I have a system that uses Arduino and some modules. The system needs 5v dc power with 3A current at maximum(The system needs 3A current for some seconds every 5 minutes and after that the current will get back to 300-400mA) and on the other side i have a 5v dc charger with 400-500 mA current. So my problem is lack of amperage and i can't run correctly Arduino with 5v dc charger. For solving this problem i want to use a Lipo battery to connect to Arduino but the battery will ran out and i can't get energy from battery so i want to connect the battery to my charger while the Arduino uses the battery, How can i do that? Is there any module to do this work? Can i use TP4056 with protection version to do this work?(Note: I can't change charger)

1 Answer 1


You really shouldn't charge a lithium battery whilst discharging it. The charger may either never know that it has finished charging and overcharge it, or shut off early and never charge it up properly at all.

Instead you should arrange that your MCU is powered directly from the PSU so that it always has stable power, and feed that same power into a normal charger via some form of electronic switch so it can be turned on and off. The output of the battery can then be fed through another switch into your heavy load.

When it comes time for your load to be activated you switch off the power from the charger and switch on the connection from the battery to the load.

What you use to do the switching is entirely up to you - whether you choose P-channel MOSFETs or relays entirely depends on your situation.

Here's a block diagram to better illustrate it to you:


simulate this circuit – Schematic created using CircuitLab

  • If i can't charge while discharging so what is load-sharing battery charger circuit(like this learn.adafruit.com/…)? Aug 22, 2019 at 22:11
  • That is one which will pass the incoming power across to the load when charging (so the incoming power goes to both charging the battery and powering the load) and then switches to the battery to power the load when the incoming power is removed.
    – Majenko
    Aug 22, 2019 at 22:15
  • Can i use this circuit (amazon.in/CentIoT-TP4056-lithium-Charging-Protection/dp/…)? Aug 22, 2019 at 22:15
  • That circuit is the single box in the diagram above called "Charger". It is up to you to provide the rest of the circuit.
    – Majenko
    Aug 22, 2019 at 22:16
  • I think this circuit has battery output and you can use while charging you can see in this video (youtube.com/watch?v=Qw4psECqpwI). Aug 22, 2019 at 22:29

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