Panasonic QE-QL103 USB Power Bank

[dexters_lab]

I picked up two types of USB power bank when i was in Japan last year, the QE-QL103 (2900mah 1A) and a QE-PL203 (5800mah 1.5A & Qi Charging), the other day i was curious enough to break open the smaller of the two as i wanted to see how these branded, Japanese made power banks compare to the Chinese stuff you find on ebay.

the QE-QL103 costs about £12 from Yodobashi, so is not an expensive item considering it will have a good quality Panasonic 18650 cell inside.
http://www.yodobashi.com/%E3%83%91%E3%83%8A%E3%82%BD%E3%83%8B%E3%83%83%E3%82%AF-PANASONIC-QE-QL103-K-USB%E3%83%A2%E3%83%90%E3%82%A4%E3%83%AB%E9%9B%BB%E6%BA%90-2900mAh-USB%E5%87%BA%E5%8A%9B%EF%BC%9A1%E3%83%9D%E3%83%BC%E3%83%88-%E6%9C%80%E5%A4%A7%EF%BC%9A1A/pd/100000001001763317/

There is micro USB for charging and a standard USB for output to devices, handily it also includes a removable micro USB adaptor that can aid charging and connecting to your micro USB devices.

It was a bit of a struggle to open, i had thought it might have been ultrasonically welded but it actually has a screw and clips.

I was surprised by the complexity of the controller board inside, containing an Atmel XMega16D4 http://www.atmel.com/devices/atxmega16d4.aspx?tab=overview

The battery and board are soldered together looping through a plastic carrier so i can only get pics of one side of the board, i did consider de-soldering the batter to see the other side but i wondered if it might not power back up when reconnected (i use this charger every day!). The battery also has a temperature sensor glued to it.

One thing i did do was measure the battery voltage. It turns off at about 2.6v and charges upto 4.3v so they are really pushing the max out of the cell. One thing i did notice is it seems to not draw power out of the cell all the time, when powered on and supplying power to a USB device i saw the battery voltage dropping in steps so looks like they are drawing power from the cell in pulses.

If people are interested i could bridge the battery terminals so i can remove the plastic carrier without disconnecting the battery and get a view of the other side of the board and do some more in depth poking around?