Legion Go S, safe to play with charger plugged in?

I recently got the Legion Go S, it's great. Currently playing LA Noire on it. With no charger plugged, I get about 1hr 30mins.

Now, is it safe to play with the charger plugged in for long hours? I noticed the battery would jump between 99% and full and obviously "battery remaining" would all over the place jumping between 100 hrs to 400 hrs.

My only concern is that I am not able to find a battery charge limit and wondering whether there is bypass charging already in play or do I need to do something in the settings?