Energy loss and efficiency

[Richard21]

Having experimented a lot with LEDs for home lighting, Ive concluded that often more energy is lost in stepping down voltage and current than actually lighting the LEDs. Both resistor and constant current circuits have to 'dissipate power' in order not to overdrive the LEDs. Worst case scenario. 1 luxeon LED running off 12 volts battery. My conclusion is that while LEDs are very efficient themselves, providing a power source other than from torch batteries is a wasteful exercise.

My goal is to have a complete home lighting system running off low voltage 12 volt accumulators, charged by solar/ wind power renewable sources. To do this, requires maximum power efficiency and minimal waste through step down and dissipation. The best Ive got is running 3 LEDs in series to get as close as possible to 12v, allowing for a CCR supply and fluctuations in charge/ discharge states of the batteries.

My question is, has anyone else 'invented this wheel' and can offer any advice in efficient drivers and methods of circuitry?

Thanks

 

[Long John]

Hello Richard

I created for my camp-mobile a Led-lamp. My thought was, deplete my Luxeon III's which I had left from my flashlight-mods (due to ermitter swaps to the next generation Cree's and SSC's).
The goal was, as efficient as possible.

My personal result looks this way:

Mounted on the ceiling and on:

Underexposed :

And the GID-effect:

I wired 4 ermitters in series without any resistor or driver. Since the batterie-current isn't constant (~11,8V-~14,2V) I used 4x Led's to be sure that the Led's will not get a "burn-out-syndrome"

Each ermitter gets between 350 - 500mA (depending on the batt.-current) and due to the "overbuild" heatsink, the lamp will last forever.:twothumbs

Of course, you can also use an efficient driver (take look at the Shoppe or George's nice drivers) with the possibility to have different brightness levels.

Good luck and best regards

_____
Tom

 

[Richard21]

Thanks Long John for a nice example of simple efficiency. I have been put off wiring too many LEDs and in your example, 11.8 volts will only supply 2.95 v Not enough forward voltage on a low battery? Anyway, Occam's razor suggests that the simplest solution is usually the best one., so I will probably adopt this idea of series sharing. It just means the supply voltage needs to be regulated a bit better. It seems a good idea to use 6v accumulators as there is less stepping down required, plus they can be banked together and tapped to get 6, 12, or 18v, depending on the size of LED arrays.