wiring a car horn
Printed From: the12volt.com
Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=20418
Printed Date: August 15, 2025 at 2:15 PM
Topic: wiring a car horn
Posted By: cmunson
Subject: wiring a car horn
Date Posted: October 22, 2003 at 8:59 AM
This is probably going to be one of the strangest posts in here, but here goes. We are currently working on a Haunted House for my neighborhood and I need some help with one of our projects. We are creating a fake grill, bumper, hood, headlights, etc. and will have this hung on the wall at the far end of one of our hall ways. the idea here is as the group feels their way down the hall once a the end, we'll flip a switch that blasts the horn and turns on the head lights. I'm not really using real head lights so they'll be plugged into a regular 110 power strip. The horn is what's giving me the problems. I can get a horn from an auto parts store and everything I've seen says that it needs a 12 volt battery to power it. I was wondering if the 12 volt back up battery that's being used for my home alarm system would work? It is a 12 volt and it has positive and negative terminals (kind of like spade recepticles) on top. One's black and the other is red. I'm wondering if I can hook this up to the horn and then also could I hook up a switch to it. And...if all this would work, how would I accomplish this as the horn only has one wire coming off of it and the battery has two terminals? Sorry to sound dumb on this, but it's all new to me. Any help would be greatly appreciated!! Thanks
Replies:
Posted By: hotrodelectric
Date Posted: October 22, 2003 at 9:30 PM
It MIGHT. The problem is one of power consumption. A horn
takes a fair amount of amperage- I'd guess between 3-10 amps depending on a number of factors (coil size, wether or not it's a new horn, if the ground is adequate, etc.).
You also need a battery sized for the job- a battery that outputs, say, 750mA will definitely not do the job. A battery charger normally won't do it either- the output from most of them is 'pulsed'- not a steady stream of power. What you could do is use a barely functioning car or motorcycle battery, and hook a charger to it. The charger will keep the battery functional enough, and the battery acts as a filter, smoothing the pulses of the charger. You could also buy yourself one of those rechargable battery boxes (any serious car guy or gal should have one of these anyway, especially since they're so cheap), charge it up, then keep it plugged in and charging during your fright fest. Wiring your horn is far easier. The horn mount or mounting bolt is usually the ground. Make doubly sure it's a clean, solid ground connection to the battery negative, or your blast will wind up sounding like a sick baby elephant. The positive terminal will go to one side of your switch, your horn positive to the other. Use 14ga wire to do your hookups, and use a switch large enough amps-wise to do the job. One of those side-of-the-column ones should do what you want- just make sure you don't ground the terminals to the switch case. I would recommend a fuse (15A), but here I don't think it's a necessity. It will, however make it easier to disconnect quickly should the horn stick on.
Posted By: promodeepcycle
Date Posted: October 22, 2003 at 10:18 PM
usen a battery charger just get a good one need like 5 amp cont.
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dont be a pet monkey ..use your dmm
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