Having had a less than excellent experience with the high power LEDs in my bench floodlights, I though it might be interesting to remove the reflector and mount four 10W LEDs in parallel to create an effective 40 watt array, but just being run at a much more sensible 20W. That would also spread the thermal dissipation across a larger area on the heatsink.
To do this would require the version of the LED with the nine chips in series to give a combined forward voltage of around 27V. There are two types of these LEDs. The most common seems to use the three by three series parallel array with a forward voltage of around 9V at 900mA. This is the type favoured by naughty Chinese factories using a standard 3W driver to make a "10W" floodlight light up.
I've also been hearing good reports on the quality of stuff from Sure and have used them myself in the past with no problems. So by getting a pack of ten of these LEDs it would give me a chance to do a test on them all for rogue LEDs with parasitic parallel resistance issues. (When random series LEDs are at different intensities at a given current.)
First notable thing was the packaging. The LEDs were wrapped in low static generating pink bubble-wrap and then shipped in proper metallised static shielding bags. This is kinda rare for a typical Chinese supplier and an indication that some care is being taken to protect what could be good components.
I tested them by lining them all up in a row and then setting my bench power supply to the threshold where the series string of 9 chips started passing current of about 1mA.
Placing the leads across each LED in turn showed all the series chips in each lighting at the same intensity at that current. Some whole LEDs were slightly dimmer, but that was most likely due to the use of a fixed voltage showing slight combined forward voltage variation.
I suppose another approach to the use of these LEDs in a 20W fixture is to put three or maybe even four of the 3x3 series parallel version of this LED in series.
Here's a link to the listing I bought these LEDs from.
http://www.ebay.co.uk/itm/380978942159
To do this would require the version of the LED with the nine chips in series to give a combined forward voltage of around 27V. There are two types of these LEDs. The most common seems to use the three by three series parallel array with a forward voltage of around 9V at 900mA. This is the type favoured by naughty Chinese factories using a standard 3W driver to make a "10W" floodlight light up.
I've also been hearing good reports on the quality of stuff from Sure and have used them myself in the past with no problems. So by getting a pack of ten of these LEDs it would give me a chance to do a test on them all for rogue LEDs with parasitic parallel resistance issues. (When random series LEDs are at different intensities at a given current.)
First notable thing was the packaging. The LEDs were wrapped in low static generating pink bubble-wrap and then shipped in proper metallised static shielding bags. This is kinda rare for a typical Chinese supplier and an indication that some care is being taken to protect what could be good components.
I tested them by lining them all up in a row and then setting my bench power supply to the threshold where the series string of 9 chips started passing current of about 1mA.
Placing the leads across each LED in turn showed all the series chips in each lighting at the same intensity at that current. Some whole LEDs were slightly dimmer, but that was most likely due to the use of a fixed voltage showing slight combined forward voltage variation.
I suppose another approach to the use of these LEDs in a 20W fixture is to put three or maybe even four of the 3x3 series parallel version of this LED in series.
Here's a link to the listing I bought these LEDs from.
http://www.ebay.co.uk/itm/380978942159
How can I tell what surface mount led wattage i need to replace in a head torch please
?
Cheers and thanks from Aotearoa NZ. Love the information.
Hi Mr. what is the maximum working temperature, that can be measured in the led heat sink , excuse my English and thanks!
Hey,I just got some 10W LED chips to build a custom night light.Is it possible to wire LED Chips in series or must they be in parallel?If there can be wired in series,does it mean that I need a 36V power source if one LED has a rated voltage of 12V?
WHAT IS YOUR THOUGHT ON USING THESE IN A CAP DROPER CIRCUT 5 OF THESE IN SEARIES I AM ON 120 VOLT @ 60HZ
I must say I enjoy all your videos, and rather enjoy the in depth break down of the items. Recently I converted all of my 4 foot shop lights over to leds using the 8520 rigid strips powered by 12 volt solar charged battery and they work great.Got the led bug so its now on to my next project. I have built a under water led drop light with 9 green 10 watt leds powered by a 12 volt automotive battery. this is where I have some concerns The leds are connected in parallel and their specs are, voltage DC 9-10.8V ,current 900mA and they have the integrated approach 3 and 3. I don't to destroy the leds and for some reason I just cant wrap my brain around how to power them, brain fade I guess. would you have any suggestions. keep up the great videos thanks.
Pink bubble wrap is not "static generating". The pink bubble wrap is anti-static. Honeywell ships replacement displays and components in it, many of which are ESD-sensitive.
what are their lumens output ? and how do they compare to say cree xm-l2 u2 10watt leds?
Clive, I got one of these a couple of years ago now with a matching power supply. Back when it was just Sure Electronics. I rebuilt a desk lamp with the set, with heat sink from an old PC. I've put at least five hours a night on that lamp and it hasn't let me down. They seem like they're very well made. They have nice audio amplifier circuits too.
I don't think you can assume that if you put 4 of these in parallel that 600mA will be equally shared among them. They don't present a resistive/linear load to the supply. If there is enough variation between individual units, you could very easily wind up with a much greater fraction of that 600mA going through one unit than through the others (right up until the moment when the one sinking the higher current fries, that is !).
short and sweet, feed me more! Have a good day.
I have been using sure electronics for many many years now and I am very happy with there service.
Nice video man, I have been thinking about building my own shop lights and I knew the larger COB's had issues or developed them as time goes on, these COBs seem to be a better solution and priced reasonably, I am not keen on the shipping time though, it would take about a month to get to me for some reason..