Do we have to charge less than 100% for battery efficiency?

@The techie 279  It's not a myth.  It's a well known fact of li-ion batteries.  This is why Tesla vehicles default to charging only up to 80% and will only charge to 100% when you specifically select a "Max Range charge", which you have to choose each time you want it; you can't make it the default.  For even better efficiency, you can set a minimum charge level of 50%.  In that setup, when the battery reaches 80%, the system will NOT keep it topped up even if you keep it connected to power.  Instead, the battery will be allowed to "self-discharge" down to 50%, which might take several days if you never actually use it on battery power, and only after it drops to 50% will the system charge it back up to 80%.  The reason this helps is that in this setup, the battery spends most of its time completely idle, i.e. not being charged, or being kept topped up, or actively drained.  The catch of course is that if you ever have to disconnect your laptop from power unexpectedly, you might only have a 50% battery charge.  When it comes to batteries, you can either optimize for everyday convenience (maximum battery charge ready as often as possible) or long-term lifespan.