • I have the same problem on my ACER aspire 6935G with windows 7 64bit business.

    Before I have 2 hours of baattery, now only 40 minutes.

    As Microsoft said that maybe a Bios problem I updated my to the 1.13 (september 2099) and the problem is still there.

    However now speedstep works correctly.

    Before CPU stay at 1.1v and 2GHz or 1.6 GHz.

    Now vcore is @ 1.1 , 1.0 , or 0.9 and the frequency is 2, 1.6 or 0.8 GHz.

  • Thank you for this insightful information.  It explains my challenges with battery life, not with Windows 7.

    Could you expose the battery firmware information to the user interface, please?

    It would be great diagnostic tool, for any OS, not just Windows 7: "The firmware provides information on the battery including manufacturer, serial number, design capacity and last full charge capacity."

  • That explanation is simply absurd. My netbook is a mere six months old, and it is already complaining about "consider replacing the battery". That happened after installing Windows 7. Whay say you Microsoft?

  • I fail to see the issue. Annoying as the little notification may be -- how about just ignoring it?  

    All things considered, as Micro$oft product users for years, we've clicked through far worse on a regular basis (i.e. EULAs, etc.)

  • My battery life went from about 2.5 hours before installing Windows 7 to 40 minutes after.I don't think my battery could have deteriorated that much in the few hours it took me to install.....

  • While the computer is on, and Design Capacity is = 0, and you unplug the AC, plug it back in, and Design Capacity changes from 0 to "Unknown", THEN the "replace your bettery" message appears. Yes, this is a brand new battery, and yes I've tried multiple BRAND NEW batteries. Same result. Microsoft needs to address this scenario (when the computer is running, and the battery characteristics of Design Capacity change from 0 to unknown, it will throw the "Consider replacing your battery" exception).

  • hey putz - I know tech geeks and those who talk "businesspeak" are generally illiterate, but a computer is not an "ecosystem" - there is nothing "organic" about it.  I wish you idiots would stop molesting the English language

  • A sampling of 20 computers is not indicative of the whole population of PCs out there -- but I don't think Steve is saying it is or that there couldn't be real issues lurking.  If your battery is indeed new, and you're having this issue, it's possibly either a bad battery or some other BIOS type issue.  Use the methods Steve talks about to report the issue so MS can work with your OEM to find out the cause.  Or at the least, include your make and model when you're posting your information so everyone can start to see a trend and pick up on the misbehaving models.

    For every 1 person that complains, there are many more of us that are very happy with the behavior.  On both of my Lenovos, two family Dells, and a new Acer tablet, the behavior is exactly what I expect.

    Regarding reduced battery life, again, you still should try to work with OEM (or MS) support.  All of these same laptops perform better on Win7 with minimal battery life change.  You can always get slightly better battery life by disabling Aero, etc.  Some systems even can do that dynamically.  But it varies a lot by GPU and BIOS... for me, it's such a small hit and Win7 is so much faster that I can get more done in less time.

    If your laptop is older, you might also want to open it up and make sure the heat sink is firmly attached and the holes not clogged with dust.  Nothing is worse for a laptop, and some models are definitely notorious for this after just a couple of years.

  • How I "fixed" my battery.

    Soon after I installed windows 7 on my laptop I got the "Consider replacing your battery" message.  I dual boot with Vista and there the battery was fine.

    So I removed the battery and restarted the computer, shut it off again and put the battery back in and since then Windows 7 never complained about the battery again.

  • I have a HP6710b and all I can say is that with Vista and Win7 Beta 2 it worked for 2-3 hours...after a week or so of Win7 RTM (32bit) it dropped to 15min (at most 1 hour on power saver)...reported the same issue to HP using the same username and have had batteries replaced on another HP6735s with the same problem.

    I have a premium MSDN subscription (not cheap) and it hurts me that microsoft is calling me a liar (and as I can see others too).

    Being a developer I will continue to use Microsoft technologies, however this keeping up I will reconsider my attitude towards Java. Android seems a better platform every day, and Chrome OS is just beyond the corner...

  • My laptop used to get about 2hrs of battery life.  I do not get this warning, but i now only get about 20minutes of battery life since upgrading to Windows 7.

  • Many people continue to miss the point entirely. Why, it almost seems deliberate.

    Let's assume for a moment the fault is my battery. Let's assume that it is indeed "bad" or "marginal." The issue is *NOT* that Windows 7 tells me I have a bad or marginal battery: Were it that simple, I would simply ignore it and go on my merry way. The issue is that that battery will only provide me with 20 minutes of off-AC life, which in very short order degrades to 15 minutes, then 10, then 5 before shutting down the machine, this even if I have my computer set to do nothing upon battery drain. (That is to say, it is NOT hibernating or sleeping: it shuts down, and will not power up, even to POST.) That *VERY SAME* "bad" or "marginal" battery will yet happily provide me with a nice juicy 45 or 60 minutes of off-AC power on the *VERY SAME* computer running Windows XP or Vista.

    So, either Windows 7 is doing something odd with the way it handles battery, or something is causing spikes that are draining the battery way too fast ... either way, a problem with the OS, *NOT* my laptop, my BIOS, or anything else. The only variable is the OS.

    Further, take a newly unwrapped battery and install it, and it will exhibit the same behavior: Again, Windows 7 isn't simply giving me a message about my battery, it is actually running the battery down.

    These are the issues being encountered by those of us who have dealt with it. Please stop insisting that it's simply new Windows 7 functionality, telling us about the reality of our bad batteries. The proper way of thinking about it is that it is new Windows 7 functionality, correctly reporting the bad batteries that it has helped to create.

  • When I tested my first windows 7 beta in my acer aspire one netbook, it said that the battery was present but not charging. The issue was resolved when I upgraded the BIOS. Another issue that might be resolved with BIOS or an app is that if you bought a laptop with Vista it might have some OEM software to regulate the fan, that is, turn it off for the most part. When you upgraded or fresh installed Windows 7 that software is gone and now the fan might be spinning all the time, consuming battery faster. You just need to reinstall that utility or see if the manufacturer has a BIOS update that now regulates fan through BIOS. Also, when you read battery life you have to consider that the calculation is based on the last few minutes of user activity, so if you were watching a video, Windows 7 will report all of a sudden less minutes left, but if you stop the video, after a few minutes Win7 will report more minutes available. Does this mean that the battery magically recharged itself? Of course not. So, measure battery life not by what the OS tells you but by real usage. Personally I have tried in my small acer aspire one four OSs: XP, Win7, Ubuntu and OSX snow leopard (yes it works) and battery life has been virtually the same with them all. If there was a problem with Windows 7 consuming more battery this issue would happen with ALL windows 7 installs. Is this the case? No. Since it only happens to a few systems, then is hardware specific, and since no OS can do more than just read battery status, and battery operation is fully controlled by hardware and BIOS, then the logical conclusion is that Windows is not to blame. As simple as that. So upgrade your BIOS, check if there was an utility to regulate fan speed that you might need to reinstall, or if the problem disappears when you buy a new battery, then, folks, is the battery/bios/hardware.

  • I totally agree with kev99sl, because just now, I booted my laptop, and my brand new battery, when going to retreive the battery information, totally returned really weird numbers, then windows crashed (hard froze). I really do believe that something is going on now, since the design capacity was 90,395,233 and the battery condition was at infinity % and the total capacity was 9, and Total Capacity was 40,923. Regular values of my battery should have been: Design Capacity: 0, Total Capacity: 55,564, Battery condition: Unknown, Charge Cycles: Unknown.  So in some rare occasion, something is being mishandled.

  • Typo: I meant to type Total Capacity was 9 and Battery Capacity was 40,923.

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