LED Light question - 30 watt from 85-265v ? - Page 1
Forum section: electronics / beginners

author: ez24
author_rank: Super Contributor
timestamp: April 11, 2018, 04:07:35 am
content: HiThe light has 85-265V stamped on it.I live in a 110v area and the light output from this light is less than a 18 watt LED spot light. Is this correct:110/265 = .42 so 42% of 30 = 12.5 The light looks like it could be a 12 watt bulb ??Here is the light:https://smile.amazon.com/gp/product/B007HZEJG2/ref=oh_aui_detailpage_o09_s00?ie=UTF8&th=1Under normal conditions what would a good reputable 100 watt LED light read on a Kill-A-Watt ? I assume it should read 100 and the rating includes the heat loss.This makes me think twice about Amazon reviews.TIA

author: james_s
author_rank: Super Contributor
timestamp: April 11, 2018, 05:15:35 am
content: I'm not sure what you're trying to say, where did you get .42 from? Your math is not making any sense at all to me. 85-265V is the input range from which it can operate, it will have a buck regulator in it to drive the LED so within that range the higher the input voltage, the less current it will draw.A 100W LED should read 100W on a Kill A Watt, assuming you actually mean a 100W LED and not an LED equivalent to a 100W incandescent lamp, which is going to be more like 18W.

author: Brumby
author_rank: Unknown
timestamp: April 11, 2018, 05:25:13 am
content: I can see where you got the 0.42 from - but that's not a correct calculation.Asjames_ssaid, that is the input voltage range within which the product will work. Same as a switchmode PSU.The actual current draw will depend on whether it is a true 100W LED - or if this figure is the "equivalent brightness to a 100W incandescent"Plug it into a Kill-a-watt and the numbers will tell you. Around 100W and it will be genuine 100W. Around 20W and it will be an "equivalent".From your observation of it being less bright than an 18W LED spot, I would think it's an "equivalent" rating.

author: ez24
author_rank: Super Contributor
timestamp: April 11, 2018, 05:27:20 am
content: Quote from: james_s on April 11, 2018, 05:15:35 amThe .42 comes from 265 volts (max input) divided by my voltage (110v). I am used to seeing either 110 or 220 controlled by a switch. This is the first time I have come across something with an input voltage of 85 to 265 volts. I am not talking about equivalent. I now wonder if the maker does.Thanks

author: Brumby
author_rank: Unknown
timestamp: April 11, 2018, 05:29:52 am
content: Quote from: ez24 on April 11, 2018, 05:27:20 amAre you sure?Any lightweight plug pack (wall wart) is likely an SMPS with a similar operating voltage range.

author: james_s
author_rank: Super Contributor
timestamp: April 11, 2018, 05:34:39 am
content: 85-265V auto-sensing stuff has been around for ages, laptop power supplies and mobile phone chargers have been that way for at least 15 years. Taking the max input voltage and dividing it by your line voltage to get .42 makes about as much sense as dividing the temperature outside by the age of your cat, you can do the math but the result of the calculation is completely meaningless.You can ignore the voltage range and just consider it a 120V bulb since that's the voltage you'll be using it on anyway. If you were to connect it to a 240V circuit it would draw half as much current as it does from 120V, the light output and power consumption will be the same.