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Wattage of LED panels
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Posted by colokid 5/Colo (My Page) on Wed, Jan 21, 09 at 17:50
Not being a trusting soul, I got out my meters and did a little measuring. On a panel advertised as about 13 watts with 225 bulbs I measure about 7MA per bulb. Strings of 25 are running at about 50 volts. Thats some where 3 or 4 watts total.
On a panel sold as about 48 watts, I get 46MA per bulb. String of 28 bulbs at about 65 volts. Total of 112 bulbs. Some where around 10 watts total to the LEDs.
Seems to me these panels are about one forth of advertised. Could they be advertising them bases on the LED rated wattage, then running them way lower?
BTW, I am having good luck growing with them.
Kenny |
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RE: Wattage of LED panels
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*************
On a panel advertised as about 13 watts with 225 bulbs I measure about 7MA per bulb.
************* Did you buy a European model ? Because with that many led you need 220v to drive them.
Looks like it's using a half bridge rectifier so even if it's plugged into a 220v you only get half of them on at the same time.
So you only get 6.5 watts effective but the total amount of led would be 13 watts.
With 220v you would get about 0.03 A which is correct for these types of led (I assume these are red led at ~1.9 volts) |
another possibility
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| if it's a purple light American model running on 120v you would have about 64 led for red and about 44 led for blue. So with a half bridge rectifier would have 64 red led and 44 blue on at the same half cycle and the other 64 red led and 44 blue on at the other half cycle.
In any case would still only get about 6.5 watts effective lighting so yeah 13 watts is a ripoff. |
RE: Wattage of LED panels
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Power supply is a full wave rectifier (with cap filter) that has a limit set by capacitor/resistor. 48 watt unit has some kind of inductor too. Supposed to be the same for 110/220. All LEDs hooked up one way in strings and operate at about 60 volts. A constant current supply is hard to understand by a fellow that grew up with voltage regulated.
Sure would like to hook them up to a variable PS and crank them up. Wish I knew their current spec. of the LEDs are. Only way would to crank them up till they blew.
BTW, LEDs run on AC only get half cycle and much lower power as habman says. Rectified DC must be smoothed out with filter to get full power. Guess I could break out my ociliscope to measure but that would be a lot of work.
Think they just rate the unit by LED max rating, such as 100 1 watt LEDs would be called 100 watts when in truth it would run at about 50. Sure messes up comparisons with other light sources. |
RE: Wattage of LED panels
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