Windows 10 laptop, 2.5 years old with its original 48 mWh battery installed. Up until recently the battery has always performed well and typically took around 2 hrs to charge from flat to full.
A few weeks ago I suddenly noticed issues where the battery would unexpectedly be critically low when waking the laptop from Sleep mode after several hours (e.g. overnight). Further testing has shown that this often happens when I put the laptop into Sleep OR Hibernate mode when the battery is 30-40% full or less - when I wake it up it's suddenly empty, or other times it shows ~60% and then rapidly drops to empty over a few minutes. It seems not to do it as often if I sleep/hibernate it with the battery mostly full, although today it showed a drop from around 60% to 40% after being in Sleep for 18 hrs. On the other hand, if I charge it to 100% and shut it down completely, it seems to hold charge OK and will still be ~98% when I boot it up in the morning.
I've been generating a lot of battery reports (powercfg /batteryreport) but having trouble interpreting the erratic results. "Full Charge Capacity" seems to fluctuate a lot from day to day. I am pretty sure it charges fully to ~48 mWh, regardless of what it thinks the "Full charge Capacity" is, because it still takes about 2 hrs from flat before the orange LED on the front turns green (even if the system tray icon sometimes says "5 min remaining to full charge" for the last 20-30 min and the battery report ends up >100%). This makes me think the software battery monitoring is out of calibration. But I have tried the whole full charge/full discharge/full charge cycling thing and I don't know what to do next to test whether this is purely a software issue or if the battery really is failing.
Following internet advice I also removed the device "Microsoft ACPI-Compliant Control Method Battery" and reinstalled it a couple of times. This doesn't seem to have made much difference.
What should I try next to help diagnose the problem?
Tech Support Guy System Info Utility version 1.0.0.9
OS Version: Microsoft Windows 10 Pro, 64 bit, Build 19045, Installed 20210607014636.000000+660
Processor: Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz, Intel64 Family 6 Model 165 Stepping 2, CPU Count: 12
Total Physical RAM: 16 GB
Graphics Card: Intel(R) UHD Graphics, 1024 MB
Hard Drives: C: 930 GB (492 GB Free); D: 931 GB (589 GB Free);
Motherboard: IT Channel Pty Ltd NP50DE_DB, ver Not Applicable, s/n Not Applicable
System: INSYDE Corp., ver INSYDE - 2, s/n NKNP50DB0000I00274
Antivirus: Windows Defender, Enabled and Updated