LED garage lights - measurements

I made some measurements on my LED garage lights:

1N5406 Diodes +12.7V----[.5R]--->|--->|--->|--->|---+---[Module]---+ | | +---[Module]---+ | Gnd -------------------------------------------------+

I ran the lights for 2 hours before taking the measurements, to allow everything plenty of time to get up to temperature. The +12.7 (no load) supply drops to +12.3 under load. Current measured between the supply and the .5R was 778 mA. Voltage measured directly across one of the LED modules was 8.53 volts. So, that's 2 10 watt LED modules in parallel, running at ~6.64 watts total, or ~3.32 watts each.

I made a "light meter" from a solar cell battery powered path light by soldering 2 wires to the solar cell leads in parallel with the path light circuit, and connected a DMM to the wires. I set the path light on a box about 5' below the ceiling fluorescent. The positioning slightly favors the fluorescent over the ceiling LED modules. With the fluorescent on, I partially blocked the solar cell with a piece of cardboard until the path light just turned on. I then made measurements: ceiling fluorescent .094 volts (other lights off) ceiling LED modules .311 volts (other lights off) door LED modules .366 volts (other lights off)

In the measurements above, the path light connected to the solar cell always turned off when either the door mounted LEDs or the ceiling LEDs were turned on. The ceiling fluorescent was not bright enough to turn the path light off.

It's amazing that the 2 10 watt LED modules running at a total of ~6.4 watts outshine the 2 24" T12 Cool White (20 watt) fluorescent tubes. I used brand new tubes in the fixture for the tests to eliminate the possibility of aging affecting the results. I don't have specs on color temperature, only the subjective observation that it is about the same color for each source.

Ed

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