Author Topic: Max watts through aux switch?  (Read 320 times)

dayday28129

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Max watts through aux switch?
« on: Sep 11, 2020, 02:14:15 am »
I want to add a light bar to my bike and it's my understanding I can just wire them straight into the aux switch wiring (in the headlight bucket). Does anyone know how many watts I can get away with for the lightbar? Do I need to add a fuse somewhere? Just don't want my bike melting to the ground.

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    sundancer87

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    Re: Max watts through aux switch?
    « Reply #1 on: Sep 11, 2020, 07:57:29 am »
    Wattage is not the factor for concern, it's the total amperage the light bar will consume.
    A relay wired to the switch would be a good way to go, along with the appropriate size fuse for safety.

    dayday28129

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    Re: Max watts through aux switch?
    « Reply #2 on: Sep 11, 2020, 05:33:19 pm »
    Wattage is not the factor for concern, it's the total amperage the light bar will consume.
    A relay wired to the switch would be a good way to go, along with the appropriate size fuse for safety.

    Wattage should be able to be used because it can be directly converted to amps. 120 watt light on a 12v system draws 10 amps right?. It is easier to find a light based on wattage than amp draw. Also, the bike should already have a relay and fuse for that switch because I believe it was set up from factory for the yamaha riding lights. From what I've read, the Yamaha driving lights put out a total of 70 watts, I just don't know if that's that max it can take and then on top of that I've had people tell me a lot of light bars marketed as "120w", the 120 is the incadesant light equivalent and it actually puts out like 21W.

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      StrykerBilly

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      Re: Max watts through aux switch?
      « Reply #3 on: Sep 15, 2020, 08:03:58 am »
      Wattage is not the factor for concern, it's the total amperage the light bar will consume.
      A relay wired to the switch would be a good way to go, along with the appropriate size fuse for safety.

      Wattage should be able to be used because it can be directly converted to amps. 120 watt light on a 12v system draws 10 amps right?. It is easier to find a light based on wattage than amp draw. Also, the bike should already have a relay and fuse for that switch because I believe it was set up from factory for the yamaha riding lights. From what I've read, the Yamaha driving lights put out a total of 70 watts, I just don't know if that's that max it can take and then on top of that I've had people tell me a lot of light bars marketed as "120w", the 120 is the incadesant light equivalent and it actually puts out like 21W.

      Yes, your calculations are correct(Ohms law again...)  If you find the fuse controlling this circuit you'll get the amperage.  You just need to be sure nothing else is on it as well(manual might say) but if so just add/subtract that in your calculations...

      Not the recommended way but you'll know pretty quick if you go over the circuit's amperage as the fuse will blow!!

      As someone already posted, if you need more power(say you have a really bright lightbar) you could use a relay and trigger that from the aux switch wiring.  If you go led you definitely won't need a relay as their power requirements are low...

      the urban legend

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      Re: Max watts through aux switch?
      « Reply #4 on: Sep 15, 2020, 08:30:07 pm »
      Yes, your calculations are correct(Ohms law again...)  If you find the fuse controlling this circuit you'll get the amperage.  You just need to be sure nothing else is on it as well(manual might say) but if so just add/subtract that in your calculations...

      Not the recommended way but you'll know pretty quick if you go over the circuit's amperage as the fuse will blow!!

      As someone already posted, if you need more power(say you have a really bright lightbar) you could use a relay and trigger that from the aux switch wiring.  If you go led you definitely won't need a relay as their power requirements are low...

      That switch is powered through the headlight fuse, in parallel to the headlight circuit.
      I'd rather die on a motorcycle than live without one.

      ,,