Doobying a cheap LED floodlight with lux/efficiency readings
Added: 10 days ago
This video is a continuation of an experiment that happened during a live stream on the BigCliveLive channel:-
During the stream I hooked capacitors in series with a cheap sealed 10W LED floodlight that is almost certainly baking its LEDs. This reduces intensity, but multiplies its lifespan significantly.
This time I used a light meter to get an indication of how the intensity changed with current, and got a rough approximation of "lux per watt" at a height of 300mm (12") from the front of the light. This was not an ideal testing scenario and is just for comparison on intensity.
One of the most notable things was how the efficiency dropped as the light heated up when running at full power. LEDs are less efficient at higher currents and when they are hot, so modern lights are not only designed to fail fast for profit reasons, but also perform badly as they do so.
Here are the results.
Full power cold 10.7W, 3010 lux, 281 lux per watt.
Full power hot 10.7W, 2800 lux, 261 lux per watt.
1uf, 3.8W, 1460 lux, 384 lux per watt. (Capacitor voltage drop 62V)
470nf, 1.9W, 840 lux, 442 lux per watt.
330nf, 1.5W, 640 lux, 426 lux per watt.
220nf, 1W, 450 lux, 450 lux per watt.
100nf, 0.5W (estimated), 210 lux, 420 lux per watt. (Capacitor voltage drop 90V)
47nf, 0.2W (estimated), 90 lux, 450 lux per watt.
22nf, 0.1W (estimated), 30 lux, 300 lux per watt.
At the lower levels the light's internal leakage shunt resistor would be affecting efficiency.
Even at reduced intensity the light output from a basic 10W light was very good. Useful for ambient or security lighting. At 2W and below it becomes viable to use it as a simple 24/7 light source.
It would have been nice to open this light, but it is glued shut with heat resistant silicone type adhesive. Previous attempts to open this style of construction have resulted in the glass breaking.
Some lights like this may contain an active buck regulator and will possibly strobe at lower power. But most seem to use the cheap linear regulators.
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