Lenovo thinkpad laptop shutting down on its own

I have a very weird problem with my lenovo thinkpad E540. Sometimes when I use the laptop it shows a message that the battery is very low and the laptop shuts down on its own. Perhaps i should say sleeps itself. Because when I turn it on again it boots fast and the program data is saved. The problem occurs roughly every 2-3 hours of use. Now the weird thing is that it occurs ONLY when the laptop is plugged in and charging. It has never occured when I use the laptop on battery only. I have also tried using the laptop, plugged with the battery removed and the problem did not occur. I should also

Question by Teodor Dyakov on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.