12 volt lights in my old farm house, does it use less electricity than ??
Himins
Solar Expert Posts: 54 ✭✭✭✭
I have fastened half dozen 12v lights from an old motor home in various places in my house. These would be no different than the light bulbs one would see in the dome light position in older cars, or tail lights. They burn bright, and hot. I also have a decent quality 600w inverter that wants about .8 amps when at idle according to my specs, or how I interpet these specs. (GoPower TSW 600w)
Will these 12v lights use less battery than an inverter plus low wattage florescent varity lights? They are handy and I've placed them in strategic places so that i can leave the inverter off most of the time when the sun won't glow. I have used short runs and 12 awg stranded copper for them.
Will these 12v lights use less battery than an inverter plus low wattage florescent varity lights? They are handy and I've placed them in strategic places so that i can leave the inverter off most of the time when the sun won't glow. I have used short runs and 12 awg stranded copper for them.
Comments
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Re: 12 volt lights in my old farm house, does it use less electricity than ??
In short, a watt, is a watt, is a watt, regardless of voltage.
The real issue is lumens per watt. My guess is that a 15 watt 12 volt auto light bulb probably produces FEWER lumens per watt. Move to LEDs is you really want to save energy. Any bulb that "burns hot" is wastin energy heating the space rather than producing light. MY 4 watt LEDs (40-50 watt incandescent Eq) is barely warm to touch. I dare you to touch a 60 watt bulb for very long!
As for the inverter, you are going to have (possibly considerable) loses using the inverter. The point of the .8 amps is the current draw when it is not powering any load. (I assume that that is .8 amps at 12vdc,, or 9.6 watts, if it is at 120 vac it would be 96 watts,, probably unlikely for a 600 watt inverter.
Tony
V*A=W
12 vdc * 2 Amps= 24 watts
120 vac* .2 Amps= 24 watts -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
Hey Tony, that helps me with another puzzle, thanks. I couldn't figgure out how my darn cold battery could run a window fan all night long with the inverter working. I use a window fan to circulate wood heat into the crawl space under the home. This was impractical with the msw inverter, and the reason I shopped for a much smaller tsw. However .8 amps * 12v=9.6watts is still a pretty hard pull, i just don't know how to measure these 12 volt lights. I do not have funds to invest into the "nicer" stuff. I get paid very very little about 2 times a year. There, that secret is out.
Himins< organic dirt farmer with a broken foot and a baaaad hip. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
As a complete aside, why are you trying to heqt the crawl space in a cold climate? My guess is that you are ending most of your heat directlyo out doors! Consider sealing the crawl, and insulating under the floor. Clearly the reason to heqt the crawl (I'm guessing) is to keep the plumbing thawed. There are a whle myriad of soultions to under the house plumbing freeze protections that might make way more sense than trying to heat the outdoors with your wood,, even if it is free! ideas ranging from automatic drain back systems, to super insulting pipes, to low current draw, in the pipe heat tapes.
The biggest singel way to keep the water from freezing under the house,, is to have little if any water supply. Under the house. Replumbing the supplies indoors using PEX tubing is a snap, especially if you can live with exposed pipes in certain parts of the house. I tried to design all the houses that I built in cold climes by keeping all the plumbing inside. In retro, carrying the water around, through bulk heads and decorative beams to hide water supplies. With the exception of the the supply from the lake, my current house has no under the house water,, and even that auto drains back.
Tony
PS. There are whoe selecti of 12 vc LED bulbs. The way ycan tell the current draw of the 12 vdc system is either by a battery monitor, or shunted ammeter, or a clamp on ammeter. Turn each out on measure the draw. (most car bulbs will have a wattage listed on the bulb, just like a regular bulb)
http://www.superbrightleds.com/ -
Re: 12 volt lights in my old farm house, does it use less electricity than ??As a complete aside, why are you trying to heat the crawl space in a cold climate? My guess is that you are sending most of your heat directly out doors!
My first thought too - - -
Also assuming it must be for plumbing freeze protection. And yes, most of that heat is a total waste. What doesn't get out from under the house, vanishes into the earth, and even if the wood is free, there's a huge amount of work involved with wood heat. There's got to be better ways than heating the crawl space. In fact, older homes had no heat at all in their old cellars, and vegies, potatoes etc from the gardens were kept there all winter without freezing. They just had to make sure the cold wind and drafts couldn't get in, and warmth coming up out of the earth itself, would keep things from freezing. In fact, in some places many years ago, "root cellars" were sometimes built out away from the house, and they most certainly had no heat supply other than the ground itself below the frost level. They were built away from the houses, so in the terrible event of a house fire, the families winter food supply would not also be destroyed.
Re your lighting, if you cannot find cheap 12 volt LED lights, and since you already have an inverter, consider 120 volt CFL lights (they're now quite cheap) and only power up the inverter when you need light. CFL are nearly as efficient as LED, but can take a minute or two to warm up to full brightness when first turned on.
Using incandescent light bulbs is a huge waste of electricity regardless of what voltage they are, unless of course you're using the bulb to heat something. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??waynefromnscanada wrote: »CFL are nearly as efficient as LED, but can take a minute or two to warm up to full brightness when first turned on.
Actually, most CFLs are as efficient as or more efficient than most LEDs when you take the driver circuitry of both into account.
The noticeable winner is the T5 fluorescent tube, but that requires new fixtures.
I advice a mix of LED and CFL, using at least one LED on a circuit which serves security or safety, like an outside light, stairway, or night access light. They are also very good for task lighting.
Then use CFL for general area lighting where their more uniform brightness is preferred.
Also, FWIW, most LED units will work just fine at low temps like outside, while most CFLs with their low mercury content will not even start at low temps. Even worse in that respect than older tube fixtures.SMA SB 3000, old BP panels. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??Actually, most CFLs are as efficient as or more efficient than most LEDs when you take the driver circuitry of both into account.
The noticeable winner is the T5 fluorescent tube, but that requires new fixtures.
I advice a mix of LED and CFL, using at least one LED on a circuit which serves security or safety, like an outside light, stairway, or night access light. They are also very good for task lighting.
Then use CFL for general area lighting where their more uniform brightness is preferred.
Also, FWIW, most LED units will work just fine at low temps like outside, while most CFLs with their low mercury content will not even start at low temps. Even worse in that respect than older tube fixtures.
On a per lumen basis, that has not been my experience. According to my Kill-a-watt, my 13 watt CFLs put out the same light as my 4 watt LEDs.
Tony -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
To weigh this out properly you have to consider the lumens as Tony has said and also the draw of the inverter needed to power the 120 VAC lights.
If the inverter is on anyway, the DC lighting may not have an advantage. If you have to fire up 20 Watts of inverter to run one 13 Watt CFL .... -
Re: 12 volt lights in my old farm house, does it use less electricity than ??On a per lumen basis, that has not been my experience. According to my Kill-a-watt, my 13 watt CFLs put out the same light as my 4 watt LEDs.
Tony
I suspect that a large part of that difference is that the CFL is throwing its light in all directions while the LED is concentrating it more.
The same luminous intensity (lux) in the hot spot can correspond to wildly different total light output (lumens) depending on the pattern. If you only need one hemisphere or less of light output, then LEDs are going to deliver that with a lower lumen spec than a full-angle CFL. The CFLs which incorporate reflectors or are mounted in a highly reflective downlight can designed for that use should show a different comparison.
So, how are you measuring the light output?
As I said, for task lighting (reading, working, cooking, etc.) the LEDs can deliver more useful light than their lumen rating would indicate. If you look directly at the lumens per watt spec for CFL and LED, you should see a similar number. (Of course not all manufacturers give comparable lumen numbers or wattage consumption unless they are bound by government regulation to use a common standard.)
A similar problem affects lumen output ratings on fluorescent tubes depending on the design of the lampholder or luminaire they are mounted in. One advantage, for example, of the T8 tubes over T12 tubes in the same sized fixture is that they block less of the light bouncing back from the metal above them.SMA SB 3000, old BP panels. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??On a per lumen basis, that has not been my experience. According to my Kill-a-watt, my 13 watt CFLs put out the same light as my 4 watt LEDs.
Tony
That has also been my experience with the latest LED lights. There have been some pretty big advances lately.
And re the CFL's not starting in the cold, that used to be the case with the early designs, but until I switched to LED for all my 7 outside lights, 2 on the deck and the rest spaced in the trees down the driveway, I never had a problem with the CFL's (I used) starting in our coldest winter temperatures, minus 25 C, but on those coldest nights, they hung around half brightness, never getting beyond that until the weather warmed up. The LEDs I'm now using love the cold, instant on, instant full brightness. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??waynefromnscanada wrote: »but on those coldest nights, they hung around half brightness, never getting beyond that until the weather warmed up.
I wonder what the luminous efficiency of them was while in that "half-brightness" mode? Since the mercury vapor pressure was well below the design level, I suspect the efficiency was down too.SMA SB 3000, old BP panels. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??I wonder what the luminous efficiency of them was while in that "half-brightness" mode? Since the mercury vapor pressure was well below the design level, I suspect the efficiency was down too.
Oh yes, the efficiency of the CFLs must be in the bottom of the ditch when used outdoors on bitterly cold nights. No question about that. They're next to useless when that cold, even though they will start. Must be some other gasses in there to initiate the arc, but without the mercury vaporized, they're very, very dim. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??On a per lumen basis, that has not been my experience. According to my Kill-a-watt, my 13 watt CFLs put out the same light as my 4 watt LEDs.
Tony
Hold the phone. Are you saying you have found a 4 watt omnidirectional LED bulb that is advertised to have the same luminosity as a 13W CFL? Every one I have ever seen comes in at 1/3 the lumens. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??Volvo Farmer wrote: »Hold the phone. Are you saying you have found a 4 watt omnidirectional LED bulb that is advertised to have the same luminosity as a 13W CFL? Every one I have ever seen comes in at 1/3 the lumens.
Icarus, a Kil-A-Wat meter is not for measuring lumens, so your statement is a tad confusing. Could you re-phrase your observation? -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
I have a number of LED conventional shaped bulbs, Edison base, that draw 4 watts according to the KAW, and put out as much light (to my eye) as the 13 watt CFLs that they replaced. I have no meter to actually measure the lumens. The light color is pretty good, a bit cool for my tastes however. They were ~$15 for a 3 pack at Costco.
I also have some 4 watt high intensity LED reading lights (both floor style and table style, on goose necks) fro IKEA that also draw 4 watts and make a fantastic reading light, or bench light.
Remember, your milage may vary.
Tony -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
Phillips here in the North is putting a comparison display in a lot of the retailers to flog their Edison base 'BULB" type LEDs... Now if the price per would come down from $35 or so
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Re: 12 volt lights in my old farm house, does it use less electricity than ??
Can't argue with any of that.I have a number of LED conventional shaped bulbs, Edison base, that draw 4 watts according to the KAW, and put out as much light (to my eye) as the 13 watt CFLs that they replaced. I have no meter to actually measure the lumens. The light color is pretty good, a bit cool for my tastes however. They were ~$15 for a 3 pack at Costco.
I also have some 4 watt high intensity LED reading lights (both floor style and table style, on goose necks) fro IKEA that also draw 4 watts and make a fantastic reading light, or bench light.
Remember, your milage may vary.
Tony
It really points out that the proper metric for using either CFL or LED is the amount of useful light it produces where you need it, not its output in lumens. And for many uses, the LED has a big advantage there. But if you are trying to get omnidirectional light (a typical old-fashioned table or floor lamp with a shade, for example) the CFL will be just as efficient as an LED. The problem in that case is really that the fixture is inherently inefficient (i.e. it has a "shade") and you should look at replacing it. Other than unenclosed open sockets in closets or on ceilings, much of the light from a CFL that is designed as a replacement for a type A bulb will be wasted. There is also a big problem with any fluorescent that they have to emit light in all directions from the tube itself, and any pattern has to be supplied externally via a reflector. An LED is inherently directional, and much of the effort in making LED units for replacement of type A bulbs goes into making them less directional.SMA SB 3000, old BP panels. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
The last time I bought bargain price LEDs from Costco (over two years ago) they were recalled because they lost output too rapidly (30 days of 24 hours per day and they were almost dim.)They were ~$15 for a 3 pack at Costco.
Remember, your milage may vary.
Tony
I hope these are better, but if they are not at least Costco will stand behind them.SMA SB 3000, old BP panels. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??westbranch wrote: »Phillips here in the North is putting a comparison display in a lot of the retailers to flog their Edison base 'BULB" type LEDs... Now if the price per would come down from $35 or so
Yup. The cost of an LED bulb around here can buy you a lot of kW hours from BC Hydro. Not competitive by any means. I calculated a pay back time of 20+ years for changing out the kitchen lights. :roll: I ain't gonna live that long. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
I have some of the "current batch" of LED bulbs from Costco (smattering of types)--So far, they all seem to hold up OK. Pretty much all of them are "heavy" because they have a fair amount of aluminum heat sinking to keep the LED cool(er).
The ones that failed (as I recall) were some flood lamps with a whole bunch of T1 3/4 type LEDs (the type in a clear plastic--sort of 22 caliber bullet shape with the leads out the back)... Those have very poor ability to remove heat from the LED die/phosphors (used to make white light)--And end up during brown/black/losing a lot of output in a few hundreds of hours of use.
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
Of course, you could always build your own LED fixture.
I have an 18W DIY fixture that I have running over a 3 gallon "pico" salt water aquarium. Cost was less than $15 and it produces an incredible amount of light - the corals in that tiny tank are thriving. FWIW, this fixture has been running for 12hrs a day, 7 days a week, for over 2 years and is just as bright as the day that I first turned it on. The LEDs that I used have a 140 degree spread. Since this picture was taken, I've added lenses to focus more of the light into the tank.
Attachment not found. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??
But do you plan to live long enough to be unable to climb up and replace the bulbs? :-)Cariboocoot wrote: »Yup. I calculated a pay back time of 20+ years for changing out the kitchen lights. :roll: I ain't gonna live that long.SMA SB 3000, old BP panels. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??I have a number of LED conventional shaped bulbs, Edison base, that draw 4 watts according to the KAW, and put out as much light (to my eye) as the 13 watt CFLs that they replaced. I have no meter to actually measure the lumens. The light color is pretty good, a bit cool for my tastes however. They were ~$15 for a 3 pack at Costco.
I also have some 4 watt high intensity LED reading lights (both floor style and table style, on goose necks) fro IKEA that also draw 4 watts and make a fantastic reading light, or bench light.
Remember, your milage may vary.
Tony
I do appreciate your quantification of lumens being subject to your eye. I have both CFL and LED omnidirectional bulbs scattered around here and watt for watt, the brightness seems about the same to my eye.
We have some CFL 15 watt bulbs in PAR30 configuration in ceiling cans. I replaced one of them with a LED PAR30 , and the light is much harsher and less warm with more distinct shadows. Directional light has its time and place, but I want general house lighting to be warm and omnidirectional. Harsh light hurts my brain. -
Re: 12 volt lights in my old farm house, does it use less electricity than ??But do you plan to live long enough to be unable to climb up and replace the bulbs? :-)
No climbing needed; I can reach them all from ground level.
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