I like the little HP Stream 11 laptop but Ubuntu is a bit slow on it so I've recently installed Lubuntu Linux. Based on Ubuntu but with a lighter weight desktop and windowing environment it runs well and does not use the 2GB of RAM available in this machine.
Even with the Chromium browser running there is free memory available.
To find out more detail about where your battery power is going, there's a utility that can be installed with apt, called powertop.
Amazing to see an Intel laptop consuming 3.55W.
There are a bunch of tunable settings that can be adjusted in Linux to get better battery life, mainly turning on some power management settings, I've turned on each of these and so far so good.
While Lubuntu is fine, I do miss a few things from full Ubuntu such as the ability to search for an app to run it, also the window edges are very narrow and rather hard to grab with the mouse.
I've noticed that some operations, such as 'apt update' hang for 120 seconds before starting. At first I thought this was a DNS issue but it turns out that disabling ipv6 fixes this for me. (Obviously, I would prefer to use ipv6 but perhaps my ISP or home network isn't quite up to it).
All in all, worth a try on a low end laptop.