Horn relay yes or no?
#1
Horn relay yes or no?
Did the 48 F-1's come with a horn relay from the factory? My new wiring harness from Sacramento vintage ford wires directly to the horn. My truck has an old relay on the inside driver fender well in front of the radiator. Some I have asked said they didn't have one, same say they did.
#4
#5
Double the voltage, but half the current. My '50 F-6 had no relay but I'm installing one. I only want minimal current going through the horn button contacts.
#7
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#8
Using 15 amps as indicated in Ross' post above, we can work this backwards to find the approximate resistance of the horns:
R = V/I or 6/15 = 0.4
Plugging that back into the original formula but with 12V, we get:
I = V/R or 12/0.4 = 30 amps
#9
Actually, if your resistance stays the same (ie - you don't change your horn), double the voltage also doubles the current. Ohm's law: I = V/R
Using 15 amps as indicated in Ross' post above, we can work this backwards to find the approximate resistance of the horns:
R = V/I or 6/15 = 0.4
Plugging that back into the original formula but with 12V, we get:
I = V/R or 12/0.4 = 30 amps
Using 15 amps as indicated in Ross' post above, we can work this backwards to find the approximate resistance of the horns:
R = V/I or 6/15 = 0.4
Plugging that back into the original formula but with 12V, we get:
I = V/R or 12/0.4 = 30 amps
#10
Actually, if your resistance stays the same (ie - you don't change your horn), double the voltage also doubles the current. Ohm's law: I = V/R
Using 15 amps as indicated in Ross' post above, we can work this backwards to find the approximate resistance of the horns:
R = V/I or 6/15 = 0.4
Plugging that back into the original formula but with 12V, we get:
I = V/R or 12/0.4 = 30 amps
Using 15 amps as indicated in Ross' post above, we can work this backwards to find the approximate resistance of the horns:
R = V/I or 6/15 = 0.4
Plugging that back into the original formula but with 12V, we get:
I = V/R or 12/0.4 = 30 amps
Here's Ohm's Law:
Ohm's Law
#11
#12
#13
I should also have added that you should always use a horn relay to minimize the current draw on the horn button contacts. The same goes for any high current draw, headlights etc. If you look at what Detroit does today they run almost every thing in light gauge wiring and use a relay to handle the higher current flow.
#14
And now I wonder why all this time we've heard that a 6 volt system has to have heavier gauge wires because the current is double that of a 12 volt system when in fact, it is exactly half that of a 12 volt system. Can anyone explain this?
Here's Ohm's Law:
Ohm's Law
Here's Ohm's Law:
Ohm's Law
What is confusing is that a 6V heater motor and a 12V heater motor will draw about the same current if driven by the designed voltage. If you run a 6V heater motor on 12V, it will spin twice as fast and use twice the current. Wattage doesn't really come into play because you're comparing two different systems...
To further confusing things - anything with a coil is subject to magnetic inductance as well - so while Ohm's law works, it's not useful for exact numbers out of the equation. The principles still apply, but it's not a true direct relationship necessarily. This is why motors don't play by the same rules as light bulbs.
#15