
I was given an S-A-A-2 unit. Specific documentation for this particular unit is basically non-existant.
I used the supplied micro-USB to USB charging cable with my cellphone's charger. Three very bright red LEDs on the back of the metal case lit up and a fourth was blinking. Shortly thereafter that fourth LED list up constantly. I presume these tell me the state of charge of the battery. Since these LEDs are on the back of the unit, I won't ever see them unless I pick the unit up and turn it over or get a reflection off the table.
How long should I charge the device?
Can it be overcharged?
Will it hurt to leave it plugged in and charging for more than 24 hours?
Do these LEDs really tell me anything useful, like a rough idea of the amount of run-time remaining?
If a USB cable is plugged in and the unit is turned on, does the battery charge while it's being used?