I have 6 batteries for my laptop. I used powercfg /batteryreport to check "Full Charge Capacity" for each of them.
Then I wrote a quick Excel VBA script that enters total elapsed time in a cell every 30 seconds and saves the file, and counts down the seconds in another cell to the next save. After the battery runs out and the laptop powers down, I plug it in and power it back up, and check the last-saved total elapsed time. I ran that script for each of the batteries after charging them up to full charage.
That may not be a realistic measure of real-world battery life, but I think it's useful for comparing the batteries to each other, so that I know which ones to take with me when I'm not taking all 6.
I'm seeing no correlation between powercfg /batteryreport "Full Charge Capacity" and the total elapsed time measured by my script. Any idea why that might be?
BTW all 6 batteries are genuine branded OEM.