Using external monitor leads to an insane battery drain.

When I plug in an external monitor the system decides to turn on the discrete graphics and it just drains all the battery in a blink of an eye. It doesn't seem to be an issue with 13-inch model.

How can I make the system not to switch to the discrete GPU in order to save battery? I'm pretty sure that the integrated GPU can easily cope with just a simple HD monitor.

I haven't found any software that allows to do so.

I attach some photos of battery consumption levels, you can see an astonishing difference for yourself.

I cannot accept my LAPTOP running out of battery 5 TIMES faster than normal JUST because of an external monitor.

What can we do with it?

Without an external HD monitor

With an external HD monitor (discrete GPU on):

Raised issue: 101117450687