Over the weekend, you might have read the solution to my dilemma over my Surface Power Cover not charging. If not, and you're having a similar issue, check out Surface Power Cover Does Not Charge When the Device is Off to get a better understanding about the essentials of ensuring the Power Cover is able to take a charge.
Going through my own troubleshooting steps, I also learned a bit more about how the Surface splits charging time between the onboard battery and the Power Cover, and thought I'd share as I'm sure it will be valuable to know for other owners of the keyboard/battery add-on.
Here's how the charging sequence shakes out:
- The Power Cover will NOT start charging until the Surface's internal battery has reached 80%.
- Once the internal battery reaches 80%, the Surface hands over the charging task to the Power Cover.
- Once the Power Cover reaches its own 80% charge, it switches charging back over to the internal battery to finish up.
- Once the internal battery reaches 100%, the Power Cover starts charging again until it also reaches 100%.
Obviously, how quickly either charges depends on whether or not the Surface is in use during charging, and of course, as you now know the Power Cover will not charge if the device is turned off.