On most laptops I find using a battery for any kind of heavy work a non-starter anyway. I might send an email or take a call on battery but I wouldn’t even launch a heavy IDE. Without aggressive power saving (I.e CPU sits under 1GHz even att full load meaning less than half the performance) then battery is often less than 30 minutes. I should add that this is for scorching hot “desktop replacement” (45W) laptops. But I also wouldn’t want to compromise on perf while plugged in, in order to get more battery time.