12 v horn problem

[Alan de Enfield]

1 minute ago, ditchcrawler said:

Now if boats had 2 batteries installed in the bows?

Norty !

[NewCanalBoy]

1 hour ago, David Mack said:

When the CRT guy was checking Belfast over before I could go through Harecastle Tunnel, the horn didn't work. "Try it with the engine running" he said. That worked. So I was OK to go, as long as the engine didn't fail in the tunnel!

Or maybe just the ignition needs to be on ?

 

Hasn't somebody said that already ...........

[WotEver]

48 minutes ago, NewCanalBoy said:

Or maybe just the ignition needs to be on ?

 

Hasn't somebody said that already ...........

I think the point was that it didn't work at 12.xV but did work at circa 14V when the engine was running.  However... you could be right

2 hours ago, Alan de Enfield said:

I've got the bit between my teeth on 'volt drop'

Me too  We'll find out in due course I guess.

[Greg & Jax]

Hi guys .

I think what's happened as was pointed out I now have a much louder horn than the previous one .

I will get to having a look after the sun eases off a bit .

Carnt thank you all enough .

Cheers Greg. 

[Alan de Enfield]

28 minutes ago, Greg & Jax said:

Hi guys .

I think what's happened as was pointed out I now have a much louder horn than the previous one .

I will get to having a look after the sun eases off a bit .

Carnt thank you all enough .

Cheers Greg. 

I think it is not just the 'loudness' but  rather the current. 12 amps on a short run of a car or truck needs very different wiring to a 50+ foot long boat.

Should it turn out to be the problem, it again typifies the problem with using 'automotive' electricians to wire up boats. 

yes - it is still 12v but there are totally different criteria to be considered.

 

(Not suggesting that your boat was wired up wrongly by an auto-electrician, it was quite probably wired up correctly for the equipment that it was wired up to supply)

 

I suppose it could be looked at as putting a 5 litre V8 engine into a mini, the old fuel pipes cannot supply enough fuel, the gearbox cannot cope with the 'power', the brakes cannot stop the car.

 

It can be easily proven by doing the test using THICK wires over a long length, or getting another horn with a much lower current demand and trying it on the existing wiring.

 

Or, I could be totally wrong and its not down to volt-drop.

[Greg & Jax]

Hi guys .

Just been playing with the thing .and here is what I have found .

I connected the meter and have about 00.7  press the horn switch it goes to 12 .7 all without horn connected .although is does fluctuate up n down  some .

I connect the horn to neg reading 00.7 then connect the pos and it goes to -0.00 even when switch is pressed .

All while engine running 

So things are as clear as mud .

Regards Greg. 

[Tracy D'arth]

Its the wiring! You have a lousy connection somewhere between the battery and the horn. Could even be the horn push.

Edited May 29, 2020 by Tracy D'arth

[Alan de Enfield]

9 minutes ago, Greg & Jax said:

Hi guys .

Just been playing with the thing .and here is what I have found .

I connected the meter and have about 00.7  press the horn switch it goes to 12 .7 all without horn connected .although is does fluctuate up n down  some .

I connect the horn to neg reading 00.7 then connect the pos and it goes to -0.00 even when switch is pressed .

All while engine running 

So things are as clear as mud .

Regards Greg. 

Where are you putting the test probes - it sort of reads that you are probing at the actual switch / button.

 

Voltage should be 0 (zero) and 12+ volts when pressed.

 

If the voltage goes down to 0 (zero) with the horn connected and the button pressed that would suggest a 'HUGE' current draw pulling the voltage right down

 

Can you describe what and where you are testing.

What size of cable is it (is it printed on it ?) even the overall diameter would let us work out roughly the conductor size.

[Greg & Jax]

Hi guys . 

Well I have just connected a 5mm square arctic blue cable about 70 foot my old spare hook up . 

Connected to starter battery and touched to the pos n neg and behold a big old horn sound he he . 

So I have a problem in my horn wiring .

Regards Greg. 

[Alan de Enfield]

1 minute ago, Greg & Jax said:

So I have a problem in my horn wiring .

 

1st step 'sorted'

 

[Mike Adams]

While this is a different scenerio to the one that was first posted my first check would be the switch. Bypass it and then connect the horn. These horns take a large current and the switch might not be up to it otherwise a bad connection anywhere in the circuit. Check what happens each side of the switch - both contacts should remain at +12v when the switch is pressed. Good luck!

[Alan de Enfield]

 

 

Now, find something else that 'draws a bit of juice', connect it up to the 'old' horn wiring and see if it works.

 

Old style car headlight bulb draws about 4 amps. If that works OK then the problem would suggest to me that the cable is too small for 12 amps over that distance.

 

Edit - in fact, thinking about it, what is your front light like ?

Could you connect it to the horn wiring ?

Edited May 29, 2020 by Alan de Enfield

[Greg & Jax]

I detect be beginning of the end to my Horny problem? 

Regards all 

[Greg & Jax]

Hi guys . 

Thanks for all the help from you all ,so meny nice people willing to help out .

Warms the cockles of my heart. 

and yes Alan I'm going to swap the headlight and the horn over tomorrow see how that works out .

Regards Greg. 

[Tracy D'arth]

Make it simple and just rewire it, with a decent gauge of cable.

[ditchcrawler]

1 hour ago, Alan de Enfield said:

 

If the voltage goes down to 0 (zero) with the horn connected and the button pressed that would suggest a 'HUGE' current draw pulling the voltage right down

 

Or there is a gap stopping the wigglies getting through

38 minutes ago, Tracy D'arth said:

Make it simple and just rewire it, with a decent gauge of cable.

It may not be the cable, it could be the horn push, corroded fuse, knackered relay (if fitted) or just a bad connection somewhere

[Alan de Enfield]

7 minutes ago, ditchcrawler said:

Or there is a gap stopping the wigglies getting through

It may not be the cable, it could be the horn push, corroded fuse, knackered relay (if fitted) or just a bad connection somewhere

You may be right but easily checked by trying a light (or something)

 

At least we now know that given an 'unbroken' cable of sufficient CSA the horn will work.

[WotEver]

28 minutes ago, Alan de Enfield said:

At least we now know that given an 'unbroken' cable of sufficient CSA the horn will work.

See post 2

[Sir Nibble]

Here's my own radical solution to horn cable volt drop. Mount the horn at the stern and do away with the long cable run completely. There's no reason at all why it needs to be at the front.

[Jen-in-Wellies]

49 minutes ago, Sir Nibble said:

Here's my own radical solution to horn cable volt drop. Mount the horn at the stern and do away with the long cable run completely. There's no reason at all why it needs to be at the front.

Quite right. The only disadvantage of having the horn at the stern is that you deafen yourself, rather than the person obliviously speeding towards the bridge hole on a blind bend. It is also more traditionally narrow boaty than having it at the bow if that is a consideration.

Jen

Edited May 30, 2020 by Jen-in-Wellies

[Stilllearning]

13 hours ago, ditchcrawler said:

Or there is a gap stopping the wigglies getting through

It may not be the cable, it could be the horn push, corroded fuse, knackered relay (if fitted) or just a bad connection somewhere

And there is no such thing as a simple rewiring job, from the back to the front of a boat!

ETA

its on a par with the Haynes manual instruction for my old mk 4 Sprite, to change the clutch, first remove the engine....

Edited May 30, 2020 by Stilllearning

[Greg & Jax]

Hi guys .

Well after going through all the ideas I receaved from all the reply,s 

I put a direct feed to the horn bypassing the circuit breaker  the horn worked a treat , so then traced the switch cable checked the switch . All good . 

Then I took the whole circuit breaker panel off to have a look see and it turns out the breaker is only ten amps and and my lights are 15 amp so I swapped them round and my horn works a treat . 

So I will now get a 15 amp breaker switch and all is fixed  . 

Thankyou all so much for the help with this , I also feel a lot more confident in  dealing with the 12 v system after taking the curcuit board  apart tracing what goes where labelling them all and putting it back together .

❤ thankyou Greg. 

 

 

[ditchcrawler]

35 minutes ago, Greg & Jax said:

Hi guys .

Well after going through all the ideas I receaved from all the reply,s 

I put a direct feed to the horn bypassing the circuit breaker  the horn worked a treat , so then traced the switch cable checked the switch . All good . 

Then I took the whole circuit breaker panel off to have a look see and it turns out the breaker is only ten amps and and my lights are 15 amp so I swapped them round and my horn works a treat . 

So I will now get a 15 amp breaker switch and all is fixed  . 

Thankyou all so much for the help with this , I also feel a lot more confident in  dealing with the 12 v system after taking the curcuit board  apart tracing what goes where labelling them all and putting it back together .

❤ thankyou Greg. 

 

 

Its not the rating of the breaker, Its ether a dodgy breaker or one of the connections you disturbed changing it was dodgy,  Breakers don't limit cuttent they just sometimes open on overload

[WotEver]

1 minute ago, ditchcrawler said:

Its not the rating of the breaker, Its ether a dodgy breaker or one of the connections you disturbed changing it was dodgy,  Breakers don't limit cuttent they just sometimes open on overload

The bold bit. 

[Greg & Jax]

Thanks again .

I  will now go and see about swapping it for another 10 amp breaker .

Cheers Greg