This is a “Skylanders” theme portable burger speaker. I got this from local BigW for $10.
This speaker has built in rechargeable battery, with output rating of 2W rms and 3.5mm audio jack.
A similar speaker from BigW can be found here.
The Lithium battery is PL402030 – 180 mAh. The battery cell includes protection circuitry to protect from overcharging and overdischarging.
The audio amplifier semiconductor is NS8002 from NSIWAY. The datasheet can be found here (unfortunately it is in Chinese). The amplifier is rated 3W and can take input voltage of 2.2V – 5.5V.
It appears that there is no proper battery charging circuitry on this PCB assembly. The pad on the PCB is left unmounted. The battery is connected directly from the +5V input voltage through a drop resistor and a diode. Is this how they can sell for $10? By excluding proper charging circuitry from the PCB assembly? Hmm, not happy.