Hi Everyone, I hope that you can give me some advice on this project. I am trying to make a switchable LED lamp head running off a sealed lead acid battery 12 v and 12Ah
I would like to have three channels of two LEDs on each channel. I propose to use the CREE XPGDWT-B1-0000-00LE1 chip (6 in total) as these seem to give High Lumens/watt. I need to have a duration of around 12hours with all three channels running. Please see Schematic attached. I have based this on the AL8805 current regulator chip. My questions are:
1 Does my Schematic look suitable?
2 The current regulating resistor (R1, 2, 3). Are they adequate to give me 12watts total power (2watts per LED)
3 How many Lumens could I expect total
4 How many Lumens/watt total

I hope this all makes sense and look forward to your comments

Thanks Colin

 

this seems a very complex way of going about things ... with a 12V supply why not use a 12V led? ....

If getting max lumens per watt is the main consideration Under drive the led/s they give 30% more light per watt if driven at about 25% max current .. will last much longer and won't need such a big heatsink if any ...

What is the light for , do you need a focused beam??

This is a typical led output curve ...Notice @ 0.6A luminance is 58 .... @2.4 A only 136

 

Hi OZ93666. Thanks for the reply. The lamp will be for wide angle use. Could I use the 11.9v XHP35 CREE LEDs and therefore do away with the voltage regulator? Would I still need the LED driver chips?