I replaced a drop in horn in my forward anchor box with a new 12v trumpet. The drop in functioned fine; however, wasn't loud enough to even hear in the cockpit. The new horn worked on initial test with battery voltage only. Three weeks later on the water it's dead on battery and while engine running. Back on land a test netted what sounds like a pop of the diaphragm and when hitting with my hand it will sound. I figured bad diaphragm and had the horn warrantied. Now the replacement does the same thing! Battery volts at the leads where the horn connects is 12.7v. Both horns work when jumping directly to a battery. Emailed manufacturer. What am I missing?

Thanks for any help you can lend
Keith

Probably needs thicker guage wire run to it. Run a test length of 10 guage wire from the switch to the horn.

Thicker wire is capable of carrying more amps. Current/amps will be determined by your load ie horn in this circuit. I'm assuming your voltage measurement is at the leads with no horn hooked up? Connect your horn and turn on. Meter again and see what your voltage is under load.

Voltage under load is 5v. Is that not normal if the horn is using energy to operate or should the voltage stay constant? The OE wire is 16 ga. and 15' long btw.

Keith

Too much of a voltage drop. Test run a thicker wire

Yes.
just like everything else.imagine if your ignition system/fuel system and vehicle electronics went to 5 volts under use. Like your horn, nothing would work.

Gotcha,

10ga wire in hand, if that fixes it I have no idea how I'm getting it from the helm to the anchor box in a permanent install. Cross that bridge when I get to it I guess.

I did run the boat this weekend and noticed a HUGE drop on the helm voltmeter when attempting to sound the horn with engine power. The gauge dove from 14v to 12v!! Seems extreme to sound a horn haha.

Keith

How many amps does the horn draw? Seems like you have a short somewhere.

3.5a, instructions only require 16 awg wire for 0-50' installation and I have 15'. I guess I pull the switch panel and check the switch back connections. Where else could there be a short?

Keith