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How do you determine what size fuse to use when installing an accesory on a bike that does not have an inline fuse already?
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Keep putting them in until you find one that won't blow the first few seconds it is in.
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what is the fuse for?Comment
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And what is the volatge you are running, 12?Kan-O-Gixxer!
-89 Gixxer 1100 Engine
-Stage 3 Jet Kit / KNN Pod Filters
-Ohlins Susupension
-Various Other Mods
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You go based on two factors:
The size of the wiring used to the device, and the draw of the device itself (in amps, or if you only have watts, the formula is watts/volts = amps).
The fuse acts to protect the device, but often more importantly, it also acts to keep the wiring from acting as the fuse. To quote from my own upcoming book:
"Metal (wiring in this case) vibrates when electricity passes through it. Vibration always turns into heat over time (natural energy-state decay). The thicker the metal strand(s), the greater the heat sink to suck up extra heat, the more surface area to dissipate the heat, and the more dampening of vibration (by virtue of more mass), thus the more electricity it can carry without reaching a significantly raised temperature.
"All wires are rated for a specific current load at an ambient temp. Also note that automotive grade wiring uses multi-strand wires to handle flexing and road & engine vibration better, so this reduces the load capacity (the inherently higher temperatures around the engine compartment also reduce the effective rating).
"Fuses are, in essence, thinner wire (that will overheat & break earlier by virtue of it’s thinness), which is designed to give before the wire it’s protecting gets overheated. Thus, using higher-rated fuses effectively negates them, and makes the other wiring in the circuit act as the point of potential failure. Never use a fuse rated higher than the thinnest wiring that it protects."
Hope that helps make it more clear to you.
E.G. - If you're using a device which has a 48 watt draw (48 watts / 12 volts = 4 amps), it's drawing 4 amps. You should be using 18 AWG multi-stranded automotive-grade wiring (16 AWG for runs of over 10 feet), with a 5 amp fuse to protect it. The wiring I recommend is actually slightly thicker than "official" minimum requirements, but the recommendation is based on a combination of factors, including the temperatures it might be exposed to on the Katana (which can be quite high if it passes close to the engine compartment, exhaust, oil cooler, or the headlights).
Cheers
=-= The CyberPoetComment
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