USB battery box EE Power Bar

This power bank is free to use in UK if you are a customer at EE, Orange or T-Mobile. It is possible to swap the power bank in any EE shop to a fully charged one.

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The specifications are:



How does it look

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The power bank is delivered in a yellow/gray cardboard tube.

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It contains the power bank, a usb cable and a instruction sheet.

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There is two connectors, a micro usb for charging the bank and a large usb for power output. The two connectors are very close, it is only possible to use one at a time.
The led is for flashlight usage.

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The ones marked E1-06 has been recalled, because some of them has burned.

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One the side of the box is 4 leds to show power level and a button.
Pressing the button will show the power level and turn on the output (Usual the output will turn on automatic when loaded).



Measurements


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The first test is a load sweep to get an idea about the performance. The power bank can easily deliver the rated 1A current, but there is no overload protection in it.

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The 10 ohm load is about 0.5A. The box delivers 1600mAh as expected and the voltage is nice stable at about 5 volt.
Note: Specifications always list battery capacity, output capacity will about 60% compared to that, due to the voltage difference between battery (3.7 volt) and output.

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With the load increased to 1A the box has some problems keeping the voltage up when the battery is nearly empty. The voltage stays within the limits. The higher load has also reduced the capacity a bit (as expected).

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Looking on the output with an oscilloscope show little noise, it has 12mV rms noise and 80mVpp noise at 1A.

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At 0.5A the noise is down to 7mV rms and 50mVpp.

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The specifications says the box need 1A when charging, this looks about correct. The cell need about 2600mAh to be filled.


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Adding some series resistance, equivalent to a long cable or a weak charger do not reduce the charge rate.



Tear down

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I could not break it open, but had to cut it.

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The battery is from Cham Battery Technology a Chinese manufacturer.

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This side of the circuit board contains all 5 leds, the charger chip (U2) and usb input connector.
The two chips (U4, U5) is probably handling some battery safety.

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The other side of the circuit board contains the controller (U1), the boost converter (U3, L1, D1) that converts from battery voltage to USB voltage and the output usb connector.

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Conclusion

Mostly this battery bank look well designed with good over discharge safety, but the missing overload safety can give problems if the box is used with a defect cable or phone (I wonder if you can get a damaged cable swapped).
The capacity is not very large for usage with a modern smartphone, but the possibility to swap it for a charged one in the nearest EE shop do help (if there is an open shop in the area). The swapping means you might get one with a well-used battery, i.e. less capacity!
Using a Chinese cell in the device is interesting. The quality on Chinese product varies from very god to very bad and it can sometimes be difficult to know what you get and it is rather important with LiIon batteries to get a good quality. I supposed EE or their supplier has verified that they get good batteries.

It is a fairly good power bank and the possibility to swap is interesting. I expect this will be very useful to many people, but it is no competition to a 4 cell power bank that you remember to keep charged.



Notes

The power bank was supplied by a reader for a review.

The first batch of these was 2 million unit and they was "sold" in no time. Many millions more are on the way (EE has about 25 million customers).

Read more about how I test USB power supplies and chargers