I have two 5V 2A chargers. I want to get 5v 4A. Can I connect both in parallel like this?:


simulate this circuit – Schematic created using CircuitLab

Can I do it? Because in parallel connection voltage doesn't change, so 2A +2A = 4A

  • \$\begingroup\$ What chargers exactly? The theory on which you based your assumptions in the question has some simplifications and real world is quite a bit different from that, so the charger type is important. \$\endgroup\$ – AndrejaKo Apr 24 '15 at 16:22
  • 5
    \$\begingroup\$ Your question will get better responses if you use the normal rules of English grammar when writing it. For example, capitalize the first letter of each sentence and the word "I". Also, use the common accepted spelling of words, instead of writing as if you're sending an SMS to your buddy. \$\endgroup\$ – The Photon Apr 24 '15 at 16:28
  • \$\begingroup\$ @ThePhoton And removing the random "Text Element"s would help too... \$\endgroup\$ – Greg d'Eon Apr 24 '15 at 18:07

You may be able to parallel the chargers by adding what we call "ballast resistors" in series with each charger (before the parallel connection). This is assuming that the chargers are identical.

The problem is that even with identical chargers, the output voltage isn't exactly the same. The charger with the highest voltage wins and tries to supply all of the current. Because it can't, it goes into current limit. That forces the charger with the lower output voltage to try and take over the full load. But it can't.

Depending on the circuit design inside the chargers, any manner of weird things can happen. The output might oscillate, it might collapse either partially or completely - we don't know.

By adding a low-value resistor in series with each of the chargers, you allow a small amount of voltage drop. Now the chargers are better able to work together.

You usually don't need much of a voltage drop in the ballast resistors. I'd try for 100 mV and see what happens. 100 mV / 2A = 0.05 Ohms.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.