Clamshell mode powering 2 external monitors now with 2nd swollen battery

Atlanta Yankee wrote:

Working from home for years now, I've primarily had my laptop (Late 2013 model) in clamshell mode in a vertical holder made for this exact purpose. Connected to the MacBook Pro are two external monitors. I'm about to have my second swollen battery replaced but according to the thread I found below, clamshell mode should protect my battery from overcharging since I can't unplug it as this is required to power the external monitors. Am I unfortunate to get junk batteries or is the post I'm referencing below incorrect information? FWIW, I'm running Mojave 10.14.6 for specific reasons and not the latest OS.

https://discussions.apple.com/thread/251672590

While I'm aware that this laptop is going on 8 years old, should I have needed to replace two batteries already?? Any insight would be greatly appreciated.

Batteries can fail at anytime.

I do not see this related to clamshell mode , plugged in 24/7, or two external monitors.

Learn how to get your Mac fixed and how much it will cost. https://support.apple.com/mac/repair/service

Get your Mac ready for service - Apple Support https://support.apple.com/en-us/HT209095