I bought this 12V 10W LED floodlight to see if it used a current regulator or just a simple resistor. It turned out to use a current regulator based on a common CL6807 1A chip designed for use with LEDs.
I wondered if it was possible to use just a resistor to run a typical 3×3 10W LED directly on a 12V supply. Note that the resistor value I chose is only suitable for LEDs with a matching forward voltage. It would not be suitable for lower voltage LEDs.
Using a resistor also allows you to tweak the floodlight to run at much lower power like 5W for longer battery life and also much longer LED life. You could even add a switch to select between a high and low intensity mode.
Typical standard resistor values might be 3.3 ohm, 4.7 ohm, 5.6ohm, 6.8ohm or others. I’d suggest using 5W resistors to help with dissipation and also to make it easier to stick them to the case with a high temperature adhesive like silicone.
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