RGB LED Strip current questions...

Forum 2005-2010 (read only) Hardware Interfacing
1

Hey all. Im building a circuit to control as many of these RGB Led strips as i can. here's a link to a VERY typical example of what you can get on ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150448686166

there are 12 leds per strip (thats about 1 an inch)

It is listed as having a power consumption of 1.8 Watt.

Here's my question(s)

1 ) is it safe to assume that the 1.8 Watt is when all 12 leds are fully light (RGB) or could that be per channel?

2 ) 1.8 Watts / 12 volts = .15 amps. The only way that seems reasonable to me, is when you think of it as 36 LEDs. Can someone make sure im sane on this?

3 ) what will be the current draw per channel? IS it really as simple as .15/3 ? because .05 amps to power 12 blue or green or red LEDs sounds a little bit low.

PS: i do not know if the leds are in series or parallel. i realize that knowing this makes it a lot easier :confused: I have every reason to believe that this strip is no different from all the other strips on ebay, and those strips look to be wired in series.

Please help me wrap my hear around all of this :confused:

2

If we assume that the 150mA is for a single color, that would be 37.5~50mA per LED (depending on whether it is wired as 3 groups of four or 4 groups of three LEDs).

I can confirm that is is wired as 4 groups of 3 LEDs... on one of the strips i got, there are 3 leds that do not light red... but do light green and blue.

That seems reasonable for "high brightness" LEDs.

True. And these are pretty bright..

So I would assume that the 1.8W/150mA number is for EACH color. If the 1.8W/150mA number was for all three colors, there would be very little power going through each LED, and they would hardly be "high brightness".

Well, that makes sense. I really wish they had provided me with even the sparsest of datasheets instead of trying to figure it all out this way:

Thanks for your time. Going forward, assuming that each color full brightness will take .15 amp is OK with the implementation(s) i have in mind.