Relay Tips

How A Relay Works

What is a relay?

A relay is a switch. It makes
and breaks a contact like any
ordinary switch. A relay uses
a small electro-magnet to
"pull" the switch on. When
the electro-magnet is turned
off the switch returns to its
original position. The idea
is that a small current
through the electro-magnet
flips a switch capable of
switching a much larger
current.

The diagrams to the right
illustrate what happens when
the electro-magnet is on and
off.

Relay with electro-magnet off.
Pin numbers are for standard automotive
type relays like the ones we sell.

Why do we need relays?

Some devices like our charge
controller can't switch
a high current directly.
Instead it turns the electro-
magnet on inside the relay.
The electro-magnet then "pulls"
the switch on that can handle
the high current.

Another reason to use a relay
is isolation. Since the
electro-magnet is not in
direct contact with the high
current switch, the circuit
driving the electro-magnet is
isolated from the high
current. This is especially
important for sensitive
electronics.

To see a picture of
or to purchase a relay
Click Here   

Relay with electro-magnet on