USB battery box Eachine Mini Y5

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The box has an unspecified number of batteries, a usb outputs and a small flashlight.
The specifications are:
I got the box from Eachine



How does it look

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The power bank is delivered in brown cardboard box with a wrapper.

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

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On one of the sides there is the button and display button, it will always turn the display on with a percent remaining value.
When the box is on a click on the button will turn the flashlight led on or off.

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Another side has the micro usb input connector and a led for flashlight usage.

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On the third side is the usb output connector.

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The bottom of the box has the specifications on it.



A look inside

The box did not work as expected and I decided to break it open and take a look. The scratch on the battery is my doing.

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The box uses two 3000mAh Samsung batteries, this looks very good.

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Here is the problem, one the of battery connections was not welded, i.e. the box uses only one battery.



Measurements


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The first test is a load sweep to get an idea about the performance. The output can deliver 2A, but it does not look like there is an overload protection.

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The output looks very fine at 0.5A with about 1800mAh capacity, this is about half the expected capacity. See the look inside for an explanation.

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With a 2A load the box is fighting hard to keep the voltage up and it succeeds

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At 0.5A load the noise is low with 12mV rms and 140mVpp.

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At 2A the noise is increased to 38mV rms and 380mVpp

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The charge curve looks like a classic CC/CV charge curve and the batteries are charged with around 2700mAh.
It takes about 2 hours to fully charge the power bank and requires a usb power supply that can deliver 1.3A. If both batteries had been connected I would expect a charge time between 4 and 5 hours.

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Adding some series resistance, equivalent to a long cable or a weak charger reduces the charge rate and still does a nice CC/CV charge.



Conclusion

The box works fairly well, except for the production fault with the missing battery connection I will call it a good power bank.



Notes

The power bank was supplied by Eachine for review.

Read more about how I test USB power supplies and chargers