I had the same problems with my laptops (Asus S540CM and Asus X556UQ which is fairly new). Sometimes it would indicate the "UNKNOWN BATTERY" or "NO BATTERY IS DETECTED". I have tried the uninstall the battery driver fix but it does not work. I have found what worked for me in a hard way. (maybe this could help others)
The Asus S540CM has an external battery, removing the battery and putting it back in did not work for me so i bought a new one as I thought the battery is dead considering it is an old laptop. When I put the new battery, it "fixed" the problem, however, after two weeks of using the new battery, the problem of "UNKNOWN BATTERY" or "NO BATTERY IS DETECTED" recurred. First i thought the problem was with windows. Again, I tried the uninstall the battery driver fix, again, nothing was solved. So I tried to investigate further to this problem, upon closer look on the terminal of the battery, it appears that it was dirty (molds - maybe because I live in a tropical country) so I cleaned it with denatured alcohol and let it dry good. NO MORE ERROR. This worked for me and I would not guaranty that it would always work.
The Asus X556UQ which has an internal battery is another story. It began when I dropped my laptop (first i thought it was because of the recent windows update) so I restored my laptop to the last update. It did not fix the problem. So i pried open my laptop and removed the battery and put it back in. AAAAND it worked. Problem fix. For those who have laptops with an internal battery avoid dropping it, especially those laptops made out of mostly plastic. Hope this could solve your problem.