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builder in training
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Discussion Starter · #1 ·
hey everybody,
i am wiring up my bike and am not very versed in the whole electrical thing. I am not running a fuse box, just a main fuse, however on my stock fuse box the highest rated fuse was 15amps.

I am trying to decide what amperage switch for my "on/off" and i don't how many amps it will be getting. i found a switch that i want, but it is only rated for 10 amps at 12V DC.

I am running two in-line switches for my ignition (an obvious switch and a hidden switch) that are controlling the main power line off the battery that has an inline 30 amp fuse before either switch. So obviously if i get more than 30 amps the fuse will blow. however, is there a way to guesstimate how many amps i WILL be getting?

i guess the crux of the question is, can i get away running a 10 amp rated switch for my ignition or do i need something beefier. i dont want to melt anything.
 

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lɐʇuǝɯᴉɹǝdx&#4
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Depends what all is drawing current through that ignition switch. I'm guessing a hot (positive) wire runs to the switch and from there to various devices (all fused) and then to ground? In that case, just add up the amps for the fuses, that's the max that would ever be pulled through the switch. I'm guessing that's more than 10...

You could get some load off the switch by running straight to the (fuse for) certain items. I re-wired my bike so that the headlight and radiator fan aren't going through the ignition switch, for example; there's just a straight shot (through a 30 amp fuse) from the battery to their (5 & 10 amp) fuses, and you can turn them on when the bike is parked just by flipping the switches. I did that mostly to simplify the wiring (there was some complicated jiggery pokey that shut them off when the starter was powered, and my starter switch needed replacing) but it has the side effect of reducing the current through the keyed switch.

Alternately, you can reduce the switch load by running some of those items on relays, so that the amps on the original circuit (and thus the switch) drop to a minimal amount, because the actual power is coming straight (through a fuse) from the battery on the relay circuit.

Sorry if that's not really clear... I picked up wiring from my dad when I was maybe 7, and never really learned the technical terms, just kinda wing it. Its been enough to let me do anything from bikes up to tapping 3 phase transformers for my welding shop, though!

TLDR- Since the crux is really the ignition, you'd have to look at what the amps of the fuse for the ignition (plus whatever else is switched) is. Usually the ignition alone has a 10 amp fuse, so I wouldn't want any other load on that switch. I'd either find a beefier switch, or shunt everything else off onto independent circuits or relays. If you don't, you might be OK, or you might end up using the switch as a fuse when your 10 amp fuse pulls 9 amps and a 5 amp fuse pulls 4 (individually safe, but combines to 13 amps...)

As a general rule, you should have a fuse "upstream" of any switch (or device) that has the same / lower capacity as the switch (or device). Hooking that 10 amp switch right up to a 30 amp fuse isn't safe; if the wire coming out of the switch shorts and passes 20 amps, the fuse won't blow, but the switch could go up in flames. Fuses should be weaker than anything the feed.
Instead, the 10 amp switch should be pulling its juice through a 10 amp fuse (which could be downsteam of the 30, or direct from the battery pos). Then you don't really have to worry about what you put on the switch nearly as much. Could be multiple items totaling more than 10 amps, but which aren't ever run at the same time to reach a total over 10. Worst case scenario is you blow that 10 amp fuse if you accidentally run to many at once or some of them short, but that's what that fuse is for, and the switch / wiring (and user) will be safe!

Gimme a day or so, I'll get a picture of the backside of my "accessory fuse block" up, you'll see what the method in my madness was. Something similar might work for you.
 

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builder in training
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Discussion Starter · #3 ·
Depends what all is drawing current through that ignition switch. I'm guessing a hot (positive) wire runs to the switch and from there to various devices (all fused) and then to ground? In that case, just add up the amps for the fuses, that's the max that would ever be pulled through the switch. I'm guessing that's more than 10...

You could get some load off the switch by running straight to the (fuse for) certain items. I re-wired my bike so that the headlight and radiator fan aren't going through the ignition switch, for example; there's just a straight shot (through a 30 amp fuse) from the battery to their (5 & 10 amp) fuses, and you can turn them on when the bike is parked just by flipping the switches. I did that mostly to simplify the wiring (there was some complicated jiggery pokey that shut them off when the starter was powered, and my starter switch needed replacing) but it has the side effect of reducing the current through the keyed switch.

Alternately, you can reduce the switch load by running some of those items on relays, so that the amps on the original circuit (and thus the switch) drop to a minimal amount, because the actual power is coming straight (through a fuse) from the battery on the relay circuit.

Sorry if that's not really clear... I picked up wiring from my dad when I was maybe 7, and never really learned the technical terms, just kinda wing it. Its been enough to let me do anything from bikes up to tapping 3 phase transformers for my welding shop, though!

TLDR- Since the crux is really the ignition, you'd have to look at what the amps of the fuse for the ignition (plus whatever else is switched) is. Usually the ignition alone has a 10 amp fuse, so I wouldn't want any other load on that switch. I'd either find a beefier switch, or shunt everything else off onto independent circuits or relays. If you don't, you might be OK, or you might end up using the switch as a fuse when your 10 amp fuse pulls 9 amps and a 5 amp fuse pulls 4 (individually safe, but combines to 13 amps...)

As a general rule, you should have a fuse "upstream" of any switch (or device) that has the same / lower capacity as the switch (or device). Hooking that 10 amp switch right up to a 30 amp fuse isn't safe; if the wire coming out of the switch shorts and passes 20 amps, the fuse won't blow, but the switch could go up in flames. Fuses should be weaker than anything the feed.
Instead, the 10 amp switch should be pulling its juice through a 10 amp fuse (which could be downsteam of the 30, or direct from the battery pos). Then you don't really have to worry about what you put on the switch nearly as much. Could be multiple items totaling more than 10 amps, but which aren't ever run at the same time to reach a total over 10. Worst case scenario is you blow that 10 amp fuse if you accidentally run to many at once or some of them short, but that's what that fuse is for, and the switch / wiring (and user) will be safe!

Gimme a day or so, I'll get a picture of the backside of my "accessory fuse block" up, you'll see what the method in my madness was. Something similar might work for you.
this was veryhelpful and i dont know the technical terms either so i followed just fine. I had the same type of tutoring when i was about 12 but not my dad.

the crux of what i got from your post was, the simple solution is not to use that switch. which is okay. i have some really simple 35 amp toggles that i was going to use. For simplicity's sake i am not running a separate fuse box. all i am powering is the coils, lights and gauge. the tail light and turn signals and gauge are LED so that is almost no draw at all. however between the headlight and the coils i will def be over 10 amps. so i will just use a decent switch.

here is a different question... is it worth the trouble of wiring in a 4 circuit fuse box? (the stock bike was 4) because that would almost double the amount of wires on the bike. So i dont know if it is worth it.

thoughts?
 

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GURU of da poo poo
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The fuse box will be nice if anything shorts out or you have any issues in the future.
 

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lɐʇuǝɯᴉɹǝdx&#4
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Ah, if yer not wedded to the 10 amp switch, then yeah, running a 35 amp switch off a 30 amp fuse is a great idea.

I do not think running everything through one 30 amp fuse is a good idea; I'd do the fuse box with 4 fuses. You want your fuses to be the weak point in the link of any (sub) system, and having one big central fuse goes against that principle. If the lights short out, you don't want there to potentially be 30 amps going through the wiring for the lights, because that (typically 16 gauge) wiring is not up to handling 30 amps, nor are your handlbar switches, etc; that stuff could be damaged before the fuse blows. Or worse, the fuse might not ever blow if the resistance of the hot wiring and fried switches is enough to keep the current below 30 amps. Hence, you want box with a 5 amp fuse for your lights (assuming 55 watts), 10 for the coils, and maybe another 5 for the signals and gauge. And that hangs off the 30 amp fuse, because the box itself might short. Not sure on the specifics, but I'd also expect the charging system / voltage regulator and related wiring should get some protection against shorting.

Fuse boxes are actually really handy ways to break out & centralize wiring, with all those built in connectors they have. I don't see how using one increases the number of wires much, and certainly not doubles. The do tend to be bulky though; you could do it all with inline fuses if that's a problem.
 

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ingamaneer
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Fuses keep your wires from going up in smoke. I would shy away from sticking one big fuse in the system, with no branch fusing.


For the switch, as others have said, use a relay. Use the switch to turn on the relay. The relay contacts (40A are common) will handle the amp draw of the system.
 

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Is my bike ok?
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Just a friendly FYI :you can't push amps, they can only be pulled. So, if you were to have a 30 amp short to ground it will not "zap" everything on your bike. Only whatever point that wire touched ground out.

But yes, 30 amps will murder basically any wiring on your bike. Anything under 10 GA.

Fuses are good. Cheap. And much easier to replace than any wiring.
 

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I'm an industrial electrician and work with big stuff like overhead cranes and HV motors so that probably influences how I'd do things but what I'd do is:

Battery positive through the normally open contacts of a 12v relay
Relay coil wired to an ignition switched positive
output side of relay to the fusebox
Split your circuits down however you see fit.
headlights, indicators + brakelight + horn, igniton, accesories perhaps?
size all fuses accordingly

Edit: forgot to mention, add up the power of all your electronics and divide by 12, that's your max draw in amps so make sure your relay is rated to that (or at least nearly, you won't have your high beam, all indicators, horn, and brake light on all at once really so a couple of amps below will be ok - this is in the electrical regs and called discrimination so its safe to do)
 

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lɐʇuǝɯᴉɹǝdx&#4
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For mine (was a 6 fuse holder) I ran some heavy gauge copper through all the connectors on one side and soldered it to them, then painted over the whole side with liquid e-tape. A 10 gauge wire from the battery comes in on one end, where I have a 30 amp fuse. That means I get (30 amp fused) power to every other holder in the block, and I just put in fuses and pull wires off the open connectors as needed.

Potentially there's the risk my 10 gauge wire might short to the frame somewhere between the battery and the fuse block, but at some point you gotta put faith in stuff to not just fall apart, eh?
 

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builder in training
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Discussion Starter · #11 ·
I'm an industrial electrician and work with big stuff like overhead cranes and HV motors so that probably influences how I'd do things but what I'd do is:

Battery positive through the normally open contacts of a 12v relay
Relay coil wired to an ignition switched positive
output side of relay to the fusebox
Split your circuits down however you see fit.
headlights, indicators + brakelight + horn, igniton, accesories perhaps?
size all fuses accordingly

Edit: forgot to mention, add up the power of all your electronics and divide by 12, that's your max draw in amps so make sure your relay is rated to that (or at least nearly, you won't have your high beam, all indicators, horn, and brake light on all at once really so a couple of amps below will be ok - this is in the electrical regs and called discrimination so its safe to do)
okay,
this will completely show my ignorance of wiring, however, why a relay? And how do i know which one to get? also do i just solder the wires to the relay and then use a connector or do i need some sort of holder like for a blade fuse?


is there a way to wire it up without the relay or is that necessary?

(edit) i can read wiring diagrams just fine, but coming up with wiring on my own is difficult, so all your help has been (and will be) VERY helpful.
thanks
~Chris
 

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lɐʇuǝɯᴉɹǝdx&#4
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The relay would make it so the fuse block only gets power when the ignition is on. It would need to handle all the amps that would get pulled through it. Its there so you can't leave your headlights (and other stuff) on with the key removed from ignition. Which happened to me yesterday. I ran out of gas in the center median, rushour, downtowd, froggered across the highway, walked to the station to buy a can and some gas, froggered back, and found out my battery was dead. (At which point a cop pulled up and gave me a jump.)

The order would go something like battery pos > 30 amp fuse > 30 amp relay (switched by key / ignition, which needs its own independent power circuit because it can't go on fuse block for obvious reasons) > fuse block with 30 amp total fuses > whatever items need power (keeping switches on positive side of items) > battery neg

That way, they key effectively "turns on" the fuse block.
 

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Forgot about this!
I'll reply properly later but the relay is there because your ignition isn't designed to handle big currents. You could use a higher rated switch instead but then someone else could turn it on and kill the battery. The relay is like an electrical switch that turns on when the ignition is on.

Gimme a list of what you're running on the bike and I'll come up with something
 

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builder in training
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Discussion Starter · #16 ·
Forgot about this!
I'll reply properly later but the relay is there because your ignition isn't designed to handle big currents. You could use a higher rated switch instead but then someone else could turn it on and kill the battery. The relay is like an electrical switch that turns on when the ignition is on.

Gimme a list of what you're running on the bike and I'll come up with something
i am not using a stock keyed ignition. i am using two inline 35 amp toggles that both have to be on for the bike to be on. as far as what else i am running;

Ignitor box
Left control (CBR600RR) turn signals, horn, high/low beam
Right control (09 R1) Kill switch, starter button,
headlight H4 bulb
LED turn signals (resistors included), and tail-light
Koso Gauge

I got a 4 circuit fusebox.

thanks
~Chris
 

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ingamaneer
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The reason everyone is saying to use a relay is partially because you are severely limited on high amp switches. They are typically relatively big, ugly and cumbersome to switch.

By using a relay to do the "heavy lifting" you can use any sort of switch you can find. You could use an itty bitty maintained pushbutton that blends into your gauge cluster to turn on the whole system, by using it to switch the relay. You can also use itty bitty wires connected to your itty bitty switch that way.


If you are happy with your big, ugly switches, then you really don't need a relay.


One other benefit of a relay is you can shorten the wire length of your circuits. Instead of all of the power having to flow from the battery, up to your switches, back to the fuse block and then onto the devices, you can put the relay down by the battery so its a shorter run. The longer you run your wires the heavier they need to be. (although I doubt you will have a long enough circuit to notice any voltage drop with reasonable size wire on a bike)

Relays with multiple internal connections can also let you do things like have the starter disable the headlight so you get full juice for cranking. This is often built into the start switch on many bikes, but its (again) much more robust if you use a relay to do that switching.
 

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Daytona has sorted relay definition very nicely and no need for me to input on that now

I'll try and draw up.something later at work if its quiet, probably not though as all the cranes have been breaking down all damn week!
Personally I run my koso on a single in line fuse for perma pos and take the ignition positive from the loom side of the starter button.
 

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builder in training
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Discussion Starter · #19 ·
The reason everyone is saying to use a relay is partially because you are severely limited on high amp switches. They are typically relatively big, ugly and cumbersome to switch.

By using a relay to do the "heavy lifting" you can use any sort of switch you can find. You could use an itty bitty maintained pushbutton that blends into your gauge cluster to turn on the whole system, by using it to switch the relay. You can also use itty bitty wires connected to your itty bitty switch that way.


If you are happy with your big, ugly switches, then you really don't need a relay.


One other benefit of a relay is you can shorten the wire length of your circuits. Instead of all of the power having to flow from the battery, up to your switches, back to the fuse block and then onto the devices, you can put the relay down by the battery so its a shorter run. The longer you run your wires the heavier they need to be. (although I doubt you will have a long enough circuit to notice any voltage drop with reasonable size wire on a bike)

Relays with multiple internal connections can also let you do things like have the starter disable the headlight so you get full juice for cranking. This is often built into the start switch on many bikes, but its (again) much more robust if you use a relay to do that switching.
well to be perfectly honest, this is by far the best explication i have ever seen on the subject. and you have convinced me. i would like to be able to run one ugly switch, as it will need a long throw and be up under the fuel tank in the frame (great... now you can steal my bike) however i would like to run that fancy shmancy switch near the gauge. and the ideal of the shortened wiring is a nice thought.

is there a particular relay i should get? And how should i wire it up?

thanks again for this wonderful explanation!
~Chris
 

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I've done a good chunk of your wiring diagram, will try and upload it at home later on.

Have no idea about your CDI box and your specific KOSO though.

I've done you a full lighting diagram, and the relayed ignition switching.


Its set up as lights, horn, koso and ignition on the fusebox, assuming you gave an ignition relay with an onboard 30A fuse?


I'll double check in my zzr 600 wiring diagram for where to put the killswitch in too as I'm not 100%
 
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