Good post, Sean.
But I'm unaware of any correlation between wattage [power consumption]
and candlepower [brightness].
Because different lights have different designs and efficiencies, it'd
be very difficult to say, "this light uses this many watts so it must
have this much candlepower."
Look at LEDs: they consume very little power but put off a heck of a
light. A friend of mine is experimenting with these lately, getting a
lot more light out of a bunch of LEDs than a single bulb, and using
less power. Also, the light tends to be more natural, more of a white,
rather than a yellow. [These are with white LEDs, of course.]
Trying to correlate wattage to candlepower is like saying because X
engine gets Y MPG, it must have Z horsepower. They just aren't related
like that, there are a lot more factors to it.
I'm not an electrical engineer, so this message may seem a bit naive,
but hopefully it helps, anyway. :)
-- Alek Benedict with a techno beat. [email] alek@earthling.net [web] http://members.sigecom.net/alek '93 Dodge Dakota Sport RC, SB, 2.5L, 5spd, 2x4, 3.55 '87 Mazda RX-7, NA 1.3L Rotary, 5spd [parting out due to blown engine] DML Profile: http://www.dakota-truck.net/profiles/dakota/MbY60Xj09WQIU/: -----Original Message----- : From: owner-dakota-truck@BUFFNET.NET : [mailto:owner-dakota-truck@BUFFNET.NET]On Behalf Of Sevrence, Sean : (S.J.) : Sent: Wednesday, April 11, 2001 10:02 AM : To: 'dakota-truck@BUFFNET.NET' : Subject: DML: RE: Wattage vs. candlepower? - Long response : : : Hey Jon! : : Hopefully I can get you back on track. I am consulting my physics book to : help us. : : Watts are a measure of energy. Candlepower is a measure of luminance (how : much light). You are trying to compare two different types of : measurements. : There is probably a correlation between the two, but I can not : find anything : here. : : Definition: Electrical power is the rate at which electrical energy is : produced or used. Electrical power is the product of the current in the : device and the fall of potential between its terminals. : : Watts are measured by the following formulas: : : 1) P=V*I where P=watts, V=volts, *=multiplied by, I=amps : 2) P=I^2*R where P=watts, I=amps, ^2=the value of amps squared, and : R=resistance measured in ohms (Ohms are the same measurement used for : speakers) : 3) P=V^2/R where P=watts, V=volts ^2=the value of volts squared, /=divided : by, R=resistance measured in ohms : : Definition: The luminous intensity of any other point source of light is : found by comparison. A point source for many purposes can be an ordinary : incandescent bulb if you are not too close to it. : : Amount of light is measured by: 1 candle = 1 candlepower - 0.981 cd : (candela). The SI unit system (metric) uses white hot molten platinum as 1 : cd. : : Candela is measured by placing a photocell above the standard source. The : standard source is then replaced by the unknown source. If the photocell : response is twice as large, we know the luminous intensity of the : unknown is : 2 cd. : : Most light sources have different luminous intensities in different : directions. For example, the photocell aimed at the end of a : light bulb will : read a different value than when aided at the side of the bulb. : These lights : you are considering are typically measured using an average of : the luminous : intensity in all directions, not just straight on. : : *** End of lecture *** : : What you need to verify is how fast these lights use the energy, how many : amps they use. The alternators are rated by how many amps they create. If : you use more amps than are produced, you will drain the battery : which is not : a good thing ;^P Once you know the amps of these lights, you will : be able to : size the wire to handle the total amount of amps for all of the lights you : want to use. Wire is rated by how much amperage it can handle : safely without : melting the insulation (very bad!!). You will probably want to run these : lamps to a separate fuse as well based on how much amps and how many you : want to run. : : Sorry for the long post all! I think this discussion warranted : it. It is not : a simple answer. HTH!!
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