I’ve got a JKK03.
Charging is via the µC up to 2 amps. Power bank LEDs will automatically turn on. I’ve never left it charging more than about 1 hour and the red LEDs remained ON. Pulled the batteries out and measured 4.02 V. Charged again for some 30 minutes and re checked at 4.20 Volts. Don’t know if turns off when fully terminated or pulses a trickle charge. Haven’t tried the 5 Volt barrel connector (also for charging). The Outputs are the regular USBs. Haven’t tried the capacity though (1 or 2 amps).
Double click for indicating LEDs OFF:
If I press On & OFF within 2 seconds will turn off.
Made a mini review but didn’t test the power bank.