USB battery box 3x18650 XD-168



This usb box does not have any name, but on the bottom it has the type number XD-168. I got it from ebay.
The specifications from one dealer:

• USB Output: charge mobile phone, MP3, MP4, tablets
• Micro Input: absorb energy from PC, laptop, wall charger, car charger
• 4 charging connectors: Apple 30-Pin / Mini / Micro / Nokia DC2.0
• 4 LED light reminds stock energy, each one light stands for 25% energy. Bright light means full, flashing light means not full, dark means none.
• One illuminate light, press power button 3 seconds continuous.
• When the mobile phone is charged full, power bank turns off automatically.
• Dimension: 100×60×23mm
• Weight: 70g
• Color: Black / White

How does it look



The box arrived in a envelope.




Included with it was a couple of connectors and a instruction sheet, but I did not get much out of that sheet (I believe that it is in Chinese).



On top of the box is a "on" button and on the bottom is a unlock slider for the cover. The on button is flashing green when the output is on.



All connections are on one end of the box: A led for flashlight use, the button must be held down a few seconds to turns this led on or off. A usb output connector and a micro usb input/charge connector and four blue leds to show the power status:

• 4 leds: min 4.10 volt
• 3 leds: min 3.91 volt
• 2 leds: min 3.61 volt
• 1 led: always

While the output is on the power status is flashing.



Sliding the unlock slider, and the cover can be lifted off.



The box has space for 3 18650 batteries, either button top or flat top, that can be up to 70 mm long.

There are no pictures of the electronic, the box is sealed.



Measurements

• Overload disconnects the battery at 1.6A
• Requires charger to reconnect battery
• Need a minimum load of about 450mA to turn on
• When on, it will not turn off, before the load is removed (even 1 mA is enough to keep it on).
• Flashlight is turned on/off with a long press on the button.
• In battery disconnected state the box uses no current from the battery.
• With battery connected but output disabled the box uses about 0.2mA (This is more than 5 years with a full load of 3100mAh batteries).
• When a charger is connected, the output will be off.
• Output is coded as Apple 1A

A load sweep shows that it can deliver up to 1.6A, before the output turns off. It did disconnect the batteries, i.e. before it worked again I needed to connect it to a charger.



On the bottom of the box it says that it can supply 1.5A and the load sweep shows 1.6A, but doing a test at 1.43A does not work for more than 30 minutes.



Reducing the load to 1.25A work better, but again the box has problems after some time.



Using a 1A load (As specified on the website) works much better. The box has a efficiency between 80% and 90% and keeps a very stable output. But it does not run the battery dry, it stops at about 3.3 volt, this is about 500mAh early for a 3400mAh cell.



With a 0.5A load the box can supply current for nearly 11 hours.







The 2600mAh battery does very well, because it has higher voltage than 3100/3400mAh batteries, this allows the box to better utilize the energy from this battery.



The box has a very low noise, this trace is from the 1.25A load (9.3mV).
Note: To measure the noise I did use a more sensitive range.



Reducing the load, does reduce the noise slightly (7.9mV).



The box need a high load to turn on, but when on it will first turn off when the load is very low for 50 seconds.



The charging is not CC/CV but just as good, except for longer charge time. The box needs 12 hours to fully charge a set of 3100mAh batteries (Note: These batteries were fully discharged, if they had only been discharge in the box, it would have been faster).





The time to charger 3100/3400mAh batteries is nearly the same.



The 2600 is slightly faster.



Conclusion

This box is good up to about 1A, with very low noise in the output. Using a mini usb input for charging does also make it compatible with phone chargers, without carrying any extra cables. The build in light makes it possible to connect equipment in darkness.
I have only a few complains about this box, but this does also mean that I am not going to use the box when traveling: Why does it not have a reconnect button. If I replace the batteries or overload the box, I cannot use it before I connect it to another usb charger. I do also wonder if the high turn on current will give problems with some equipment.



Notes

Read more about how I test USB power supplies and chargers