When I played with win10 on a surface it had two different power settings menus, one that seemed like a new menu (may be in 8 as well, idk, I avoid 8), and the standard one like in 7.
The one I'm used to is this:
It had that AND anther one.
Plus idk if you have an intel management software for the built in card but it may have different settings.
At the very least you should see about installing windows 10 drivers (assuming you did an "upgrade."
Yes it's odd, go ahead and change the plan to "high performance" on battery. When it crashes on that it does an instance "pol.exe has stopped working" yes?
I thought it may have two cards in that when on battery it's switching to the other, which would make sense as to why it does that, but I'm just outright curious now.