Rosco86
|
| posted on 6/11/15 at 12:38 PM |
|
|
Horn wiring
Right, ive had a bit of a search but not found much,
I'm using two Mixo horns (i cant seem to find out the amperage) wired through a relay with a 10 amp fused feed, and a momentary toggle switch,
I'm using 0.5mm2 cable which is rated at 11 amps,
it all works fine if you just blip the switch but if you hold it down it sounds funny, as if there's a loss of power or something??
my next thing to try is larger cable as it is a bit of a run from the relay to the horns, also the two horns are wired to earth as is the relay and
the horns are wired in parallel
any one got any ideas?
My Build Thread
|
|
|
|
|
gremlin1234
|
| posted on 6/11/15 at 01:32 PM |
|
|
horns do use a lot of power, probably about 8A each
try them one at a time. also try them with the engine running.
also this page may help
http://p-car.com/diy/hornrepair/
|
|
|
Smoking Frog
|
| posted on 6/11/15 at 02:26 PM |
|
|
If the horns are 8A each and the cable length 2m you need 2.00mm2 or 2.5mm2 cable with a 20A fuse. And don't forget the earth lead also
need to be at least the same cross sectional area. My guess is the existing cable is heating up and increasing the resistance resulting in poor
performance.
|
|
|
Rosco86
|
| posted on 6/11/15 at 08:47 PM |
|
|
quote:
Originally posted by Smoking Frog
If the horns are 8A each and the cable length 2m you need 2.00mm2 or 2.5mm2 cable with a 20A fuse. And don't forget the earth lead also
need to be at least the same cross sectional area. My guess is the existing cable is heating up and increasing the resistance resulting in poor
performance.
Ok thanks, can you explain how you worked this out? Regarding cable length etc
Also it works fine with the engine running so does this suggest that the wire size is ok?
My Build Thread
|
|
|
britishtrident
|
| posted on 6/11/15 at 09:00 PM |
|
|
Check what happens to the battery terminal voltage when you press the horn,
If it stays over approx 12.4v You need to check voltage drops when you press the horn button
(1) Check the voltage drop between horn earth terminal and the battery negative.
(2) Check the the voltage drop between the battery positive terminal and the horn positive,
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
britishtrident
|
| posted on 6/11/15 at 09:14 PM |
|
|
This Schrodingers Box Youtube vid might help https://www.youtube.com/watch?v=DfLyh43iihM It is about starter circuit testing but the principle is
the same.
[Edited on 6/11/15 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
Smoking Frog
|
| posted on 6/11/15 at 09:28 PM |
|
|
quote:
Originally posted by Rosco86
quote:
Originally posted by Smoking Frog
If the horns are 8A each and the cable length 2m you need 2.00mm2 or 2.5mm2 cable with a 20A fuse. And don't forget the earth lead also
need to be at least the same cross sectional area. My guess is the existing cable is heating up and increasing the resistance resulting in poor
performance.
Ok thanks, can you explain how you worked this out? Regarding cable length etc
Also it works fine with the engine running so does this suggest that the wire size is ok?
This some calculations here which may help.
http://www.locostbuilders.co.uk/viewthread.php?tid=197694
As regards to the existing cable being ok, I can't say without knowing the length of cable and the load (amps or watts), but 0.5mm2 cable
don't seem large enough to me.
|
|
|
britishtrident
|
| posted on 7/11/15 at 08:16 AM |
|
|
It won't be a cable size issue, the horns are not drawing 8 amps each they fed through 10 amp fuse!
Battery voltage dropping under load is the most likely suspect, then voltage drop through bad grounds.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
ste
|
| posted on 7/11/15 at 06:03 PM |
|
|
quote:
Originally posted by britishtrident
It won't be a cable size issue, the horns are not drawing 8 amps each they fed through 10 amp fuse!
Battery voltage dropping under load is the most likely suspect, then voltage drop through bad grounds.
They draw 10A each
|
|
|
ste
|
| posted on 7/11/15 at 06:05 PM |
|
|
spec sheet here
https://www.haladjian.fr/wpc/img_basse_def/FT_03683257_65_en.pdf
|
|
|
Rosco86
|
| posted on 7/11/15 at 06:27 PM |
|
|
Cheers for the help guys! If there 10amps each how come the fuse isn't blowing? Or is the wire size limiting the current, I'm still to
check the voltage drop, will try and have a look tomorrow
My Build Thread
|
|
|
