UV-5R V2+ battery level and low battery behavior

[pdxesto]

My UV-5R V2+ displays battery voltage when the '0' key is pressed and held for a few seconds. What battery voltage constitutes 'low battery' level? How does the battery voltage readout relate to the battery level icon/indicator, wrt to 'tic marks' in the battery icon? At what voltage is the battery icon empty?

Hope someone is listening...

Thanks!

[pdxesto]

Also, can someone tell me what the voltage is on a fully charged li ion battery for the UV-5R V2+? I think my battery or charger is flakey.