Wacky battery antics

[grumpy]

I have a replacement SP2 that I am putting through its paces before I send the old one back. It has been fine, but it still seems to exhibit some of the anomalies of my original unit. Specifically, the battery level will spontaneously drop from 25.0% to 21.9%. Since both machines exhibit his same behavior, I am will to chalk it up to weirdness by design.

So, I decided to perform the Feb update. I first did a system refresh with the modified image (Jan drivers and 3368 display drivers) - I wanted to make sure that it worked while I had both Surfaces in my possession. After the refresh, I performed a windows update and all the updates successfully installed (including the firmware).

And now for the really weird part. Since this new update is supposed to improve the battery reporting, I decided to see what happens when it hits 25%. Sure enough, it dropped to 21.9% as it always had. But, then it dropped again to about 15% at which point, over the next minute, it crept back up to about 21.3%. It then seemed to discharge normally. Hmmm.... Just a I am writing this, I noticed the the battery was at 14.0% and the it again started to climb to 16.3%. I actually logged this behavior with hwinfo. Now it dropped to 10% (giving me the battery warning) and bounced back to 16%. This is really strange. And now down to 9% and back up to 15%. EDIT: I just restarted and the "yoyoing" seems to have stopped for now.... Drat.. never mind... just dropped to 6% and went into hibernation.

Perhaps I will try the update on my old unit to see if it does the same thing. I also wonder if it finally fixes the the battery resetting to 100% (which was the main reason for requesting the replacement).

 

[mennogreg]

Are you viewing the battery app on the taskbar or a third-party battery reporting program (because the one on the taskbar doesn't show decimal percentages).

For what it's worth, since the most recent firmware update, I have had no erratic battery level readings.

 

[grumpy]

Are you viewing the battery app on the taskbar or a third-party battery reporting program (because the one on the taskbar doesn't show decimal percentages).

Both. I am running HWInfo64 and looking at the taskbar values.

For what it's worth, since the most recent firmware update, I have had no erratic battery level readings.

Prior to the firmware update, I had only run down the battery to below 10% two times. Both times it would start hibernating at 8% (instead of 5%), which is the same behavior that I experienced with my original SP2. This is the first time I have run down the battery after the update and the "yoyo-ing" started once it dropped below 22%.

I thought this firmware update was going to be "safe"...

 

[grumpy]

I figured that some visual aids might be useful

 

[grumpy]

C'mon, I can't be the only one with these issues. At the very least there must be more people with this mysterious drop at 25%-22%. After all, both SP2s that I received exhibited that behavior. I can only surmise that the presence of that drop is causing the new firmware to freak out when it is encountered.

Anyway, after charging, the charge level was back to normal. I'll once again discharge it below 22% and see if the problem persist. I expect that it will...

I really don't know which SP2 I should send back. Either way, I probably need another replacement. I guess it will be easier to just send back the one with the serial number that they are expecting. I have already backed it up.

 

[mennogreg]

Looks like I have to offer a correction. It just happened to me to on the latest firmware update. Once it gets around 25%, it drops to 22%, then to 14%, then back up, then down, etc. It doesn't seem to affect my overall battery life (I'm still getting power as if it were counting down from 25%). I definitely see how this can be a bigger problem if you're hibernating earlier than you should (I have mine configured to hibernate at 6%). You can also go into power setting options and turn off notification of low battery level (you're still notified when you reach critical level), at least as a temporary workaround to get rid of the messages.

 

[grumpy]

Looks like I have to offer a correction. It just happened to me to on the latest firmware update. Once it gets around 25%, it drops to 22%, then to 14%, then back up, then down, etc.

Well, I am glad that I am not alone...Did you notice the 25% to 22% drop before the update? Both of my SP2s had this drop from the beginning. I guess it is easy to overlook if you are not looking for it.

I definitely see how this can be a bigger problem if you're hibernating earlier than you should (I have mine configured to hibernate at 6%).

The problem is that the level actually drops below any set hibernation threshold. Mine is set to 5% and the level starts to dip to 2% or 3% which initiates hibernation. When I wake it up, the level will rise to over 10%. I find that it is basically unusable below about 15% due to drop induced hibernation.

You can also go into power setting options and turn off notification of low battery level (you're still notified when you reach critical level), at least as a temporary workaround to get rid of the messages.

I might do that, but the real issue is the mandatory critical battery action. The critical battery level can only be lowered to 3%.

 

[mennogreg]

I definitely did not get this before the update, only reason why I'm so certain was I did several battery tests during that time to be absolutely certain how much battery life I can get out of this before relying on it alone for work tasks.

 

[mennogreg]

I also noticed that if I connect the power cable when the antics start, it shows the actual battery percentage immediately.

 

[grumpy]

I also noticed that if I connect the power cable when the antics start, it shows the actual battery percentage immediately.

Yup. The battery capacity returns to normal during charging. The graph I posted of the battery charging shows a nice linear increase in the battery percentage, until it hits the wormhole located at 22% and it abruptly jumps to 25%.

It doesn't seem like too many people are affected by this particular bug. It seems odd that MS is having such difficulty with getting the battery to report its capacity properly for everyone.

 

[Brent212]

I just looked at my battery indicator (desktop system tray), and it said I have 24% battery left, 83 hours. Wacky antics indeed.

 

[grumpy]

Well, the March update did nothing for my battery issues. If anything, it made that battery indicator more sporadic once it drops below 22%, immediately dropping below 10% before rising back up to 21%.