Thanks man.
I am keeping one of the 2017 machines plugged-in about 100% of the time. It's a very convenient setup and my external monitors forget where they were if I unplug.
Is there a way to find out if my battery is likely to swell?
And would it be enough if I disconnect, say, once a week and discharge to 50%?
When you are plugged in, you can use a tool like Charge Limiter to keep the battery charge at 50% all the time.
When you want to plan to use the battery, you can set the charge limit back to 100% and it will charge fully.