Battery module in CUBE is special design due to it can’t be replaced.
Yes, over charge and over discharge are harmful to Li-ion battery.
But CUBE uses precision charge and protect ICs to protect its battery.
The UAS TI (Texas Instrument Inc.) IC BQ24171/24133 and 0.1% precision resistors are adopted by Sugr.
So, 8.65V±0.7% precision charging voltage is achieved.
To prevent battery from over discharge, Japanese precision Li-ion battery protect IC is adopted, it’s made by SEIKO.
SEIKO IC can guarantee the voltage of battery stay in range 5V~8.7V.
In fact 4V~8.8V voltage range is safe to CUBE battery.
Thus, the battery is extremely safe and you never need to concern it.
You can plug CUBE in to a power source full time and the battery capacity will NOT be affected.
Regarding to sleep function, so far, this function is pseudo, it is just a MUTE state.
The software engineers are working on DLNA, Spotify connect, Qplay etc.
True sleep function will be realized in future.