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Discussion Starter #1
HI, I just got a set of dual air horn.(low tone and high tone) that uses a 12 volt , 10 watts, 8 ohms with a relay that draws 40 amps. So my question is if I can use this with my bike without messing with my electrical system. I planned to go straight from the battery to the relay with a 40 amps inline fuse. If any of you have done this before let me know.

Thanks. Ride safe.
 

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I am sure there are some better electricians out there than me, but here is my two cents worth. A relay is really smart. It protects the switch up on the handle bar from overload and burn out because of the new heavier amp load. I shiver to imagine how much it would cost to replace that switch.

First go to the link below for instructions and a wiring diagram. Your existing horn wires go on terminals 85 & 86. It does not matter which order. Your positive wire from battery goes to terminal 30. The wire to the air horn goes on 87. Then just ground the other air horn wire.
http://www.gadgetjq.com/airhorn.htm

Second, are you sure your horn only pulls 10 watts. Fuse size is determined by amp draw. Amp draw is equall to the watts divided by the volts.

100W / 12V = 8.3A (this is the way I figured fuse size for my driving lights)

Most of the air horns I have seen draw between 5-10 amps. Per your description it sounds like it would only draw .83 amps. That is REALLY low for an air compressor motor. Maybe it actually pulls 10 amps. In which case I would put in a 15 amp fuse. Just check your horn specs to make sure. I would not go with a 40 amp fuse. The point of a fuse is to break before something else burns up. At 40 amps, your horn or your relay could burn up before the fuse goes.
Good luck!
 

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Based upon my experience with my air horn, I suspect the 40 amp number is correct. My single came with a 20 amp fuse, and a 30 amp relay.

The relay is there to protect the switch, and the wiring. Burning up your wiring harness is likely an expensive repair..
 

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Discussion Starter #4
Hey, thanks for the quick response !! yea, you are right,I'm using a 30 amp fuse, by the way , the "operation power" reference state the uses 12 v., 10 watts ,. 8 ohms".
Thanks again and will post pics later.

Ride safe!!
 
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