Originally Posted by
Winfried
After going the whole thread and taking notes, I have a couple more newbie questions:
1. Contributions above suggest getting a car horn that "pulls" about 6A: I read that it's very high current, especially in the rain. What parts should I use to build a safe horn + battery + trigger combo?
It's not that high, and the rain has nothing to do with it.
As for what to use, any automotive horn relay and any switch will do. You could do without the relay, but you'd need a pretty big switch (at least big from the standpoint of mounting on your handlebars.)
If you wanted to test it "on the cheap", you could buy a household 110v wall switch for $1 at Home Depot or Walmart and use that -- this isn't what it's designed for, but it would work. With that, you could do without a relay. But to do it right, you should get a few dollar relay and any switch you like and then wire it all appropriately. The relay may come with a little diagram telling how it should be wired.
Just show up at Pep Boys and say you need a horn, a horn relay and a switch for it. They should be able to help you get the right stuff.
nerys answered all these questions appropriately.
Note that gel cell batteries aren't designed for high discharge rates, so I wouldn't go much smaller than 2.3Ah or it might begin to sound weak. But 2.3Ah is probably fine, and as nerys said, it would give you 20 minutes or so of honking -- which is a lot.