power required for 12v 80 amp relay?
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=131581
Printed Date: July 04, 2025 at 7:09 AM
Topic: power required for 12v 80 amp relay?
Posted By: dzlxzzia
Subject: power required for 12v 80 amp relay?
Date Posted: June 10, 2012 at 5:12 PM
Hello,
I need to power/activate an 80 amp relay (to turn on an 600 watt amplifier). I'd like to use the switched wire coming from my head unit (HU), but am afraid the current required to activate and hold the relay on and my amp on might blow out the HU.
The relay will e something like this
-will a typical HU switching wire for firing up amps work?
-if not, likely amp requirements and wire gauge?
Thanks much, D-
P.S. apologies if I'm not using the right terminology.
Replies:
Posted By: i am an idiot
Date Posted: June 10, 2012 at 5:36 PM
When you get the relay, check the resistance across the coil and post that info here. Most remote wires are capable of providing 200 milliamps of current. A Tyco SPDT relay draws 160 milliamps of current.
Posted By: i am an idiot
Date Posted: June 10, 2012 at 5:47 PM
Let us know how that relay holds up.
Posted By: dzlxzzia
Date Posted: June 11, 2012 at 12:15 AM
i am an idiot wrote:
When you get the relay, check the resistance across the coil and post that info here. Most remote wires are capable of providing 200 milliamps of current. A Tyco SPDT relay draws 160 milliamps of current.
Thanks,
Thats good to hear. I'd of thought a relay like that would be a pretty good load just to close it but, I don't really know anything about these aside from the obvious.
I'll keep you posted,
D-
Posted By: howie ll
Date Posted: June 12, 2012 at 7:24 AM
Aren't we missing something here Craig?
Why would you even need a relay for one amp.
They have their own inbuilt relays or electronic switches.
If you had multiple amps which haven't been mentioned you still wouldn't need more than about 2 amps.
Our OP could try to wire it direct via a 1 amp fuse just to see.
Or even meter the draw to trigger that amp, betcha it's about 100 milliamps.
-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: i am an idiot
Date Posted: June 12, 2012 at 8:38 AM
His amp is staying on even without the remote wire being connected.
Posted By: howie ll
Date Posted: June 12, 2012 at 9:31 AM
Are you doing your crystal ball routine again?
I can't see where he says that.
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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: howie ll
Date Posted: June 12, 2012 at 9:36 AM
Sorry, just read the previous posts from the OP. I'm with DYJohn here.
The relay idea is going to be a train wreck.
-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
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