In an update FAQ, Microsoft explains that the battery levels in some Surface Pro 3s were being misreported to the operating system and firmware, meaning the tablets stopped charging well before they hit full capacity.

"Think of this like a fuel gauge in a car, where the car looks to the fuel gauge to determine how much to fill the tank," Microsoft says. "In this case, if the fuel gauge isn't working right, the car would also not be able to fill the tank -- even though the tank is fine."

After applying the update, the battery issues will self-correct over "the next several charge and discharge cycles," Microsoft says, and any tablets that weren't able to run on battery power will be able to do so.