How to accurately measure laptop battery life in Linux?

czak@lemmy.ml to Linux@lemmy.ml – 53 points –

tl;dr: I'm looking for something like AccuBattery, but for Linux

What do you use to measure laptop battery life in Linux?

I can easily get a momentary estimate of battery life. But this fluctuates based on load, screen backlight etc.

I'm looking for something that will collect my usage patterns over time - load, #processes, screen backlight, ... - and allow me to predict remaining runtime more accurately.

I'd love for the data to be parsable, so that I can analyze it myself and e.g. find the "worst offenders" - processes affecting battery runtime the most.

Thank you for any tips!

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Can't help you directly, but powertop can be used to monitor/tweak momentary power usage.

Thanks, I do like powertop. I think it's pretty good for short measurements, e.g. over 30 seconds:

% sudo powertop --time=30

The battery reports a discharge rate of 4.17 W
The energy consumed was 125 J
The estimated remaining time is 11 hours, 4 minutes

But in the real world I will not be getting 11 hours of runtime. The moment I start a browser or play a video, power consumption goes way up.

Well, no program can accurately predict how you are going to use your laptop in the next hours. The best you can do is sample a given reference period and assume it'll be the same but you have already noted the problem with that.

I'd recommend you monitor total power draw while using your laptop. It's inversely proportiaonal to battery life: If you could reach 10h at 5W, you'd only reach 5h at 10W, 2.5h at 20W and so on; you can think of it as a metric for battery drain.

Agreed, that sounds like the way to go. I was hoping there was already something to do the monitoring for me :)

If you're technically inclined, a simple bash script with a for loop could dump the time and discharge rate to a text file every minute. Then you could copy/paste that into LibreOffice calc and do yourself some pretty graphs, or whatever.

edit: just found a tool called powerstat which looks like it does sampling over longer intervals.

sudo apt install powerstat

Interesting, hadn't heard of powerstat. I'll be checking that, thanks!