Thanks to this thread I learned about the Aukey PB-N37, 5000mAh, single cell 26650 powerbank. I like the fact that both endcaps can be screwed off. This way you can test the cell or even replace it if necessary. On the other hand I would not recommend it to those unfamiliar with li-ion safety, so it is more of an enthusiast’s powerbank.
I bought one online for €9,99 and it’s in fact very easily taken apart and desoldered:
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Cylinder and endcaps are aluminium and both caps screw off.
The whole package sits tight enough in the cylinder so it does not rattle, but it simply slides out to the electronics side (it’s a bit tighter when pulling out on the cell side).
The cell looks like a PLB INR26650-50A (the cell Liitokala uses for their 26650-50A) and my test showed a capacity of 5048mAh at 1.5A discharge rate on a Miboxer C2-4000. That’s a very good result.
The electronic has a very small current drain when the powerbank is unused. I soldered a 0.1Ohm shunt between cell and board and with a UNI-T UT61E measured a voltage drop of 0.00-0.01mV. This translates to <0.1mA.
The powerbank activates when an USB connector is inserted and deactivates when no current is drawn or when unplugged. There is no switch. It has an LED on the PCB to indicate charging (green) or roughly the charge state (red, green, blue).
The powerbank charges the cell to 4.19V resting, it discharges down to 2.89V and then turnes itself off.
I charged several phones and electronic toys with the powerbank, as well as using it to power a Lii-202 charger with a 2A current draw.
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Electronics and cell:
