Considering the laptop age is relatively young, the chance of battery degradation is very slim, especially if you're quite knowledgeable on how to handle electronics. Understand that Li-ion battery does not typically like to sit around maximum capacity for long time. This type of battery is also subject to overcharging which may cause permanent damage. It is because of this that modern devices are equipped with software that will regulate the charging as to not overcharge it or let it sit at exactly 100% for long time. By now, you probably have heard about trickle charging method. Once your battery reach 100%, it will draw power from the AC adapter and let the battery goes down bit by bit. I am not sure if there's a small portion of energy drawn from the battery, but the capacity will slowly go down. Once it hits a certain level, typically 95%, it will start to slowly charge again until 100%. What's most likely to happen is that when you shut down the laptop, it sits at around 95% or 96%. When you let it sit overnight for hours, it may lose 1% to 2% of battery capacity. All in all, try downloading HWMonitor application. It's free, and it can display all the sensors on your computer including thermal sensors, clock speeds, and battery capacity. Look how much wear it has. For a relatively new laptop, you should be looking at around 5% to 10% wear depending on how heavy you use it.