This is batfetch (former poweranalyser), a simple bash script to read the current battery discharging cycle and estimate the battery time left.

simply execute the bash script (sudo is not needed).

use batfetch -c 1 to analyse previous cycle

use batfetch --getcycles to see how many cycles are available to read

Running on battery since 27/12/23 at 17:55:46 with 86%
until now (current cycle) with 27%
during this cycle the computer was sleeping for 18 hours, 18 minutes, 13 seconds

Running on battery for:         6 hours, 0 minutes, 25 seconds
Battery consumed:               59 %
Average power usage:            4.87562 W

Current power usage:            4.894 W (discharging)

Time to empty:                  2 hours, 45 minutes, 16 seconds
Battery cycle duration:         8 hours, 45 minutes, 41 seconds
Battery full-span:              10 hours, 10 minutes, 53 seconds

The output is as follows:

• Running on battery for time running on battery (minus suspend and shutdown time, see notes)
• Battery consumed the % of battery consumed in the analysed cycle
• Average power usage average power consumption (calculated based on running on battery)
• Current power usage power usage from ACPI (it might not be available in your system)
• Time to empty available time running on battery
• Battery cycle duration the full cycle duration since started running on battery until battery is empty
• Battery full-span based on average, the full battery timespan

The Running on battery for calculates the time that the laptop has been running in battery by looking in the journalctl log for suspend and shutdown states. Therefore, this value does not account for the time that your laptopis not running (in suspended mode or shutdown). This seems to give a good and accurate calculation of the time remaining of the battery.

This script has not been tested in many computers and distributions. I have used Arch Linux (Thinkpad Carbon X1 gen 9) and tested in Ubuntu (Asus Zenbook).