I have used some for time Barkan PB22B 2200mah Portable Charger Black to charge my smart Samsung S4 mini phone. I had some issues first that the charging was not reliable with my phone (worked well with some other devices). I decided to look what was wrong with USB Power Current Voltage Tester, and with it plugged between the portable charger and smart phone everything works fine without problems. So now I charge my phone on the go with Barkan PB22B 2200mah Portable Charger Black andUSB Power Current Voltage Tester.
One day the case felt a little bit loose, I decided to look what’s is inside.
Take a closer look at the electronics built around 134HOP (or 134H0P) chip (for which I could not find data sheet with quick Google search):
Here is a close look at the Li-ion battery on the device.
From the data on battery, the battery pack can hold 2200 mAh charge at 3.7V. When I charge phone with it, I will get less than 2200 mAh of 5V power, because the voltage needs to be boosted from 3.7V to 5V with swith mode power supply. With ideal power supply I would get around 1600 mAh at 5V USB output, with real life power supply circuit with some losses I get less than (expect to loose 10-20% of power on the power conversion).
This is quite typical situation on USB portable chargers. They are marketed with battery manufacturer promised mAh rating on the battery itself, not the actual mAh you will get from the device when you charge your phone with it.