You will get different answers from different people. The newer Lithium batteries are not well understood by all. Unlike the preceding batteries each individual cell is charge separately and balanced and do not hold a memory. The charging system is quite a bit more complex and as noted by our esteemed moderator its automatic and will regulate the charge dropping it by 5% or so before initiating a charge cycle. To see plugged in and not charging is intended operation. If you have 0 percent then either your charging circuit is cooked or more likely you have two open cells and need to replace the battery. Unfortunately there seems to be a QC issue with batteries these days as they are all made in one country that doesn't care about QC. I just had an incident where a brand new bank of 36 VRLA batteries went into thermal runaway, not pretty.
Thanks for the thought in providing the link. Its very old information from 2010 and does not cover the batteries in the newer machines that uses the lithium Polymer type batteries. Even so I would have argued many points with the author in 2010 when it was written. It does have some useful general information.
