Simple power use optimization on Debian - now down to sub 4 watts / 12 hours runtime on 90% battery

Okay, got some good stuff here, at least, I hope!

I’m in Kyiv, and we get power cuts, so I’ve been looking into this matter with a direct and immediate interest : -)

So, first, you must install “powertop”. It is absolutely central to power optimization work, for both information and critical functionality that it provides.

The first big surprise I had was how much power is consumed by some of the software I run.

Now, to put this is context, my 12th gen now - now I know what I’m doing - draws just under four watts, which gives me about twelve hours of run-time with a 90% charge.

Well, I run Tor as a service, and that by itself consumes about 1.5 watts! and it’s completely useless when the power is out because there’s no wifi. When the power cuts, first thing I do is stop Tor.

Similarly, my normal text editor is from Windows and runs under WINE; which turns out to take something like 3 watts to run! so now when the power is out, I use a native text editor.

You have to fire up powertop, and look at what software is consuming power.

Next, powertop if you hit tab a couple of times has a list of “good” and “bad” config on your machine, with regard to power consumption.

If you issue “powertop --auto-tune”, they will all be configured to “good”. This makes a substantial difference - the only problem is, the changes are not permanent, They’re lost on reboot. I’ve yet not much looked into how to make the changes permanent.

Next, powertop does not show you how much power is being consumed by peripherals. To my astonishment, the USB mouse I have consumed 3 watts - which is now not far off what the entire laptop consumes! it was roughly halving my battery life.

Finally, note that the backlight seems to draw very little power. Putting it at about 20% hardly makes a difference.

So, here’s the hit-list;

  1. powertop --auto-tune (not permanent - needed after every reboot)
  2. remove USB peripherals
  3. shut down any non-essential software/services
  4. check with powertop which processes are drawing what power, so make sure there are no surprises

This is great to hear this is working for you. I don’t “officially” recommend this on docs because of the nature (mission of powertop), but yes, this works really well so long as everyone understands I cannot officially support this if it fails.

Conversely, I have used it successfully in the past. Good stuff! :slight_smile:

Stay safe and thanks for sharing your experience with this.


I do not understand this. What do you mean?

Thankyou! no worries, though. Kyiv is huge, the chances of being hit are minute, unless you live within about 50m or so of a target. In that case, it is wise to move. There are a couple of residential blocks I’ve seen hammered by drones/missiles which missed their targets, all in close proximity to that target. The people inside, or living in the top floor or two, died.

Officially, PowerTOP is designed to " Powertop is a tool that helps to diagnose various issues with power consumption and power management."

Unofficially, it can absolutely be used to set custom tuning. I hesitate to recommend using it for persistent tuning because unlike a TLP default, PowerTOP requires choices to be made to be effective. And if something is done incorrectly, that falls back to my recommendations…on using a diagnostic tool as a power saving tool.

I think it’s great and I have done it myself, but I do not provide the instructions myself as it will lead to additional “now it’s doing this…” type issues.

To make matters even muddier, Intel has one stance on using it while others have taken my stance. PowerTOP is awesome. And if it works for you anyone, even better. I simply don’t mention it outside of diagnosing due to my own experiences with some users getting lost with it.

Hopefully that made more sense. :slight_smile:

1 Like