What can you do on a cold wet Bank Holiday Monday. Get the Soldering Iron out.

LED's are extremely efficient the actual power consumed for the light out is minimal.
The halogen bulb is more efficient than the common tungsten variety but the majority of power is converted to heat. So much so that the glass used has to be quartz and a special heat resisting glass cover has to be provided.

Naturally all is not perfect in LED technology. Once the LED turns on it will take as much current as the source can provide and destroy itself. A current limit resistor has to be provided, this resistor will dissipate power as heat. A lot less waste than a bulb but perfection aint there to be had.

Increase the supply Voltage and the resistor dissipates more power. there is no magic available, every means used to lower the voltage will involve power loss. In a 24 LED light we are losing about 2 Watts as heat getting about 0.5 Watt developing light.

I have removed 2 and added 5 resistors, plus 1 more diode in the 24 LED light. Single resistors rated at 0.5W are fine, each will create a hot spot in the plastic case. Using a higher wattage rating will spread the heat source, so will using 2 or more resistors in parallel.

Left hand model 1/2 Watt resistors. Right hand DISSIPATION.

converted

Electronics can be fun.
For lights which will run continuously for many hours the more the heat can be spread out the better. I just happen to have a bandoleer of 4.3K resistors which cost me nothing. There must be thousands of them, a life time supply.
Twenty three of those in parallel gives approx.180 Ohms. Nineteen gives approx.220 Ohms. One hundred and Eleven resistors instead of Five, ridiculous, well yes but 222 leads are all radiating the heat over a wide area. There is room for them in the battery holders, so why not. Expected failures, zero. The battery cover will have a few holes drilled for cooling air flow.