Beoplay E8 charging

I know that batteries have a certain amount of charging cells and I heard if I keep my cell phone on the charger most of the time even when fully charged it will eventually lower the life expectancy of the battery. Is this the same situation with the Beoplay E8 earbuds and case? I keep the case plugged into an outlet and leave the earbuds in the case approximately 20 hours a day. I appreciate your responses.  

It’s my understanding that leaving the headphones in the case long term (and even leaving the case plugged into the mains) won’t cause any problems because it’ll stop charging once full and won’t start charging again until you pull them out and put them back in. However, if you constantly plug everything in to the mains right after using the headphones that can cause the battery to degrade over time but I’m not sure it’ll cause a hugely noticeable difference over the average lifetime of the earphones (and if it does, they’ll probably just fix it all under warranty anyway - despite warranties not usually including “consumables” like batteries, both Apple and Toshiba have replaced non-user replaceable batteries for me in the past for laptops and phones so I’m sure B&O is the same given the brand and the price of the earphones).