How to Test a Relay with a 9V Battery

May 10, 2018

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How you can test if a relay is functioning properly?
To test the relay, you only need a 9V battery for the most basic test.

Relays have 3 kinds of terminals, coil terminals, NC and NO terminals.
NC is normally closed.
NO is normally open.
The Coil terminals control the state of the relay. Closed or open.

NC is letting electricity pass thru the relay when there is no voltage and electric current flow across the relay coil terminals.
When the coil is energized, the NO terminals, close and let electricity flow.

Just place the battery on the relay terminals that are connected to the relay coil.
When you place the 9 volts battery on the relay coil terminals, the relay will click.
Try the switching the + and – positive and negative terminals if the coil doesn’t work.