command: sudo tlp-stat -b
output:
— TLP 1.6.1 --------------------------------------------
+++ Battery Care
Plugin: generic
Supported features: none available
+++ Battery Status: BAT0
/sys/class/power_supply/BAT0/manufacturer = DP
/sys/class/power_supply/BAT0/model_name = bq20z451
/sys/class/power_supply/BAT0/cycle_count = 666
/sys/class/power_supply/BAT0/charge_full_design = 6330 [mAh]
/sys/class/power_supply/BAT0/charge_full = 5043 [mAh]
/sys/class/power_supply/BAT0/charge_now = 4936 [mAh]
/sys/class/power_supply/BAT0/current_now = 0 [mA]
/sys/class/power_supply/BAT0/status = Full
/sys/class/power_supply/BAT0/charge_control_start_threshold = (not available)
/sys/class/power_supply/BAT0/charge_control_end_threshold = (not available)
Charge = 97.9 [%]
Capacity = 79.7 [%]
my take:
this is an apple battery, meaning this command won’t load it up to a threshold I choose (not available)
charged currently at 97.9%, even if the gui says it’s 100%
capacity is 79.7%, what for me is a very high value, considering this is a 10 year old notebook (maybe it hasn’t been used much?)
your take?
The best way would in fact be testing it with an electronic load that applies a precise and well known load to the battery and integrates capacity until a matching shutoff condition is reached.
However, the majority of people do not happen to have access to such an instrument, so I’d say your suggestion is a close approximation of the best way, which could be augmented by adding simple measurements, which can be done by most people at home for a reasonable, quantifiable judgment.