Author Topic: Farkle/Accessory Wiring Primer ( ST1100\ST1300 ) *  (Read 15357 times)

Offline KoTAOW

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Farkle/Accessory Wiring Primer ( ST1100\ST1300 ) *
« on: June 08, 2009, 07:19:31 PM »
This article written by Curt Gran, STOC #5137, IBA #330:
Curt is the owner of: fuzeblocks.com

~~~

Farkle/Accessory Wiring Primer

Part 1 of 5



I've been putting this off for too long but I thought I would start making some notes and posting my toughts on this subject. There's a lot of different options here and I want to stick to some of the most common ways. Then there's the different devices people want to hook up and how they want to hook it up. Some people want simple, some people want elegant, and some people want both. So this can be such a diverse topic that it's hard to include everything. This has come up so much though over the past month that I've decided I need to put some general stuff together to help people that want to get started.

Now DC voltage just isn't that tough. You have a positive voltage (12V typically) and you need a ground (anywhere on the frame will do or a ground wire somewhere on the wiring). When wiring plugs make sure that you have the postive terminal protector so when you disconnect it, it doesn't accidentally short against the frame and cause a short. A short is bad and a fuse helps protect that. Have the fuse as close to the power source (i.e the battery) makes sure that if you do have a short it will blow the fuse before it gets to the battery. If there's a short to ground on the positive terminal of the battery you're going to have a lot of sparks and a dead battery. A fuse blows when there's too much current run through it. That happens when you want to hook up a compressor to the accessory plug where the accessory plug has a 2 amp fuse but the compressor wants somewhere around 8 amps when it's working. You want a fuse to blow to protect a device and the battery.

Typically with a device you'll see the voltage it operates at and then they will give you the amount of power (watts) it consumes or the amount of current (amps) it draws. You might want to know the watts so you don't exceed the charging capability of the alternator on the bike or you may want to know the max current draw of a device if you are wiring your own harness and need to put a fuse in the line. The formula for figuring these things out is simple and is called Ohms Law. Here's a link to Ohm's law: Ohm's Law

Now there's a lot of formulas there and they represent volts with an E (for Energy I guess) but the formulas still hold. Typically we are operating with 12V but remember typically the voltage from the bike will be closer to 13 V. Voltage times Current (Amps) is Power (Watts) or E*I=P. Then there's P/E=I and P/I=E. You can use these to figure out the amount of current a device will draw and how much power it consumes when you know the voltage (12V-13V) and one of the other components (amps or watts).

There's other things to worry about like noise, grounding loops, shorts, opens, chaffing, etc. that need to be considered also but those are all things you have to learn as you go. All of this is some background but what you really want is a way to wire up your device to the bike.

First you need to consider how do you want to hook this up to the bike. Do you want to plug the power cord into a standard cigarette lighter plug or a powerlet (BMW) style plug. Or maybe you want to hard wire the cord into the bike somewhere.

The next consideration is usually whether you want the device to be on even when the bike is off or only on when the bike is on. This is usually refered to as constant or switched. Then there's the special exceptions where you may want it on in the accessory position also.

These first two considerations should take another into account and that is how many other devices do you plan on hooking up to the bike and what kind of power and hook ups are they going to require. Also how many will be in the front of the bike versus the back of the bike. Since running power wires from the front to the back or vice versa are a challenge to get right on the ST you may want to consider a power source located close to the device(s) you're hooking up.

Once you've taken these three things into consideration you're ready to start looking for resources to help you wire up your device. Now if you have the Honda accessory plug in the right fairing pocket and you have a device that plugs into a cigarette lighter then you're pretty much set and you probably never bothered looking at this primer. There's plug adaptors to go to the BMW/powerlet style plug if that's what you need also. So all you really need is a cable for your device and the plug you need to plug into the accessory plug. Wire the two plugs together and you're set.

There's a few places to mount plugs and they have all been covered in this forum on more than one occasion. There's the Honda accessory plug inthe right fairing pocket but you could mount one in the right pocket and also you could mount a BMW/powerlet style plug in either pocket also. Another place is to mount a BMW style plug on the fairing just below the right fairing pocket. There's even been a case where NormanPCN mounted one in the middle of the handlebars using the Honda plastic cover there. There is also a powerlet plate setup that will give you two powerlet plugs down by the rear shock adjustment knob.

If you don't have the Honda accessory plug you can have your dealer install it or install it yourself. It's not difficult but drilling a large hole in the fairing right pocket may be the piece that's hard to do. To install the accessory plug you will also need to install the quartet harness. What's that? The quartet harness is a wiring harness that plugs into a 9-pin mating connector on the left side of the bike and then fans out to 4 connectors. Some of those 4 are used for the accessory plug, the heated grips, and the radio (available only in the UK). There is an article on installing the quartet harness in the articles forum here and another article that has the full pinout on the quartet harness and all of it's plugs.

Now if you're still here you probably want to hardwire a device into your bike. Well know you have to think about the third consideration I mentioned before. If you are only going to wire this device and nothing else then you can worry about wiring your device straight to the nearest 12V source (switched or constant) and be done with it. However if you plan on possibly wiring something else in the future you may want to consider a fuseblock setup. Now usually if you can find a 12V source to plug into for one device you can use that spot to wire a fuseblock to and then put your one deivce on it and any others you add in the future. Again a fuseblock setup is optional if you just want to wire one device. There's another consideration here but it's less of an option and that is where you are going to install and use the device.

Positioning the device is usually predetermined by the device itself. If it's a something you need to access while riding it will probably be mounted in front of you on the handlebars or on the fairing (or a dash shelf). If it's lighting it may be out in front of the fairing. If it's heated clothing or brake lighting then it may be down by the seat, the frame, or back by the luggage rack somewhere. The reason for looking at this is that you need to pull power from somewhere and this can depend on where you are positioning the device on the bike. Obviously you can run wires anywhere you want but remember the longer the run the more issues you can have with pinch points and rubbing with can cause a wire to short or be cut/pinched by somehting.

There are basically 3 places that people get power from for wiring there farkles. One is from the battery itself. This is convienant for things that are mounted from the tank back. This is good for 12V constant but if you want switched 12V then you have to use a relay and make it yourself (more on this later). For the front and handlebars of the bike it's typically the quartet harness. The quartet harness provides switched and constant 12V. There are articles that cover the installation and pinout of the quartet harness in the articles section of this forum. The third place is off the fuseblock on the left side of the bike by using a fuse-tap device. This provides switched 12V. You will have to modify the rubber cap for the fuseblock though if you want to use this which is the reason I don't like it but it easy to do and convienant if you want swithced power with less hassle. Here's a link to Add-A-Circuit Mini.

If you're hooking up one device you just have to get your positive wire of your device to one of these places and get the ground wire to the nearest ground from that (even though any frame ground will do). Now if you're going to hook up more than one device then you want to consider a fuse block. There are some good fuse block choices out there and even a couple that you can do yourself. There's the universal one from www.electricalconnection.com. There's the 12 circuit BlueSea one. The AP-1 from Centech one is also very popular. If you don't like any of those then you can build your own using one from Buss that can be bought at most automotive parts stores. The one with the ground bus is preferred but you can do your own too.
« Last Edit: December 20, 2012, 10:10:09 AM by Tom Melnik »

Offline KoTAOW

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Re: Farkle/Accessory Wiring Primer ( ST1100\ST1300 )
« Reply #1 on: June 08, 2009, 07:20:05 PM »
Farkle/Accessory Wiring Primer

Part 2 of 5

Let's cover a little more on Ohm's Law and I'll try to create an analogy to help people understand basic DC electronics. There are 4 components to any DC circuit. I mentioned 3 before but I'll add a fourth here which is resistance. Any device, or wire for that matter, has some sort of resistance. Although we don't concern ourselves with it too much when wiring new devices it does come up as an issue when you have a corrodid connection because a connection that is corrodid creates more resistance meaning less juice for the device you're trying to power. So here's the four components:

(PIER)
Power (watts), symbol P
Current (amps), symbol I
Voltage (volts), symbol E
Resistance (ohms), symbol R

Why am I going over all this crap? I just want to wire up my stuff. How hard can it be? Well you can wire up your stuff with very little knowledge other than red wire positive and black wire ground. 90% of the time that is all you need to know. However things don't always go as planned and things fail. Why did I blow a fuse? Why won't the stupid thing turn on? Why do I smell smoke? Why did I bother getting out of bed today? This article is to help give you some background and basic troubleshooting because things are going to go wrong. The 4 basic components and some simple algebra is enough to arm you with what you need to do basic testing and troubleshooting. I may cover troubleshooting later but the basic rule is check the voltage before you plug it into your device. This means wire up the harness and apply power to it then measure it. You don't have a volt meter? Why are you reading this? If you are going to do ANY wiring go buy a simple multimeter. A multimeter can measure 3 of the 4 main components (IER). What about power? Power (watts) is derived by multiplying current (amps) times voltage (volts), P=I*E.

Here's a multimeter I keep on the bike. It's cheap but does the trick. The nice key features I like on this one is that it has auto shutoff, in case you forget to turn it off, and the leads are attached so there's no losing them.
Pocket Digital Multimeter

Now seems like a good time to present the two basic formulas to go along with the 4 components. These 4 components are all linearly related to each other in one way or another. With simple math you can derive the other formulas you need. With any 2 components you can calculate the other 2. Here's the two formulas:

P = I * E and E = I * R

That means that P/E = I and P/I = E, and E/I = R and E/R = I. Here's a simple example for the Garmin 2610. We know that the bike will produce somewhere between 12V - 13.8V. Typically you want to use 13.8V so you get the higher end of the device's operating range.

In the manual the Garmin 2610 can take 12-24V as an input but we know that the bike is typically outputting 13.8V under normal conditions. But they also state that the device generates 6 watts max at 13.8V. It's great that they give you this since not all device manuals will. We know the voltage and we know the power in watts so now what fuse do I use. I need the current. Current is I = P/E so I = 6W/13.8V = 0.435 Amps or 435mA. Now this is great in theory but if you ever actually measure the current draw on your Garmin you'll be hard pressed to ever see it pull a half amp (435mA ~500mA = .5A). I've tried to recreate this and I've never had it go over about 30mA so I have no idea where they get that value from but here's the issue. Go by what the manufacturer says since you should plan for worse case. The fuse that Garmin uses is a 1 Amp fuse. Why 1 Amp? Shouldn't it be something like a 1/2A fuse? Typically a device will handle a momentary increase in current but it is up to the design of the manufacturer. A device may recieve a voltage spike when starting up the bike with the device powered on. A good device will handle this without issue but again buyer beware. A rule of thumb would be a fuse twice the max current so in this case 1/2A * 2 = 1A. Now that is only a rule of thumb. If you want to be cautious and you have no idea what fuse the manufacturer used then calculate the max current and use a fuse just over that. Now you may blow the fuse and if you do you'll have to put in a slighty higher amperage fuse until you get one that doesn't. If you don't want to think about it just use the fuse that the manufacturer recommends and be done with it. Now if you do that and the fuse blows then you have issues and you need to resolve the issue. Putting in a higher amperage fuse at this point will only cause more damage to the device and possibly the bike. Either the postive lead on your cable harness is touching ground somewhere or the device itself has fried. You're going to have to figure it out. Without power applied to the cable harness and the cable unplugged from the device use a multimeter to measure the resistance between the positive terminal and the ground terminal. It should be almost infinite. If it's 0 or very close to 0 then you have a short in the cable somewhere and need to fix it. Again this depends on your power cable but if it's a straight wire to a 12V hookup then you have issues. Fix it.

On a bike you're usually concerned with the amount of power that all your farkles will consume. So use 13.8V for your 12V devices in your power calculations and all you need then is the amount of current that the manufacturer says the device will use. If they give you the power in watts for their device then great but if they don't and you can calculate it if you can get find the max current for the device. Usually the manufacturer is going to give you power or the current value. If not there are other ways to actually measure it with your multimeter but measuring current is not easy and is risky in some cases without more background (even I don't like doing it if I don't have to). Here's a device I keep around that can easily measure current but it's made for AC appliances so to adapt it to use on your farkles just get a DC adaptor.

Kill-A-Watt Meter

AC to DC Power Supply Adaptor (the black thing that the cellphone cord is plugged into)

With those two devices you can now plug in your device turn it on and the meter will tell you how many watts the device is using. Realize that devices use more power in different modes. Like the Garmin may use more power when it is trying to find sattelites. Your radar detector may use more power when it detects a signal. This is just a way to get a ballpark figure if you can't get it any other way plus it's nice to check your devices against what the manufacture tells you. Honestly most of the devices you're going to hook up to the bike are use so few watts that it just won't matter. The ST has a pretty beefy alternator. But for heated clothing/grips, or extra lighting (HID/Halogen) are things you want to know how much power they consume. With heated clothing/grips use a thermostat to control the amount of heat, and hence the amount of power, they consume. Manufacturers of high power devices will tell you the max power their devices consume.

Two things I need here: wattage output of the ST alternator and that chart someone had on how much the bike uses with no accessories.

Ok that's enough background. The next edition here will be back to wiring and adding a fuseblock as well as maybe a relay for switched power.

Offline KoTAOW

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Re: Farkle/Accessory Wiring Primer ( ST1100\ST1300 )
« Reply #2 on: June 08, 2009, 07:20:41 PM »
Farkle/Accessory Wiring Primer

Part 3 of 5

There's plenty of electrical information out there but sometimes you need to relate that information to the bike so that people here have a context to relate some of this to. I've been looking for a resource online that I can steal some basic information from, also to make sure I don't screw up what I'm saying, and I found one that seems to be pretty good:

http://www.the12volt.com/ohm/basics.asp

I pointed to the basics section that talks about resistors, diodes (which I may not cover), and relays. Relays is the next thing I want to cover. The relay example at the12volt.com is great but it starts talking about some of the terms like you know what they mean. Also to be complete they used a relay with one other contact than the relay that everyone typically uses on the bike that only has one contact circuit.

So maybe I'll give a crack at the relay thing. Why would I need a relay? A relay can provide you with a switched power source. Well doesn't the quartet harness have switched power? Yes, however maybe you need switched power at the rear of the bike or under the seat and running wires from the quartet harness back to those locations requires running wires past the coils or under the tank and frame which just creates points where the wire can pick up noise, get pinched, or rub against something over time and short out. Maybe you have a device that uses quite a bit of power and don't want it on the same circuit as your other devices that are hooked into the quartet harness. A good example here might be a that you want to add a set of PIAA's to the front of your STeed. You don't want to hook those types of lights to your quartet harness because of the amount of power they need to operate which may exceed the current limit of the circuit which is fused at 15 amps. Well you may say I'm not going to pull that kind of current so I can hook it up there. What you need to keep in mind is spikes when turning things on and off that may cause a fuse to blow even though the total current after the devices are running is less than the fuse rating for the circuit. Remember also that 15 Amps is the max you should pull through 18 gauge wire. If you constantly pull something close to 15 amps through that circuit you run the risk of frying the wiring also and that would be very expensive to replace. There are cases where you may be able to get away with it but to be safe just use a relay circuit. A relay circuit will allow you to get power from a solid source like the battery but unlike the battery it will be off when the bike is off. One of the hard parts about learning something new is terminology. Instead of explaining it all at once just makes it confusing because there's no context or background so this article may tend to ramble but it's because I'll explain terms as they come up so they are used in context.

Here's the basic relay that most people use for switched power on the bike:
30A/12V SPST Automotive Relay

Now this relay can handle up to 30A so that is going to handle just about anything you would want to wire through it on the bike. However you need to keep things like that in mind so you don't blindly wire everything you have through one relay. A good rule of thumb is keep your total current draw to half of the rating of the device. Back to the relay.

Wait, what does the SPST mean? Do I care? For the type of circuit we are talking about you really don't care but it stands for Single Pole Single Throw. What it means is that the relay can make one circuit (the pole, the switched circuit you're trying to make) and that it makes that circuit when the coil n the relay is powered (throw, meaning flip the switch on). That is the worst explanation known to man but basically use this type of relay and don't worry about it. There are multiple pole and mutliple throw types of relays but if you have a need for something like that then you're beyond the scope of this article and you should seek help from someone with more expierence in wiring. If you know you need a different relay then you probably wouldn't be reading this anyway. Anywho, the SPST relay is the simplest model and is easy to understand. Let's cover one other set of terms that are used to decribed the behavior of a relay.

The "normal" state of a relay is when the coil is not energized (for our example when the bike is off). So you will see terms used like "normally open" and "normally closed". These terms are referring to the state of the circuit that you are trying to make with the relay. Before I explain these terms remember that you have 12V hooked to a terminal on the relay and you want to "gate" that 12V to a device. That 12V you want to power your device with is hooked to one side of a contact on the relay via a terminal. The other side of that contact is hooked to the terminal that you want to wire to your device. When the contact in the relay is "closed" (the bike is on) that 12V is routed through the relay and out the other terminal to your device. When the contact is "open" (the bike is off) then the 12V to the contact side of the relay is not gated to the terminal that is wired to your device.

There are two sides to a relay and they essentially are physically seperated and can be thought of in that way when dealing with it. There is the coil side (it has two terminals) and there is the contact side (it has two terminals). To make it work you find a switched 12V from the bike (quartet harness, running light, etc.) and wire it to the coil side of the relay. The other side of the coil is wired to ground (the frame, a ground wire, etc.). That's it for the coil side. On the contact side you wire a constant 12V power source (the positive terminal of your battery) to one side of the contact and you wire the other side of the contact to your device that you want to power with the 12V that is hooked to the other side of the contact. The easiet way to understand this is that you have a switched source to the coil and a constant source to the contact. The voltage applied to the coil has nothing to do with the contact side of the relay and vice versa. The coil affects the operation of the contact but for all other intensive purposes they are electrically independent of each other.

A circuit refers to a completed connection (in our case 12V is applied to our device that we want powered with the bike is on). You have 12V from somewhere (your battery) that you want to get to somewhere else (your device) but only when the bike is on. A relay can make that happen by using a 12V source that comes on when the bike turns on to energize it's coil. When the coil inside the relay is energized it "closes" a set of contacts. One of those contacts is hooked to the terminal that comes from your 12V course (your battery) and the other contact is connected to a terminal that is wired to your device.

A relay is an electromechnical device, or in plain terms it's a electrical switch. You give it the juice (voltage to a coil inside the relay), a little lever moves inside it (you hear the click of a metal plate "closing" the contact), that lever makes a physical connection between two terminals on the relay (one of which has the 12V that you want to go to your device), and now the 12V from your power source is routed to your device through the two terminals that are now connected together by the metal plate inside the relay.

Here's an analogy to help you understand which 12V is which. Take turning on a lamp in your home. The wall switch is the relay, you are the 12V that energizes the relay, and the 120VAC is the 12V that powers your device. Now you don't have 120V AC running through you to power the lamp but you do have enough energy to flip the switch. So you flip the switch and now the 120VAC that is sitting at one terminal on the back of the wall switch is now gated through the wall switch and to the lamp. The only part of this analogy that doesn't work is that to make it comparible to the relay you have to hold the wall switch in the on position to keep the lamp on because if you let go the switch will turn off. What this means is that if the 12V that energizes the relay (you) is turned off (you let go of the switch) then the coil in the relay will deenergize (the switch flips to the off position). The coil pulls the metal plate away from the switched circuit side of the relay and your device is powered off (the lamp turns off). You know when I write this stuff I realize that some people are completely turned off by these explanations (HA! pun) but I'm hoping that the people who are intimidated by electical wiring will get some benefit out of it. People learn in different ways and as we get older we are more visual. You can't see electricity like you can a chain and sprocket so the only way to learn is to get a meter, get a relay, some wire and terminals and start playing with this stuff.

Well there's 4 terminals on the relay so what does what? I'm confused. Ok, slow down. One terminal is grounded, one terminal gets the switched 12V from the bike to energize the relay, one terminal is the constant 12V power source (probably from the battery), and the last terminal is the power wire to run to your device. That's it. The biggest challenge when you're face to face with the relay is trying to figure out which terminal is which. The documentation should come with the relay but even reading that may not be complete enough to get it.

continued...

Offline KoTAOW

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Re: Farkle/Accessory Wiring Primer ( ST1100\ST1300 )
« Reply #3 on: June 08, 2009, 07:21:22 PM »
Farkle/Accessory Wiring Primer

Part 4 of 5

In order for me to use the picture below I have to explain some more terminology.




Pretend that the 87a terminal is not there because the typically relay used and the one referred to above in this artcle doesn't have this terminal and for our application it isn't needed. If you want to know what it is, its the "normally closed" contact and it routes 12V to something when the bike is turned OFF (the relay coil is not energized) but NOT when the bike is turned ON (relay coil is energized). Now for the terminology lesson here.

The normal state of a relay is talking about the state of the relay when the coil is NOT energized. So a "normally closed" circuit means that the 12V source (the battery voltage) is applied to that terminal when the coil is not energized (the bike is off). In our case we need to use the "normally open" circuit (or terminal in this case). The "normally open" circuit is off when the bike is off and one when the bike is on. It may seem a little like reverse logic since the word "closed" implies that a circuit is made. However a relay, like the one shown, can have another contact (i.e. pole) that is connected to the power source terminal (from the battery) via the relay contact when the relay coil is not energized.

If you're trying to picture this in your head look at this picture:




So now we know our SPST relay is not used, or not working, in the "normal" state. In other words it does not have a "normally closed" contact (terminal) where 12V would be sent to when the relay's coil is not energized. Our relay only has a "normally open" circuit (terminal). The circuit is open (off) when the bike is off and is closed (on) when the bike is on. That my friends is the "normally open" circuit and it's the one we need to make all this work and it's the reason we ignore terminal 87a in the picture above. WOW! All that to explain why we're ignoring it. Bet you glad you didn't ask why. HA!

This was an extremely long explanation and I'm going to clean this up into a few sentences on the final draft but I have to say it a few different ways to figure out how I want to write it in the end.

Ok, honestly... I'll cover fuseblocks next. The reason I covered the relay first is that most installations of fuseblocks involve switched power and the relay is the way to accomplish that. So from the explanation the device we want to power is a fuseblock so that we can power multiple farkles when we turn the bike on (i.e. radar detector, low voltage lights, intercom, radio, etc.)

Of course if you have one high powered device to power then you can just use the relay and wire the switched terminal directly to your power source.

Now of course any device also needs a ground but the ground is wired to a ground source on the bike. The ground for your device is not run through the relay. Only the 12V for the device is sent through the relay. So your device has a power cord with two wires (one is 12V (positive), and the other is negative (ground)) and you better know which one is which. Typically devices will have a symbol near where the power connector plugs into the device that will show you which part of the plug is postive(+) and which is ground(-). For cylindrical plugs typically the center is (+) and the outside is ground(-). There's a reason for this. If you ever have the plug out of the device but there is power applied to the plug and you accidentally drop it against something else that's grounded (anything that is metal and is connected to the frame of the bike, another electrical device that you using like a troublelight for example that is connected to the ground through the AC plug, etc.) the negative part of the plug contacts the ground source instead of the postive part of the plug. This is another reason for a fuse to be located somewhere along the positive lead of your devices power cable. If that positive terminal accidentally touched a grounded source it creates a circuit from positive 12V on your bike directly to ground with 0 resistance. So what? Let's put this into perspective with Ohm's Law.

In this case we have 12V and 0 resistance or 0 Ohms. Now any fuse is rated in amps. It limits the maximum amount of current that can be pulled through that wire to your device. So let's see how much current is created when we have 12V and 0 resistance.

Current = Volts/Resistance or I = E/R

12V/0 Ohms = Infinity (or your computer says divide by 0 error)

So in this scenario by touching a positive lead on your device's power cable directly to a grounded source you have created a path of unlimited current. The amount of heat created by this type of situation will likely melt the wire if you power source is something as powerful as the battery on your bike. So how can I prevent myself from accidentally touching a positive terminal directly to ground. Well, you can be careful but the real answer is you can't. That's what the fuse is for. If you happen to do this, or if your device fails internally and creates a direct path to ground, the amount of current drawn will quickly exceed the maximum amount of current the fuse, that you wisely put on your positive wire, can handle and blow (or open). This essentially disconnects the positive lead from the battery and with no conection to the positive lead the current flow is stopped. Kind of like shutting off your water main because you just snapped the water supply pipe under the sink to your kitchen faucet. The faucet was the resistance. Without it the water is free to flow as fast as it can until another form of resistance is put into the circuit. In this case the water main shuts off the water flow. In our circuit it's the fuse that shuts off the current flow. So that's why you need a fuse.

There's one important point here to remember and that is the fuse is to protect the bike and the wiring on the bike. It's meant to protect the bike from you dropping the positive lead on a grounded source and it also protects the bike if you device fails and starts to draw too much current when the power plug is connected to your device. The fuse is not to protect your device. When you have the device plugged current has to flow to the device and then back to ground. So in order to blow the fuse the current has to have already flowed through the cable to the device. No typical automotive fuse (or practically priced fuse for that matter) is going to detect a sudden change in current fast enough to blow before it gets to your device. Fuses and circuit breakers in your house serve the same purpose. They are meant to keep you from burning your house down. They don't protect your precious Dancing Santa. If Dancing Santa shorts to ground and draws too much current he's fried and the circuit breaker blows breaking the circuit between 120VAC and ground. Santa is dead but at least you're not homeless. So if you think that circuit breaker on your power strip for your computer is protecting your computer think again. It's protecting your computer from burning down the house. Only a true "Surge Suppressor" or UPS will protect your stuff from a power surge and they cost more than $3 at Walmart.

I'm glad that came up because I felt like a lot of people don't understand that. Of course no one will get this far in the write up because they've already passed out from shear boredom. Too bad because their Dancing Santa is now burning down the house. Someone smell smoke?

Film at 11:00 along with fuseblocks. Really, I'm not kidding this time.

Offline KoTAOW

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Re: Farkle/Accessory Wiring Primer ( ST1100\ST1300 )
« Reply #4 on: June 08, 2009, 07:21:51 PM »
Farkle/Accessory Wiring Primer

Part 5 of 5

If you've read the relay crap above here's 2 pictures of relays that show their terminals. One is a 5-terminal relay that is SPDT (Single pole double throw) which can be used in place of the 4 terminal relay SPST (Single throw single throw) you just don't use the center "normally closed" terminal. But remember if you do that when the bike is off there is going to be 12V on that terminal so protect it that it doesn't short against anything else. You could wrap a spade terminal with tape and put it over that terminal. If you're anal like me, and unless you have a specific need for it, just buy the 4 terminal SPST relay.

5-Terminal SPDT Relay (this is the type of relay in the diagrams used in the previous post to show the internal workings of a relay. It has the 87a "normally closed" terminal in the middle) but it also has the same "normally open" terminal just like the 4-terminal relay.



The more commonly used relay for bike applications is the 4-terminal SPST (single pole single throw) relay that has only a "normally open" circuit.




If you're wondering what I'm talking about then apparently you missed the 40 pages of dribble I typed above.

One tip when you get your relay is to label each side of the relay with what the terminal on that side is used for. It doesn't have to be some standard labeling so long was you know what it is. This helps when you fasten to the bike some where and then go to hook up the wires. Use something permanent so it doesn't wipe off.
« Last Edit: December 20, 2012, 10:09:34 AM by Tom Melnik »