Infrared light switches

[Marco Polo]

In the process of designing an of the grid home in New Mexico.  Currently stuck in LA and living on the grid.

I am interested in the infrared light switches to turn lights on and off when you enter and leave a room.  I occasionally leave a light on all day and don't discover it until I come home 12 hours later.  I can't afford to do that living of the grid.

These switches must consume power.  Does any one know how much?  Are they a net saver of looser of energy? Or will that strictly depend on habits and usage?  I will design curcuits with swithches in them to turn off all appliances other than the frig.

Thanks,

Mark

Resectioned

[commanda]

The only PIR (passive infra-red) switches I've seen commercially all run off mains. In an off-grid home this means leaving an inverter on 24/7 so the PIR's have power to sense when someone walks in the room and wants the light on.

The idle current for any inverter to run 24/7 is going to far outweigh any potential savings from the PIR's.

Gizmo over at the backshed

http://thebackshed.com/Windmill/articles/12vSensorLight.asp

did an article on hacking a mains powered PIR to run at battery voltage. Obviously, this would necessitate using lamps at the battery voltage to remove the need for an inverter.

Amanda

[Volvo farmer]

Maybe it's easier to redesign your habits than your house. I've trained my kids aged seven and four to turn off the lights when they are done using them. I almost never catch them leaving a light on. If a four year old can do it, an adult can probably learn too.

Wall switches are handy for shutting stuff off. We put a switched outlet in every room and use about half of them. The one that is especially handy is the one for the entertainment center. Flip a switch when done with the television and all those phantom loads go away.

We've found these things to be handy.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95276

They're bright enough to take a whiz by and also bright enough to keep from falling down the stairs. Battery life seems to be pretty good as we've had some for three months now on the original batteries. They will run on NiMH cells too.

[TAH]

I have tried to use one of these without good success. The problem seems to be that one CFL doesn't draw enough current to make the on/off circuit function. It would not turn off completely and sit and flicker. My inverters are always running anyway so that wasn't as big of a concern for me. I never did check to see how much power it used since I didn't want to add two or three bulbs just to make the switch trigger.

[kitestrings]

Marc,

We've used a couple of 12VDC heat/motion sensors made by RAB.  I believe the procduct name is "Stealth".  There very high quility as these things go.  We have used one on the garage for a number of years to activate lights and energize the OH door operators when someone pulls in the yard.  Backwoods Solar is one source that carries them (I have no affiliation, and I'm sure there are others) - just one supplier that we've used.  We've also used simple, mechanical spring-wound timers, and switchable light/appliance strips in some cases.

I agree with Volvo farmer that it's best to instill the right habits.  Personnally, I hate having the inverter run for small loads that can be handled other ways.  Phantom loads can be significant now a days, and off-grid a kWh or (amp-hr) saved is an kWh earned.  Good luck.

-kitestrings

[Marco Polo]

Thanks for the input.  It is good to know that the commercially available ones are not compatible with CFls and probably would not work with LEDd either.  It is probably best to put manual switches in as many circuits as possible and just turn the circuit off when not in use.  The market for 12V lighting probably is not great enough for the manufactures to make switches specifically for that application yet if ever.

[catweazle]

Stumbled across this. Haven't used or bought them (I'm not interested in them) but thought of your question. FWIW:

http://www.a1parts.com/kits/Kits69.html

Check out Kit 30 (PIR movement detector)