Winfried

Hello

12V car horns are a bit heavy and use 18-30A (eg. the Screaming Banshee) to run so aren't a good solution on a bicycle.

OTOH, a single-tone, 12V motorcycle horn uses much less current (1.5A) but sounds feeble and not anything like a car horn.

Also, to complicate matters, li-po batteries for use on remote-controlled toys aren't available in 6V or 12, but rather 7.4V or 11.1V formats. But then, 12V lead batteries are big and heavy.

So I was wondering if someone knew of a good compromise in terms of weight and current for use on a bicycle.

Thank you.

fietsbob

I want a Godzilla Horn !

dougmc

3s -- "11.1v nominal" -- lipo packs start out at 12.60 volts fully charged and go down from there. 11.0 volts (at which point the battery is over half discharged) will run a car horn just fine, and a 20C 2000 mAh pack is rated at 40 amps -- far more than you need. It'll run your 20A (to pick a figure) horn for six minutes, though really, I think that even 18 amps is on the high end of current draw. (Wikipedia says the typical car horn draws 5-6 amps, though of course some will be higher, like your 18A screaming banshee. Many cars use two horns, but even so, that's only twelve amps total typically.)

You could also use a 4s pack -- starts at 16.4 volts fully charged, 14.4 volts nominal -- and that will run a horn too, making it even higher pitched and even louder than a 13.8 volt car electrical system.

In short, a 3s or 4s 2 Ah R/C LiPo pack should be perfect. Just make sure you use a switch that can handle the amperage draw, or that you use a relay.

Winfried

Thanks Doug for the infos. I thought providing a device with a higher tension than it expects would damage it.

To lower the total weight, I'm thinking of only using one of those two car horns. Based on what the provided relay says, they expect 30A. Do you think it'd be OK to simply run wires directly between a single horn and a 4s battery pack?

I read that the role of a relay is to lower the current, so that it's possible to run a thinner wire between the relay and the switch on the handlebar.

dougmc

Slightly higher than normal voltages rarely hurts things like motors and buzzers. (It can hurt incandescent lights and devices with electronics, depending on how the voltages are regulated.)

You can just use one horn, but they sound better in pairs, as they tend to have slightly different frequencies and so people can hear the "warble" of the beats created. If you want to really sound like a car, use both. But one will get people's attention too.

The relay is larger than the application requires -- not unusual, nothing wrong with that. The horns you linked to will probably use around six amps each, so even two of them would still be easily doable.

The role of the relay is to allow you to use a small switch and small wires to the switch. If you use a heavy duty switch and wires that can handle 15 amps, you can do away with the relay entirely. Or you can use the relay with small wires to the switch, and heavy duty wires between the battery, horn and relay. Your choice. You should also wire in a 30 amp fuse, just in case something goes wrong.

Note that the battery you linked is 5000 mAh -- huge. Assuming you use both horns, that should run it for twenty five minutes of solid horn usage -- which would probably last a normal person over a year. You don't need anywhere near that big of a battery -- 1000 mAh or 2000 mAh would probably be just fine. The hard case is nice, however.

And note that Turnigy batteries come from hobbyking.com -- you might want to consider ordering directly from them instead of eBay as the prices may be better. Also make sure you have a LiPo charger, and don't let your battery get below 3.0 volts/cell or you'll ruin it. (These batteries do not come with protective circuits that prevent that.) You shouldn't need to charge your battery often (once a month?), but when you do, do pay attention to the instructions -- these are the batteries that can burn if abused.

Winfried

Thanks much for the enlightment. I'll go to an electronics store pick up the parts I need and experiment.

Winfried

I went to a couple of electronics stores and they recommended I use a lead battery instead of a li-ion/nimh battery because of the amps the horns need... but lead batteries are just too heavy.

As a lighter alternative, I was thinking of feeding an MP3 to a compact megaphone with an amplifier between the audio source and the megaphone.

If all else fails, there's the hand air pump solution :-)

dougmc

Then they don't know what they're talking about. They just don't realize how awesome these R/C packs are at handing high discharge rates nowadays.

Also note that we've been talking about lipo packs, not nimh or even li-ion.

That 5000 mAh battery pack you listed? It's rated at 20C continuous, 30C burst. Car horns are very much a "burst" activity, and 30 * 5 Amps = 150 amps, and you probably only need around twelve amps even for a pair of horns.

That single battery could power twenty horns simultaneously as long as you kept it to a few seconds per use, and it could power sixteen horns steady for a few minutes (until the battery died.) And you only need two.

Even if you pick a more reasonably sized 2000 mAh pack, and if it's rated at 20C continuous/30C burst (and you can easily get higher C ratings than that) -- that's still 60 amps burst when you probably need around twelve.

SmallFront

Li-ion is able to deliver a lot of amps in a very short while - nimh not so much.

In any case, here is a bit involved horn (system) that may be over the top:

https://screaming-banshee.com/

Or, do as many motorcyclists do: Buy a Stebel Nautilus horn: It's small and it's powerful.

https://www.google.dk/search?q=Stebe...Femo4ATW5YCQAQ

SmallFront

Btw, if it was me looking to install a powerfull horn, I would go for a LiFePo4 battery (pack).

dbg

Those air pump horns are really loud and weigh almost nothing. I have one but have never mounted it on a bike.

anga

If you are looking for a really loud horn, hornit works. Not sure how close it is to a car horn.
https://www.thehornit.com

cplager

It's not as loud as an Air Zound, nor does it sound as horn like. But it works in the cold and I don't need to remember to fill it up.

anga

Here's what their websites claim.

Airzound: Super Loud 115 db

Hornit:
[TABLE="width: 100%"]
[TR]
[TD] 'Road' mode output [/TD]
[TD="colspan: 2"] 140 decibels[/TD]
[/TR]
[TR]
[TD] ‘Park’ mode output[/TD]
[TD="colspan: 2"] 130 decibels[/TD]
[/TR]
[TR]
[TD="colspan: 3"][/TD]
[/TR]
[/TABLE]

cplager

I own then both and find that I get much better reactions using the air Zound. The Hornit doesn't sound enough like a horn.

dougmc

These ratings at what distance? Unfortunately, the decibels rating of a noise maker depends on how (at what distance) you measure it, and if you don't know the specifics of how they measured it, it's difficult to accurately compare two ratings from different sources.

For example, 140 db vs 115 db , if measured in the same way, would mean that the Hornit in road mode puts out about 300 times the sound energy as the airzound. I've never seen or heard a hornit, but I find this claim to be unlikely.

Also, 140 db is loud enough to cause instantaneous and permanent damage to your hearing. Maybe it's 140 db at an inch?

Athens80

The banshee claims 139db at 10 centimeters.

anga

I own both, use both, and both work well.
But Hornit sounds louder.

It goes without saying that any measurement depends on how it was measured!!
Since neither site states how decibels were measured, seems reasonable to assume that they were putting the best possible numbers forward.
For example, the wiki page states One could again argue that one of the two produces sound at frequencies at which the human ear is more sensitive and hence sounds louder than the measurement indicates.

My position is that hornit is louder: from claimed numbers and perception.
Effectiveness: both work well. Hard to test relative effectiveness.

01 CAt Man Do

I've viewed some of the video's of the hornit. Problem is they don't show what I want to see. I want to see a video of someone sitting in a car ( windows up ) with radio at moderate volume and have a cyclist approach from the front and have them start hitting the horn @ 100 ft. until just in front of the car. When finished I'd like a repeat but this time from the rear If you can hear the horn inside the car from 100ft, I don't care what frequency it is it should draw attention. Something like sounds more like a car would be better but I'd like to use something that is small and easy to mount with remote.

I figure it this way; the Airzound will garner attention with just a quick toot. With the hornit you will likely need to really "Lay on it" to get the same reaction.

anga

Your conclusion is just an assumption.

cplager

My personal experience with both are consistent with his assumption. The Hornit doesn't get recognized as quickly as a horn, it sounds almost more like a car alarm.

01 CAt Man Do

Correct. A good assumption has the potential to save your life. Remember, it's not the horn that saves your life. Rather it's the person being alerted to your presence in an inclosed 2 ton vehicle who might otherwise run you over but decides not to once he see's or hears you. Regardless, If I owned either type of horn the first thing I would do would be to test it like I said in my previous post. To me the important issue is not whither one is a certain tone or louder at 1m. If both can be equally heard by a person with normal hearing inside an enclosed car ( under normal conditions ) that would be good enough for me to consider buying either one. After that the deciding factor on which I would prefer would likely be about size, remote options, visual aesthetics and tone options.

Tone of course is an important issue. Something that sounds more like a car horn should have the added advantage of "instant recognition" to motorist driving down a road. Just how important that would be would depend on the person doing the hearing and how they react to different tones that they may or may not previously identify with.

ThomasMcA

Have you tried an Airzound? It sounds like the airhorn from an 18-wheeler.

I once had a pickup truck back out of a driveway, right in front of me, while I was clipping along at about 25mph. I blasted my Airzound, and he pulled off the road in a hurry, half on his grass and half on his driveway. It scared the crap out of him so much that he just wanted to get the h*ll out of the way of whatever he didn't see.

anga

^^ A good assumption can help and a bad assumption can hurt--hard to argue with that.
The point is it is still an assumption and you cannot conclude based on an assumption!!

cplager

The issues I have with the Air Zound is that (1) it doesn't last as long as I'd like (but you can mitigate this by refilling it weekly) and it has been known to have issues in the cold.

I found the sound on the Air Zound to be much more efficient in eliciting the desired response from motorists, where as the Hornit doesn't seem to have such a instantly recognizable sound (it's loud sound sounds more like a car alarm than a horn). It lasts "forever" and works just fine in the cold, however.

I'll be very interested to hear what the OP ends up with. I've been thinking along the same lines as it may be just like the Hornit, but with a better sound.