relays can you keep the power on?

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=126184
Printed Date: May 16, 2025 at 7:15 PM

Topic: relays can you keep the power on?

Posted By: chaminda
Subject: relays can you keep the power on?
Date Posted: February 16, 2011 at 8:44 PM

Hi
This may seem a stupid question.

Most of the circuits I've seen with relays puts a brief (momentary) current through the coil.

I was wondering what happens with if you keep a constant current through the coil for a long time? Except the switch being on can it damage the coil or overheat it?

thanks

Replies:

Posted By: i am an idiot
Date Posted: February 16, 2011 at 9:29 PM

A Bosch/Now Tyco relay is a constant duty device. No harm will come to the relay even if it is energized for weeks on end. It will however run down a cars battery if left energized without having the motor running. It will take a day or 2, but it will go dead.

Posted By: chaminda
Date Posted: February 17, 2011 at 2:35 AM

hi
Thanks for the reply.
I'm using a 12v relay (JQX-115f - not sure of the manufacturer) and a omron DPDT latch relay.
I can do a circuit so that it only sends a pulse but would mean a whole lot more work. The circuit will only be on when the cars on so no risk of battery discharging.

Do you think it would be ok to keep the coil charged in these relays?
thanks

Posted By: i am an idiot
Date Posted: February 17, 2011 at 5:53 AM

I think it will be fine.

Posted By: howie ll
Date Posted: February 17, 2011 at 6:16 AM

With the accent on "THINK". What are you trying to achieve, can't you use just the latching relay?

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Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: oldspark
Date Posted: February 17, 2011 at 4:20 PM

Relays do handle constant on - unless not "continuously" rated as with some LARGE relays used for starter motors, winches etc.

Many relays in both industry and automotive use are permanentaly on as long as the equipment or vehicle is on. They are only off under certain circumstances (eg, the is an alarm, or the fan is needed, etc).
Those relays can last 20 years or longer.