- First Name
- Donald
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- May 21, 2022
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- South Bend, IN
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- #1
I bought some Nite Light led lights advertised at 60 watts each. Putting two of these on a 10 A AUX switch worried me. Using conventional calculations (60 watts divided by 12 volts equals 5 amps each, times 2 lights equals 10 amps, or on the verge of blowing the 10 A fuse). So, I thought I’d measure the actual amperage draw.
With a 30A gage, I connected a 12 volt li-ion battery (actually at 13.5 V) up to one of the lights. I expected The gage to read at least 5A. With the light burning bright, the needle barely moved. I thought the gage was bad. So I hooked the battery up to a 2 ohm power resistor. Wala, the gage reads about 6A. Using V= A x R, it checked out. And using watts = V x R, the power usage was 72 watts.
I flunked the new math, so I thought I’d check another way. I replaced the power resistor with the light and in-line fuses, starting at 5A. I got all the way down to a 1/2A fuse before it started to glow, but did not burn out. So, here’s a lesson in new math.
P (watts) for LEDS is V x A x 10. So if a vendor is selling a LED rated at 600 watts, then the current draw will be 5A at 12v. So, your 10A Aux switches should handle a LED light rated by the manufacturer at 1200 watts.
Sounds like watt inflation to me. Or new math,. Or magic LEDS. Comments.?
With a 30A gage, I connected a 12 volt li-ion battery (actually at 13.5 V) up to one of the lights. I expected The gage to read at least 5A. With the light burning bright, the needle barely moved. I thought the gage was bad. So I hooked the battery up to a 2 ohm power resistor. Wala, the gage reads about 6A. Using V= A x R, it checked out. And using watts = V x R, the power usage was 72 watts.
I flunked the new math, so I thought I’d check another way. I replaced the power resistor with the light and in-line fuses, starting at 5A. I got all the way down to a 1/2A fuse before it started to glow, but did not burn out. So, here’s a lesson in new math.
P (watts) for LEDS is V x A x 10. So if a vendor is selling a LED rated at 600 watts, then the current draw will be 5A at 12v. So, your 10A Aux switches should handle a LED light rated by the manufacturer at 1200 watts.
Sounds like watt inflation to me. Or new math,. Or magic LEDS. Comments.?
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