MH-CD42 DC 5V 2.1A Mobile Power DIY Board 4.2V Charge/Discharge(boost)/battery protection/indicator module for lithium

MH-CD42 is lithium battery charger 2.1A and discharger(3.5A) unit with battery level indicator LEDs, ON/OFF switch and

MH-CD42 is a Lithium Battery Charger that can be used as Uninterrupted Power Supply (UPS) . This module has input, charge and output ports. On the module we also have four charge level indicator which Light Emitting Diodes (LED). We also have an output enable LOW trigger line to turn ON the output.

The module has a power ON/OFF switch.

Product Features

Charging voltage: DC 4.5V-5.5V (recommended DC 5V)

Charging current : 0-2.1A

Charging quiescent current: 100uA

Full voltage: 4.2V+-1%.

Discharge current: 0-3.5A;

Discharge quiescent current: 50uA

Discharge efficiency: 96% maximum

Output voltage: 5V

Output current: 0-2.1A;

Ambient temperature: -20° to +85°

Module with lithium battery protection function (for lithium battery without

protection, with protection board)


Overcurrent protection (OCP)

Overvoltage protection (OVP)

Short circuit protection (SCP)

Over temperature protection (OTP)

Charge and discharge power level 4 interval indication

Pin definition

  1. Charge pin 4.5V to 5.5V (recommended 5V) to be connected to your power supply or USB
  2. GND or negative pin for charge pin above
  3. GND pin to be connected negative pin of your Lithium battery
  4. BAT pin to be connected to positive pin of Lithium battery
  5. GND pin for output to be connected to your load negative pin
  6. VOUT pin for positive pin of your load
  7. ENABLE trigger port.
Out is Pin 1.

Charging LEDs levels

Level (charger C)LED1LED2LED3LED4
Charging Levels meaning

Discharging LED levels

Level (charger C)LED1LED2LED3LED4
Charging Levels meaning

Turning ON/OFF using Trigger Signal

When the load it connected for the first time, the output is turned ON automatically. In discharge mode the PIN 7 is not functioning. When pressed once, the output is turned ON and stays ON. to turn the output OFF, press or set it to low twice.

If the load draws less then 50mA, then the output will be turned OFF for 30 seconds. If the output current is greater than 50mA, then the output will stay ON continuously.

If the output voltage is between 4.7V to 5V, the the output can be used while charging.

Charging and Discharge diagrams

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