A friend is flying to the US from Europe and asked me a very thought-provoking question, which I am not remotely able to answer with substance so I am asking it here:

• How to absolutely maximise battery life on an Ubuntu (laptop) install?

do not rush to mark this as duplicate, there is an important point here: does -GNOME- help or worsen battery life?

Let me provide some context:

• The only task he needs to perform is: edit text files in Vim.

• He is unsure whether running GNOME will drain his battery life more or actually save him some battery life given the smarts of GNOME's power management features like "switch this peripheral to -power save- after X minutes..." (GNOME might just be a configuration front-end for settings that are governed by command-line utils for all I know?)

• He could perfectly well boot the system in text-only mode and use the automatic 6 virtual consoles for his needs, if that's a saving at all over running tmux (I think so because of all the smart buffering/history/etc the latter does by default?)

Exactly how would you advise him to run his laptop during his flight?

What I told him already:

• power off WiFi in the BIOS, not from the "GUI"
• power off Bluetooth
• switch off the courtesy light and use low monitor brightness
• play music off of his phone, not mp3blaster
• do not use his tiny portable mouse (and do not attach any other USB gimmicks like "screen light", etc)
• stop development services he will not be using, especially apache2, tomcat, dovecot, postgresql, etc.

Potentially: - switch off his cron jobs? (he does an rsync + tar + 7za of his "work in progress" every so often)

I think the above is standard stuff one could get off StackExchange, and with many duplicates... the core of this question is, I think:

__ will running Ubuntu in text-only mode be a saving in terms of battery life or a problem? why? (provide some technical arguments) __

I think it will be a saving but I am also scared about "other things" detecting and enabling advanced chipset power management features only when some services are started.. and fear these "services" may be off in text-only mode?