Current limit when using it without battery installed

Has anyone used Surface Pro 4 without battery installed? I've got i5 model and the clock speed won't go up above 1.7Ghz when used without the battery installed. I tried using the device both with battery completely removed and with only battery control board installed and in neither cases seems to go above base clock..

I could install new battery but it's really easy for them to become "spicy pillow" and I've already replaced them once. Don't want to go into hustle of replacing them again.