How long can the charging case be unplugged before it will not be able to charge back up ?
I had a few spare Sleepbuds II that I was not using. After about 6-7 months or so I finally unboxed them. Upon plugging in the charging case for the 1st time, none of the cases would charge up (tried for over 24 hrs) - all completely dead. I called customer support and had them all replaced. I was told the case battery was most likely depleted to a point were it would not charge.
My question is, about how long can we leave the charging case unplugged without the battery being depleted to a point where it will not charge back up ? I have spare SBII that I will not be using and would rather not leave the case plugged in all of the time.