Battery calibration reduced 100% capacity, unexpected result

JL_01
JL_01 Member Posts: 9

Tinkerer

edited August 14 in Predator Laptops
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I attempted to calibrate my battery yesterday, August 13, 2025. As shown in the picture, the 99% charge was 85,917 mWh. However, after calibrating the battery, the full capacity at 100% dropped to 80,865 mWh. This is weird, as it represents a significant decrease in capacity. I regret that I performed the battery calibration.

Answers

  • Puraw
    Puraw ACE, Member Posts: 18,640 Trailblazer

    Hi JL_01 "Battery Calibration" is a misnomer, what it is supposed to do is perform the One Full Charge Cycle required once a new battery is installed and once Windows has been reinstalled or reset. No more, only one time to register the full charge capacity in BIOS and MS ACPI Battery protocol. With a new laptop not needed as Acer has done that already in the factory. I don't recommend Acer Care Center or any of the 'Calibration-Optimization-80% Charge limiting'' in PredatorSense. Just do the full charge cycle after you have reinstalled or upgraded Windows: Disable Fast Startup in Windows Edit Power Plan, update BIOS, charge the battery to 100% and wait an extra 10 minutes then drain (use) your laptop with the power adapter unplugged till the system shuts down on its own (don't suspend, don't touch the power button and do not shut down with the Start-Power icon), just close the lid, don't worry you won't lose data and the battery will be fine. Plug in the power adapter and charge till the amber battery LED turns blue and wait a few minutes. Boot to Windows, that's it

  • JL_01
    JL_01 Member Posts: 9

    Tinkerer

    @Puraw That's exactly what I did. I charged the battery first to 100% but Idk why 99 percent is shown in the report. Then, I drain the battery until the system shut down on its own (I didn't touch anything). I just closed the lid and left it drained for about 20mins then plugged in the power adapter and charge it till 100%. After that, I open my laptop and check the battery report, but sadly, it drops the full capacity of the battery, from 100% 86,440 mWh it drops to 100% 80,865 mWh.

  • Puraw
    Puraw ACE, Member Posts: 18,640 Trailblazer
    edited August 14
    1. Disable Fast Startup: Control Panel → Hardware and Sound → Power Options → Choose what the power buttons do → Change settings that are currently unavailable → uncheck Turn on fast startup → Save.
    2. Remove charge limits and tools:
      • PredatorSense: Allow 100% (disable 80% cap).
      • Acer Care Center: Don’t run “calibration/optimization” for this process.
    3. BIOS sanity pass:
      • Update BIOS: Get the latest for your exact model from https://www.acer.com/support..
      • If already latest: Load Setup Defaults in BIOS (F9) → Save & Exit (F10).
    4. Refresh Microsoft battery drivers:
      • Device Manager → Batteries:
        • Uninstall device: Microsoft AC Adapter
        • Uninstall device: Microsoft ACPI-Compliant Control Method Battery
      • Reboot: Windows will reinstall them.
    5. Do one clean full charge cycle (gauge sync):
      • Charge: Plug in, charge to 100%, wait an extra 10–20 minutes.
      • Discharge: Unplug and use until it powers off on its own. Avoid manual shutdown; if you must step away, just close the lid.
      • Rest: Leave off 15–30 minutes.
      • Recharge: Plug in, charge to 100%, wait a few minutes at full, then boot.
    6. Paste this in the command prompt: powercfg /batteryreport and open the report with your Edge browser, press Ctrl + P or right click and select "Print to Microsoft PDF", attach the report to your reply, type @Puraw or use "Quote" when you reply so I will get an alert.
  • JL_01
    JL_01 Member Posts: 9

    Tinkerer

    edited August 14

    @Puraw TBH, I did all of that, but it still degraded my full capacity.

    Don't mind the design capacity. When this laptop is new the full capacity is only 86,440 mWh but it show 90,614mWh on the design capacity so I think when I bought this laptop the battery is already degraded. I didn't return it since I only notice when 7days passed which is they're not accepting return so I just let it go. Then now it drops to 80,865 mWh because of the battery calibrate that I performed yesterday I thought its fine to do it, that's why I tried to calibrate it.

  • Puraw
    Puraw ACE, Member Posts: 18,640 Trailblazer

    Before you open a repair ticket, clear all possible software limits.

    • In Acer Care Center and PredatorSense, make sure any “battery charge limit” or “optimization” options are disabled.
    • If those apps have been uninstalled, check services.msc for any Acer‑branded battery or power‑management services and stop/disable them.
    • Remove any third‑party battery monitoring/management tools that might interfere with charging or reporting.

    Once that’s done:

    1. Run one clean 20 % → 100 % → 20 % cycle to let the gauge stabilise.
    2. Generate a fresh powercfg /batteryreport and note Full Charge Capacity and observed runtime.

    If runtime is still ~1.5 h under normal load after that, contact Acer Services in your country or open an online warranty repair ticket. At that point, with a new system, a short runtime may indicate a pack fault — and it’s best handled under warranty.

  • Axxo
    Axxo Member, Ally Posts: 2,271

    Battery calibration is a process to improve the accuracy of the battery's charge indicator, not a way to increase its capacity. If battery calibration is causing a reduction in perceived battery capacity, it's likely due to an issue with the battery itself or incorrect calibration procedures.
    Explanation:
    What Battery Calibration Does:
    Battery calibration helps the operating system accurately display the remaining battery charge percentage and remaining time. It involves fully discharging and then fully charging the battery to recalibrate the battery's internal "fuel gauge".
    Why Capacity Might Seem Reduced:
    If a battery is already degraded, calibration might expose its true, reduced capacity. A battery's capacity naturally degrades over time and with usage.
    Possible Issues:
    Battery Degradation: If the battery is old or heavily used, it might not be able to hold as much charge as it used to. Calibration will reflect this change.
    Incorrect Calibration: Performing the calibration process incorrectly can also lead to inaccurate readings. It's important to follow the specific instructions for your device.
    Software Issues: Sometimes, software glitches or outdated drivers can affect how the battery is displayed. Ensuring your system is up-to-date is crucial.
    -----------------------------------------
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