# lumencache lighting products



## Electric_Light (Apr 6, 2010)

bigdan1 said:


> Has any one used a this product or any thing similar?
> 
> http://www.lumencache.com


yeah, a car
the battery lets you use stuff without the alternator spinning
In place of an alternator, this uses a power supply. 
house wiring replaced by Ethernet cables carrying 12/24v 
Light Emitting Decorations.


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## bigdan1 (Jun 16, 2013)

Electric_Light said:


> yeah, a car
> the battery lets you use stuff without the alternator spinning
> In place of an alternator, this uses a power supply.
> house wiring replaced by Ethernet cables carrying 12/24v
> Light Emitting Decorations.


Sure, I was more interest in the quality of these products and the occupancy sensor features.


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## Electric_Light (Apr 6, 2010)

bigdan1 said:


> Sure, I was more interest in the quality of these products and the occupancy sensor features.


You just dropped a name and a link without saying what it is. To save everyone the trouble from having to click an external link I'll explain it. You're talking about PoE power over ethernet LAN cable attached lighting. 










It was meant for IT equipment like WiFi access points so they don't need an outlet and a wall wart at each unit. The battery at hub is kept maintained by power supply and devices are fed from the power supply, but battery picks up when power is lost. 

The power and control signals are delivered over an eight conductor 24AWG cable. That's probably about the same amount of copper as 18/2... and at 12v or 24v, you need about 10x the current to deliver the same power compared to 120v or 277v. I^2*R loss in wiring is normally considered small enough to be negligible, but with 12v/24v delivery over the same wire size over the same distance is 100 times, so it's not insignificant anymore. (for example 0.05w vs 5w loss in wiring) 

Light Emitting Decorations need a ballast resistor for each series string of diodes to get consistent current in each diode. LEDs don't act like resistors and when you wire them up in parallel, they don't share current evenly. Many high efficiency designs use triple digit voltage delivered to LEDs to minimize the loss in control circuits. So the diodes have to be arranged and resistored for 24v use or you need a step up converter and the standby power use and transmission loss are quite high. Lumens/watt from input to light would be bad. The lumen-hr per kWh efficiency is even worse due to relatively high standby loss in power supply and smart PDU.


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