6 Volt Horn Power Needs Model A & Others

[leo]

I've just gone through all the previous posts regarding amp requirements for 6 volt Model A horns. The consensus is that it takes 5 amps to blow the horn, with some estimates as high as 10 amps. Why the large variance? My question regards a 6 volt E. A. Laboratories Model S, how many amps does it require to blow?

[SeaSlugs]

it requires enough haha.

Many reasons can factor in amp draw - how tight the adjusting screw is (aka one mans ahooga may not be anothers), if the motor bushings have lube and aligned, how good of contact the brushes have to the comutator (poor contact has high resistance and amps must go up to do the same job), how good of contacts the wires going to it have, how clean grounds are etc.

id imagine even new they would vary a bit.

[Mikeinnj]

Brattons sells a horn relay that mounts inside your horn cover and eliminates any horn drag
Double Click on photo to enlarge view

[Mike V. Florida]

Originally Posted by SeaSlugs

it requires enough haha.

Many reasons can factor in amp draw - how tight the adjusting screw is (aka one mans ahooga may not be anothers), if the motor bushings have lube and aligned, how good of contact the brushes have to the comutator (poor contact has high resistance and amps must go up to do the same job), how good of contacts the wires going to it have, how clean grounds are etc.

id imagine even new they would vary a bit.

That seems to cover it.

[Mike V. Florida]

Originally Posted by Mikeinnj

Brattons sells a horn relay that mounts inside your horn cover and eliminates any horn drag
Double Click on photo to enlarge view

The relay helps with bad grounds. Resistance from a bad ground, like in the horn button, drops more voltage with high current. The relay uses very low current to switch the current for the horn. So the same resistance will operate the relay but would have made the horn sound bad.

[Tom Wesenberg]

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My horn runs at 5 amps, but to start the armature spinning and to make it roll over the first bump of the wavy washer could easily take 10 amps. That why you should use a battery to test horns rather than a 6 amp battery charger. Also the battery gives a smooth source of power, rather than the ripple from a half or full wave rectifier from a battery charger.