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Jeffrice
Jeffrice

Posted: Mon Oct 19, 2015 5:39pm

Post Subject: Horn/electrics

Hi there, I keep getting an intermittent problem with my boat's horn. It works at first but ceases after a few uses. If I remove the horn and add its contacts directly across a battery, it sounds. I can then reinstall it and it'll work for a while. The horn is located at the front of the boat, the battery at the other end. Using a meter, I can get a voltage reading at the horn, so the button isn't the problem. The long length of cable from horn to battery is suitably thick (I'd say). Any ideas?

Tony-B
Tony-B

Posted: Mon Oct 19, 2015 6:49pm

Post Subject: Horn/electrics

What actual facts and calculations are you basing your assertion that you would say the cable is thick enough? I also note that you say that you "get a voltage" at the horn end of the cables but do not quantify it. You also do not quantify the voltage between the live horn button contact and any negative connection. This makes it impossible to give you a definitive answer. On the basis of the few actual facts you have provided I would suggest that the cable may well be undersized but to be more sure I need those voltage readings. Take the voltage at the horn end with the horn connected and the button pressed. Take the voltage at the battery side of the button with the horn connected and button pressed. Then come back and tell me. If you attempt to measure the amps a horn is drawing when sounding it is likely to be about half of that needed to start it sounding so any loss of amps or the voltage to push the amps through the horn could well result in your symptoms. If you add a bit of voltdrop along the cable with lower voltage from the battery(s) this is the sort of thing you get. Sometimes the horn makes a single click and nothing else. Lets see the voltage readings and we can go from there.

Jeffrice
Jeffrice

Posted: Thu Feb 25, 2016 3:07pm

Post Subject: Horn/electrics

Hi Tony, Well, it's starting to get to that time of year for fiddling with boats, so I'm now coming back to this problem. The answer to your question is - 12V at both ends. Horn is currently working.

Tony-B
Tony-B

Posted: Thu Feb 25, 2016 5:11pm

Post Subject: Horn/electrics

It is still not clear if the 12 volts at the horn end is with the horn blowing or not. If it is then check all the connections but it is probably a faulty or water filled horn. If not then test it again but with the horn sounding. If it in excess of 12V (sounding) then the horn is probably faulty. If less then its undersized wiring, loose/dirty connections, or a faulty horn switch. If you have solar or shore power charging those symptoms could even indicate a battery problem like under charging causing a low voltage last year.

Jeffrice
Jeffrice

Posted: Thu Feb 25, 2016 5:30pm

Post Subject: Horn/electrics

Thanks Tony

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