My Acer Aspire S7-392 runs well on mains, but on battery shuts down suddenly and without warning. And I mean no warning, it is like someone yanked the power from a desktop PC. Windows does not hibernate and no unsaved work is recoverable. The battery icon will be showing well over 90% in the notification area of the taskbar. I get anything from about 3-15 minutes (random) before power goes.

I am running Windows 8.1.

In Device Manager, the "Batteries" hardware seems ok. There are two entries:

  • Microsoft AC Adapter

  • Microsoft ACPI-Compliant Control Method Battery

    Neither shows any particular problem when you view the properties. I've carefully checked my power plan in Control Panel and again, nothing looks wrong.

Is there a Windows Service that needs to run to communicate battery levels from the hardware to the OS? Is there any hardware diagnostics I can run on the battery itself?


Following on from one of the comments, here is the output from batterinfoview:

  • Battery Name AP13F3N
  • Manufacture Name SANYO
  • Serial Number 295
  • Manufacture Date
  • Power State Discharging
  • Current Capacity (in %) 76.9%
  • Current Capacity Value 34,088 mWh
  • Full Charged Capacity 44,340 mWh
  • Designed Capacity 47,100 mWh
  • Battery Wear Level 94.1%
  • Voltage 7,995 millivolts
  • Charge/Discharge Rate -6,098 milliwatts
  • Chemistry Lithium Ion
  • Low Battery Capacity (1) 2,430 mWh
  • Low Battery Capacity (2) 3,098 mWh
  • Critical Bias
  • Number of charge/discharge cycles 0
  • Battery Temperature
  • Remaining battery time for the current activity (Estimated) 05:03:08
  • Full battery time for the current activity (Estimated) 06:34:08


Am busy discharging my battery in order to recharge and see if this improves, as suggested. But I also remember recently stopping the following service:

Sensor Monitoring Service (SensrSvc)

about four weeks ago because I was finding the inconsistent dimming/brightening of the screen and buttons annoying. About that time, I started having the laptop dying when running on battery as described, though I didn't connect the two thoughts till now. I've now reset this service to "Automatic (Delayed Start)" and have been operating for over 60 minutes (so far) on battery without failure. I realise this is tentative, but that service may be part of the problem. Will continue to report...


The laptop continues to give trouble when running on battery, so the "Sensor Monitoring Service" appears to be a red herring. The battery continues to report high charge levels when the laptop dies very suddenly. A recommendation from the Acer support website is to "fully discharge the battery" which is difficult to do...because the laptop dies when running on battery! Have contacted Acer Support, will try to discharge battery overnight and will report back...


Finally got a response back from Acer Support who also agreed that the battery metrics looked fine. The solution was to reset the battery by placing a paperclip into a small hole on the reverse of the laptop case (next to a battery symbol). They recommended 8-10s, but I felt the soft "click" of a button being pressed when I inserted the paperclip and left it in place for ~30s.

After this, I went into Power Options and created a new plan called "No Turn Off On Battery". All options were set to never turn off (screen, processor, putting computer to sleep, etc). The laptop was left running on battery overnight which meant the battery would be completely drained. In the morning I recharged the battery (without powering the laptop). Since then (touchwood) the battery and laptop appear to be behaving themselves.


Crumbs, problem has started again. Had been working for about 120 minutes on battery when suddenly conks out. Power up and in less than 60s (sometimes as short as 3-4s) the laptop conks out. So all the following appear to be NOT part of the solution!

  • Power Options (specifically creating a "No Turn Off On Battery" plan)
  • Sensor Monitoring Service

and the problem DOES appear to be specifically the battery that is problematic. What irks me the most about this is that Windows doesn't even Hibernate, so this means the OS is not even getting a low/critical battery alarm. Very bad!

After experiencing the above repeatable failures after just a few seconds, I again reset the battery using a paperclip and the laptop immediately started working again (now into 15 minutes running-time on battery).

My "going-forward" plan is now going to be to reset the battery when I next get this issue. Unfortunately this means I'm going to be on tenterhooks every time I use the laptop on battery, waiting for the battery to fail, so will probably limit battery-only usage to non-critical tasks.


See the accepted answer and comments. I bought a general purpose multi-bit screwdriver (in my case Stanley 20 Piece Multi Bit Screwdriver Set), and tightened all T6 Torx screws on the reverse of the laptop. So far problem has not re-appeared.


I've now had many months of trouble-free operation, including running the laptop on battery for hours. The problem is definitely the T6 screws only (and not the battery). The somewhat negative "UPDATE 5" has been updated accordingly.

  • 1
    Try running BatteryInfoView and edit the information into your question. – bwDraco Dec 3 '15 at 23:11
  • @Tyson: Well, the thought did occur to me, of course. But that's also easy to say. Surely there is some diagnostic I can run to prove that the battery is faulty or not? This is a high spec laptop, less than one year old. – AlainD Dec 3 '15 at 23:11
  • It's exactly what happens when batteries fail at end of life tho – Tyson Dec 3 '15 at 23:13
  • If it's less than one year old, chances are good it's under warranty. Call your computer manufacturer and let them know your battery is faulty and needs to be replaced under warranty. – bwDraco Dec 3 '15 at 23:14
  • 1
    The output provides no overt indication of battery failure—it might simply be miscalibrated. See if cycling it from full to empty and back several times helps. If this does not help, contact the manufacturer. – bwDraco Dec 3 '15 at 23:19

i had the same problem. google acer s7 accu problem. the solution is tighten the screws on back side beause they are self loosing and there is a safety detection system in place to switch off accu when open. you will need a T6 or TX6 Screwdriver.

| improve this answer | |
  • 1
    With a high degree of confidence, I can now say this is the answer. After tightening the T6 screws very hard, I've operated the laptop multiple (and extended) times without failure. The issue appears to be endemic to these Acer laptops across multiple models and is discussed more here: community.acer.com/t5/S-and-R-Series/S7-392-fails-on-battery/… – AlainD Mar 10 '16 at 22:41

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