Hi
@Daneflyer ,
Thanks for your kind words and I hope the video was useful.
You can absolutely charge above 80 and go below 30. This won't harm the battery very much EXCEPT that you should not let them stay at very low or very high voltages for long periods of time. Even if you do once in a while, that is fine but regularly sitting at voltages above 90% will accelerate some of the parasitic reactions.
So, I charge my batteries to 85 or 90% and when I do need the extra range, I just charge to 100% but then I use it immediately.
For your question, I would charge to 90% and then safely take it down to 10%.