Magnum Blasters Without Relay

Guys,

I am a less is more kind of guy. And I do not mean to disparage the work of soooo many people, especially the Magnum Blaster harness, but is all of this wiring and relaying (new word) really necessary?

The stock horns are 3A @ 12V each = 6A. The Magnums are 6A each = 12A. Now 6A (the difference) isn't really a world of current. Considering the button is a mechanical contact type, isn't it probable that it can handle the 12A load? Yes, yes, I know it is 100% more, but I believe the switch can easily handle this load given its construction. This is a DC application. I would be more concerned if it were AC wrt arcing and wearing or carbonizing (another new word) the contacts.

So, my question stands. Has anyone been using the magnums (or other high power horn) with the stock wiring and switch for at least a little while?

At the very least I will not be installing mine with new cables routed to my fuseblock. This is totally unnecessary. I will just up the SIGNAL fuse by 5 or 10 A, then put a relay in line with the pink wire from the switch contact. It is the ground side of the circuit, so the pink will complete the ground side of the relay solenoid and the relay will close the path to ground to the pink wire downstream. One relay, one low current positive wire (to fuseblock) and one heavier gauge wire to ground.

Any thoughts are much appreciated.

-BD

I used the harness from Randy, maybe I didn't need it?? Well anyway wait till you hear those bad boys!!

I must confess, at the risk of being a soup sandwich eater, to not have relayed mine. No damage yet at 15K. I do have one not working, but think that's due to it's up position and collecting rainwater in the "Biblical" rain of the Utah 1088 last June.

One day I may solder my switch together and have permanent horn, but I feel so saucey living dangerously.

Good luck Brundog, that's all I can say.

problem #1....the Blasters are 7 amps each, which brings the total to 14, not 12.

Not a big jump from your amount, but still over 1005 more than capacity. The factory wiring is in no way capable of handling this amount of current for an extended period of time. Eventually, something somewhere WILL fail.

You'd be lucky if it was only your switch that went first. Usually the wiring will fry and take out others in the same loom, causing a much more serious problem.

problem #2.....never NEVER up the fuse rating to compensate for a higher current device!! Why?? see problem #1.

problem #3.......you paid for louder horns, right? Did you know those horns are working at around 60% volume if run through the factory wiring?

Those (or any high current) horns NEED a quick burst of current to operate at full volume. The 18 guage wiring for the fact. horns cannot supply 14 amps forever.

See this chart.

https://www.the12volt.com/info/recwirsz.asp

If you think I might have used a scare tactic to sell harnesses, you're wrong. And I'm not saying you're suggesting that, I'm just saying there's no need to even think that!

I could care less if no one bought a harness from me. When I originally posted that I made up an accessory harness to operate the Blaster horns to full capacity, I had no idea it would end up where it is now. But the fact is that I sold approx. 110 of them so far, and EVERYONE contacted ME. Not the other way around.

A little bit about me.

I've been selling/installing auto stereo, alarms, remote starters, etc etc for almost 19 years now. I've seen my share of burned wires because the customer thought he could "get away" with doing it his way.

Of course, you're free to do with your machine how you see fit.

I just thought I'd enlighten you on some of the facts.

One more fact...you can't buy the horn switch separately, it's part of the $115 assembly. My horn harness is $30 plus shipping....cheap insurance.

Guys,
I am a less is more kind of guy. And I do not mean to disparage the work of soooo many people, especially the Magnum Blaster harness, but is all of this wiring and relaying (new word) really necessary?

The stock horns are 3A @ 12V each = 6A. The Magnums are 6A each = 12A. Now 6A (the difference) isn't really a world of current. Considering the button is a mechanical contact type, isn't it probable that it can handle the 12A load? Yes, yes, I know it is 100% more, but I believe the switch can easily handle this load given its construction. This is a DC application. I would be more concerned if it were AC wrt arcing and wearing or carbonizing (another new word) the contacts.

So, my question stands. Has anyone been using the magnums (or other high power horn) with the stock wiring and switch for at least a little while?

At the very least I will not be installing mine with new cables routed to my fuseblock. This is totally unnecessary. I will just up the SIGNAL fuse by 5 or 10 A, then put a relay in line with the pink wire from the switch contact. It is the ground side of the circuit, so the pink will complete the ground side of the relay solenoid and the relay will close the path to ground to the pink wire downstream. One relay, one low current positive wire (to fuseblock) and one heavier gauge wire to ground.

Any thoughts are much appreciated.

-BD

Click to expand...

Hey BrunDog,

It's not all the amps and crap. It's how simple Randy's harness makes the install.

Even a drooling fool can do the install with his harness. :dribble: :dribble: :dribble:

Don't ask me how I know this.... :bleh:

Hey BDog

Spend the money mate and get the harness no hassels no wasting time no cooking the plastic!

Cheers

DC currents are more difficult for a switch to interrupt than AC currents. The reason is that AC currents pass through a zero voltage every cycle. In other words 60 Hz AC house voltage goes through zero volts at the mid-point of every cycle. DC currents don't. Having said that, the switch may work for sometime prior to failing. I doubt anyone other than the switch designers know the current density that it was designed for. One thing a horn circuit has going for it is that it is normally not used often. One doesn't know if this factor was included in the design of the switch or not. Now wiring. Generally speaking the wiring of electrical circuits is the weakest link. Fuses, & circuit breakers are put into circuits to protect the weakest link in the circuit which in turn protects the rest of the components. By not installing a relay with heavier conductors to supply the power you limit the size of the protective fuse for the wiring for the larger current load of the larger current draw of the new horns. Also there will be slightly more voltage drop in the smaller wires. I say "slightly" because the wiring isn't all that long & for any given conductor the voltage loss (dropped voltage) is proportional to the "Amp feet" or the number of amps carried over the number of feet of the conductor. By using a relay rated for the current total of the new horns & larger wire you are doing it in a correct manner from a design view point. From a cost viewpoint it becomes a question of how much the handlebar switch/wiring costs to replace verses the cost of heavier wiring & a relay. I put the relay & heavier wire on mine.

Even a drooling fool can do the install with his harness.    :dribble:   :dribble:   :dribble:

Click to expand...

x1 for sure!

My older brother always instilled an idea in my head that makes a whole lot of sense, ad has proven true time after time.

"Either do the job right, or don't do it at all."

You will regret not using a relay, fuse, and large guage wiring, I promise you that.

Practically speaking: Using the stock horn wiring you will not get all the aftermarket horn volume you paid for. The stock wiring will definitely reduce sound.

Technically speaking: You probably won't melt the factory wiring if you use the horn in a 'normal' fashion. The occasional toot-toot won't damage wiring whereas a good long angry hhhooonnnkkkkkk...... will heat up the connectors and the wiring. Lotsa tootin' will eventually get to the horn switch.

Finally, if the horns were as loud as they could be, you probably wouldn’t need a protracted honk FJRandy gives good advice!

Alan

Haven't done the horn thing yet, but this I do know from years of owning Yamahahas-their switches cook easily, and sometimes, spectacularly. I have repaired some, but often once cooked, they're history. Take the advice.

When I originally wrote up the Man-Horn article in 2003: FJRTech: Installing MAGNUM BLASTER electric horns, I spec'ed out premium 12-gauge wire and the use of a heavy-duty relay for a reason.

Use the relay, 'bro. Trust me.

Thanks Warchild.

I DO include a slightly modified version of your wiring diagram with my harnesses.

It's just modified to show the layout of the harness, otherwise your diagram is spot on!

Just letting you know.

And thanks to everyone else who at least understands why you shouuld use SOME type of external power for the horns.

Randy

Yep, a little redundant here. Buy Randy's harness, nice and easy lemon squezy. Did i mention that the MB's are fricken loud?

I almost look for a reason to use them. haha

Randy, figure up anything on the nautlis air horns yet?

mo

Well, I really hate to create any enemies here, especially in light of you esteemed people who have given so much to this community. I also appreciate your taking the time to add your comments.

But nonetheless, physics are physics and opinions aren't. Everyone is entitled to their opinions - I make no qualms. It is just that I prefer a scientific approach to these problems.

So I took some measurements:

Fuse +12V to horn +12V impedance: 0.1 ohms

Battery GND to GND term (after adjusting for horn's internal) impedance, with horn switch closed: 0.2 ohms.

Using ohms law, E = I * R, then the voltage drop across both directions for a single horn is 1.8 V. At a 14 V input (alternator voltage), that means the horns get 12.2V.

I also tested the actual voltage across the horn during activation. With a battery voltage at 12.3V, the voltage across the horns was 10.6V. Essentially as I calculated above, a 1.7V drop.

The power disappated by the wires per horn in total, according to the power equation: P = E * I, is 10.2 watts, a total loss of ~21 watts.

Now, checking the Handbook of Electronic Tables and Formulas, you will find that 18 gauge wire can handle a maximum current of 16A. This assumes a conservative estimate of wire in open air at nominal temperature (neither of which is that of the wires in the bike however).

Here is a site (Click me) which has a convenient calculator. Entering 18 gauge copper, 12 V, a conservative 6 feet (total for 3 feet each way), and 12A, it calculates to be 1.1 V drop, therfore an ending voltage at 10.9 V. Putting in 20 gauge leads to what I calculated above at 1.8 V.

So, agreed, this is right on the fence. There is still no way to know if the switch can handle the current, but I am willing to give it a run. Worse comes to worse, I wear out the switch and replace it. But I am not crazy about $115 to replace it, so maybe I'll just add the relay in the location I stated above (I will likely go that route).

Most importantly is performance. I am going to hardwire the horns to the battery and compare the sound level to that of the stock wiring. If there is a perceptable difference, then I will make an adjustment.

FJRandy, you are sounding defensive but I am not making any claims that your product offering is not good. I think you have done a great job and are providing a great service. You have made it very easy for people to upgrade their horns and you are to be commended. However, your information is not accurate. The stock wiring will not "fry" and it will certainly not "take out the others". The voltage drop is 15%, so the efficiency is a more likely 85%, not 60%. There is no "quick burst" of current - these are steady current devices and do not have a start up surge.

Thanks again everyone, I will let you know more as I work through this.

-BD

DB

You forgot the theroy of "Lady Luck"...and the ever popular but never the less tried and tested "If something can go wrong it will go wrong"

And please FJRandy sounding defensive??? I'm not his keeper he is quite capable of doing his own thing but really sounding defensive...fuck off!

BrunDog,

for all I know your calculations may be right.

But it took me all of half a minute to order my harness from FJRandy, got outstanding service and follow up (beside a professionally made harness, of course) and the ensuing peace of mind.

Management types :boss: would call it a "make or buy" decision and I had no doubt. Buy.

But if doing all the calculations and proving your theory floats your boat (or honks your horn as the case may be ) more power to you bro. unk:

Stef

BD, you have proven to your satisfaction that you don't need heavier wires or relay so go for it :good: Horn switch welding is not addressed.

By the electrical calculations you used, your evaluation is correct. [by the numbers a bumble-bee doesn't fly ] There are still some audio evaluations and calculations that could/should be used. In this 'Blaster Debate everyone posting here is correct so this comes down to personal choice.

In the following I am not trying to convince or befuddle anyone, just putting more info on the table:

================================

The power dissipated by the wires per horn in total, according to the power equation: P = E * I, is 10.2 watts, a total loss of ~21 watts.

Click to expand...

A 21 watt drop is lotsa watts! Turn on a 20 watt light bulb, let it run for ~ 5 minutes then go over and grab the bulb... blisters? A bulb has ~9 sq/in of surface area in which to dissipate heat yet it still gets darn hot (care to take a guess at how many sq/in of surface the wire run has?).

Audio output is logarithmic not linear, sound output level does not follow watts driving the coil linearly. Even if the wires will technically carry the current you are not getting all the sound you paid for with the Magnums.

Connector contact is typically where most power gets dissipated. You will typically find melted connectors long before finding melted wires. If a wire has melted insulation it will typically be close to a terminal.

Mister Wizard time: Often a car stereo shop will have a dB meter for mapping audio systems. Using stock wiring and stock horn button, have them take a reading 10' away, ~45° angular. Install heavy wire harness and relay, try again. Report results back to the list. FJRandy, up to this?

Alan

RonBB --

Actually the horn current is an oscillating AC current. The horn has a switch contact in series with its electromagnet coil. When the electromagnet pushes the diaphragm inward the switch contact breaks the circuit allowing the coil to reset to its non-energized position. The switch contact is again closed in this position and the coil energizes again. This cycle repeats approximately 400 times a second or whatever the frequency the horn emits.

When you have two horns in parallel with slightly different frequencies the zero current intervals won't be as frequent but there'll be several each second.