I believe this was posted here before - some battery tips to prolong their life:
As for the 80% for storage I could not find the exact link, but i had read that for storing it long term, it’s best to start at a 80 or 85% and check the voltage and if it drops below 50% charge it back up to 80 again.
Where i work - it’s in a high tech field where we have 35 technicians flying around NA that we hired from school or from other high tech electronics industries. One of these guys explained to me that a Lithium battery works like a mechanical spring. The spring fully compressed is the equivalent of a 100% charge. By taking it to that 100% charge all the time, just like a mechanical spring it starts to lose its original ability to spring back to 100%. This is demonstrated in the “Battery University” Link I pasted above. You get more cycles out of your batteries if your usual charge/discharge stays at a lower range. If you know you are going for an unusually long ride, then by all means do that 100% charge. But generally I try to follow the recommendations in the link now and charge to a lower percentage or voltage. I judge it and use a simple lamp vacation timer to to turn off the charger so i don’t forget.