Welcome 
I have a thinkpad X1 carbon (gen 5) and the battery lasts 2-3 hours max with average 10 VMs running (with archlinux it used to last 13h). So Qubes is pretty demanding in terms of battery life from what I’ve experienced.
In my case the only things that significantly degrade more the lifetime is watching videos (the fan blasts) and for some reason when I use the Tor browser (but only sometimes).