Blackube AA 2550mWh USB (Gray)

Official specifications:
  • Voltage: 1.5V
  • Energy: 2550mWh
  • Output current: 4000mA
  • Charging current: 5V/350mA
  • Charging time: about 2h
  • Cell type: Li-polymer
  • Life time: 1000-3000 cycles
  • Weight: 19g

This is a USB charged 1.5V battery, there is a LiIon cell, a buck converter and a charge circuit inside.

Behind the hole is a red led, it shows red while charging and turn off when finished.

Included with the batteries is a 4 way USB charging cable, i.e. any 2A USB charger can charge four batteries simultaneous.

The capacity depends a bit on the load current, but output voltage is stable.

At low current the capacity is also lower, because the internal regulation also needs some current. This cannot really be seen from my curves here, i.e. the internal current consumption is very low and the battery will last for many months before it has discharged itself.

The battery can deliver up to about 4A before the overload protection kicks in.

The electronic circuit makes the internal impedance look strange.

Output voltage do not change much when load is turned on or off.

It looks like the buck regulator runs at about 1.2MHz. The noise is less than 30mVpp, but I cannot measure lower with the current setup.


These batteries has less capacity than normal NiMH, but run at a higher voltage, making the energy about the same. This makes them ideal for most equipment that has trouble with NiMH batteries. They also weight considerable less than NiMH, this can be significant in some circumstances. There is one disadvantage: Battery meters do not work with them.
The USB charging makes it very easy to find a charger for them.

Notes and links

The batteries was supplied by Blackupe/ for review.

How is the test done and how to read the charts
Compare to other AA/AAA batteries: Alkaline/NiMH/Lithium