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So you want to run some accessories off of your motorcycle's power, but your bike doesn't have an accessory circuit or anywhere to plug things in? Here are some quick tips on how to do it.
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Signing UpStep 1Identify a circuit to use
Presumably your motorcycle doesn't have a dedicated accessory circuit, or you'd just be using that. So get a copy of your bike's wiring diagram and find a nice non-critical circuit (just in case we screw things up, we don't want to mess with something that'll stop the bike from running or that'll kill important safety equipment, like brake lights).
Make sure the circuit is suited to your power needs. The wattage that your accessories draw should be well below the power limit of the circuit. For example, if the circuit has a 5A fuse on it, make sure you are using considerably less than 12V * 5A = 60W. Keep in mind that you have to add up all of the draws (including the ones that were on the circuit before you start adding accessories). Don't cut it close. Don't replace the fuse to allow more current.
My bike has a circuit for a light that serves only to illuminate my license plate. Perfect!
After reading the wiring diagram, follow the colored wires to find the appropriate pair. Test to be sure it's the right circuit by unplugging it and seeing what turns off.
Make sure the circuit is suited to your power needs. The wattage that your accessories draw should be well below the power limit of the circuit. For example, if the circuit has a 5A fuse on it, make sure you are using considerably less than 12V * 5A = 60W. Keep in mind that you have to add up all of the draws (including the ones that were on the circuit before you start adding accessories). Don't cut it close. Don't replace the fuse to allow more current.
My bike has a circuit for a light that serves only to illuminate my license plate. Perfect!
After reading the wiring diagram, follow the colored wires to find the appropriate pair. Test to be sure it's the right circuit by unplugging it and seeing what turns off.
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http://www.instructables.com/id/Motorcycle-Accessory-Wiring/step1/Identify-a-circuit-to-use/
If you write up an Instructable on how to wire a circuit using a relay, I'd be happy to link to that as an example of what to do if you have larger power needs.
However, I don't think it's reasonable to say "you shouldn't connect any electrical equipment to your bike like this". I've had this setup going for years, powering GPS units and various electronics. I've never blown a fuse.
If you're doing something that blows the fuse every time you turn it on (or even occasionally) you should think long and hard about what you're doing. That should be a pretty clear sign that you're asking for more power than the circuit was designed to deliver. The "disaster" you're talking about is the result of ignoring that sign, not the result of wiring into a low power circuit.
I've a 1980 CB750-F Super Sport Honda, and I added some "fog lamps" the same way You did here.......and realized that It had an"accessory connector" hidden into It's guts (obviously, I found It when my job was done...)
Also, I noticed a little error in your first photo:
RED cable is for the positive , aka "power", or "+"
BLACK cable is for the negative, aka "ground" or "-"
Anyway, the instructable is clear enough to save our beloved electronics from death!
Normally, you do use red for power and black for ground, but that connector came with the colors reversed. That's why I put in reminders to test with a voltmeter and use colored heatshrink.
I've added a note to step 2, explaining the problem more explicitly. Does that make things clearer?
Thanks a lot for the info, red rider!