I've been working on a Surface Pro 3 battery issue for several days now. I've read many forums and tried so many recommendations, nothing works. My SP3 battery icon show: 1) plugged in 2) battery at 255%, 3) if the power cord is removed the device crashes.
I ran across your website during my latest research. I was able to follow all of your steps to download the CMBATT.SYS file and copy to each of the folders you directed on your webpage.
I rebooted my SP3, and now I see no battery / power icon. The device manager is showing your CMBATT.sys file, but it is telling me:
Windows cannot verify the digital signature for the drivers required for this device. A recent hardware or software change might have installed a file that is signed incorrectly or damaged, or that might be malicious software from an unknown source. (Code 52)
Great, yes MS is correct. How to override this MS error and allow your CMBATT.sys files to be properly recognized after my installation?
Reply: According to experience, I feel that your problem does not have much to do with the CMBATT.sys file. It is very likely that your battery is aging and not working properly.
You try the following methods:
1. In the off state, unplug the battery, then press and hold the power button for 30 seconds to discharge the static electricity, and finally plug the battery to boot.
2. If the system is win10, and the 1903 patch has been updated recently, please restore to the previous state, because this patch may incorrectly determine the battery capacity. You may also wait for the next update, and it will solve the problem.
3. Disassemble the battery, check whether the battery is inflated, or whether the appearance has obvious changes. If there is, the battery is damaged. In this case, replace the battery in time, otherwise there will be an explosion possibility.
4. Check the contact points between the battery and the notebook for rust or poor contact, as the poor contact may affect the notebook's normal use of the battery.
After the battery is used for a long time, the capacity will gradually drop. At the end, the battery will not be used. This is a normal phenomenon. Generally speaking, the battery of the notebook can only be used for 3 to 4 years.