If you have a Surface Pro 3, you probably received a firmware update on or around 8/292016. This firmware update is a fix for Simplo batteries only. Most people have reported their SP3’s with Simplo batteries now show reasonable capacity (but there are customers reporting bricks).
A trend is appearing in the Microsoft Community Forums (Answers) that suggests that something in the firmware to fix Simplo has had a bad impact on Surface Pro 3’s equipped with LGC batteries. This thread has some folks posting about this http://answers.microsoft.com/en-us/surface/forum/surfpro3-surfhardware/surface-pro-3-with-lgc-lgc-battery-degradation/13d03fbe-1edd-489f-bd0a-2c07ff615128?msgId=25830051-4e6d-4a5d-b194-2e78168e6534 (and there are a couple of others).
If you have a Surface Pro 3, you should open an administrative cmd prompt and type
powercfg /battery report
Save the file and if it looks like the samples below, post in the above thread. As you can see, these folks are stuck on a fixed, less than 100% capacity. This condition was not present prior to the 8/29 firmware update. You can also let me know on Twitter, @barbbowman if you are impacted.