I guess this answers the question if you really need to fully deplete the battery to clear this message or not.
I really couldn't recall for certain that I ran mine down until the R30 shutoff or just somewhere above that point.
Hopefully this will work for you. When it's done this time, look at the battery info screen in the menu's and see how many cycles it shows. Just curious on that one knowing you charge a lot with USB.
Good Luck.
Thanks - I checked the battery information before running it down the first time. It greatly under-reported the number of times I've recharged the battery. I think I probably did not run the charge down enough for the radio to register that it went through a cycle. From now on, I will run it down to a lower level before re-charging. I will resume running the battery charge level down tomorrow night after work. I'll report on the results, when I finally re-charge turn it on again.