Blackcell Bu4 Usb Charger

BU4 is an intelligent charger, which combines convenience and fast charging into a single unit.


Charging times depend on each batteries current capacity, although the independent output (1A, 2A) and pulse charging circuit are compatible with any cylindrical Li-ion batteries (3.6/3.7v), Ni-MH and Ni-Cd batteries ranging in size between 10440 up to 21700. The BU4’s 3 LED display allows for clear viewing of the current charging status.


Input Voltage DC USB5V 2A
Output Voltage 1.42V+0.05V, 4.2V+0.05V
Output Current 500mA*4/1000mA*2/2000mA*1
Output USB 5V/1000mA
Charging Mode constant current and constant voltage
Constant voltage cutoff current <100mA
External power supply stand by current <15.0mA
Size 111mm*86mm*32mm
Weight 122.7g(Charger Only)
Compatible with IMR/Li-ion: 26650 22650 18650 18400 18350 17670 17500 18340 14500 10440 21700 20700 Ni-MH/Ni-Cd: AA, AAA, AAAA, C
Input type USB

USB Output

  • USB output load voltage: 4.90-5.30V
  • Output current: 1000mA
  • Floating current: <1mA
  • When load current is 1000mA, USB output voltage is 4.75-5.25V
  • Cutoff output protected voltage: 3.0±0.1V


  • Four, independent micro-controlled charging slots allow for simultaneous charging at 5V DC USB input.
  • Automatically distributed charging current (500mA*4/1000mA*2/2000mA*1), 2000mA for slot 4 only. 500mA is the default setting for charging Ni-MH and Ni-Cd batteries.
  • LED display charging status 30%, 70%, 100%.
  • Li-ion and Ni-MH Ni-Cd batteries are automatically detected.
  • 0V voltage Activation capabilities. Trickle charge activated when the battery voltage is between 1.65-1.85V.
  • Faulty batteries and battery reverse connected batteries are automatically detected.
  • Charging mode: constant current and voltage.
  • DC input, the power supply is 5V 2A (Micro plug).
  • Automatically detected USB 5V/1000mA output function.
  • Certified by CE, ROHS, and FCC.
  • When no batteries are installed, the three LEDs will flash and then turn off one by one when the charger is connected to a power source.
  • When a bad battery is installed, the three LEDs will flash at the same time.
  • During the charging process, the three LEDs light up one by one, and will all stay lit until charging is completed.


  • The product is for use specifically with Lithium, Ni-Cd and Ni-MH batteries only. Charging other batteries can potentially lead to an explosion, broken or leaking batteries, personal injury or property damage.
  • Incorrect use of the charger may lead to an electric shock.
  • The BU4 charger should only be used indoors or inside a vehicle. Under no circumstances should it be exposed to water, high humidity, and low or high ambient temperatures.
  • Do not disassemble or modify the charger.
  • Please use appropriate AC voltage 100-240V.
  • No BlackCell products are intended for use by anyone under the age of 18.
  • The safe operating temperatures are between 0°C-35°C 32°F-95°F.
  • Do not drop or rest heavy items on the unit.
  • If any problems arise with either the batteries or charger, unplug the power cord immediately.