This doesn't match my experience. My previous three laptops (two AMD Lenovo Thinkpads, one Intel Sony VAIO) had essentially the same battery life running Linux as running Windows.
I have an AMD thinkpad and get maybe 1/4 the battery life on Linux as I do when I boot inti Windows, did you have to do any tweaking to achieve that?
You're lucky, my thinkpad x13 gen 2 AMD gets 5 hours on modern Fedora vs. 9 or 10 on Windows.