Help with choosing a relay.

Hi. I'm trying to do a project that involves switching an external device that has its own power source. The device runs on 5V and 3A. Which relay should I use?

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AC or DC , resistive or inductive load ?

As mentioned look at relay specifications for the answers - the cheap hobby Chinese modules give little information , so start looking at RS components or similar .

The relay will connect and disconnect the power between a charger and a cellphone.

ProjectBegins: The relay will connect and disconnect the power between a charger and a cellphone.

Then use a Mosfet, much simpler and cheaper. With DC currents it's not worth to use a relay.