stand alone lighting / lamps

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Mike at Energy Commission
Mike at Energy Commission Solar Expert Posts: 50 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
My next project will be to build a stand alone lamp using an LED bulb, plan is to convert thrift store lamp, use a small sealed 12v AGM battery. 12volt DC bulb would be nice but can't find an LED bright enough, so if I have to, I will go with a 120v AC bulb and a small car inverter. My question is....how well does a 120v AC LED bulb work with modified sine wave?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #2
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    Re: stand alone lighting / lamps

    MSW is always a gamble... Some ballasts are designed so that MSW does not hurt them at all... Others can overheat and die an early death.

    If you have a Kill-a-Watt meter, my test would be to run the AC lighting system on pure sine (or utility power) and read the VA / PF (volt*amps and Power Factor). And then do the same reading on MSW. If the TSW and MSW VA/PF numbers are very close, then I would not worry.

    However, if the VA on MSW is 20% higher than TSW, and/or the PF numbers are way different (guessing 0.8 or higher on TSW and 0.6 or low on MSW), then I would worry the ballast would over heat.

    However--You should be able to find some 12 Volt track light LED bulbs--They are pretty bright and I think a few people have used them with good success.

    http://www.ledlight.com/12-volt-led-track-lighting.aspx (Don't know anything about website or bulbs)

    With any of these experiments, don't spend a lot of money until you have done initial testings.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
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    Re: stand alone lighting / lamps

    I have one 12 volt LED track light "bulb", and was surprised to find it extremely voltage sensitive. Hopefully you'll find one that isn't. Running on 12 volts, it's light output is really useless, so dim it's only good for finding the bulb in the dark. at 13.5 though, it makes a subdued night light, but if run on 14.5 it's bright enough to read with. (And I can hear my long departed from this world grade 8 English teacher telling me: ""Never use a preposition to end a sentence with.")
    If however you too find the "track light" LED not suitable, you might well have better results with a 12 volt automotive interior lighting LED "package", such as can be found in the auto section at Wal*Mart.
    If you can find a useable 12 volt light, you'll eliminate the power losses of running an inverter, many of which will suck back more power just to stay powered up, than the LED light itself would consume, thus doubling or more the power needed to light the bulb.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #4
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    Re: stand alone lighting / lamps

    Perhaps something like this might be better
    http://www.tmart.com/1156-5050-24-Led-Turning-Car-Light-Bulbs-White_p143191.html
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #5
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    Re: stand alone lighting / lamps

    MaEC,

    So, guess that the Thrift Store lamp is looking for an Edison base?

    Here is a 12-ish V Lamp assembly that has reasonable output:

    http://www.superbrightleds.com/moreinfo/trailer-lights/10-oval-dome-light-led-fixture-with-switch-for-night-light-mode--cree/1492/3422/

    It is not inexpensive. And it is now well known just how you plan to use lamp. The SuperBrightled.com site has a reasonable search-narrowing function that might help find something in a 12 V emitter that would save a reasonable amount of power vs using a 120 VAC bulb and an inexpensive inverter, depending on how many hours per day that this lamp needs to operate.

    Vic in the Center of Nowhere
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #6
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    Re: stand alone lighting / lamps

    I have a bunch of 4 and 5 Watt 12V MR16 bulbs. I find that they're great for reading or task lighting. For general room lighting I use 12V 13W CFLs.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #7
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    Re: stand alone lighting / lamps
    waynefromnscanada wrote: »
    If you can find a useable 12 volt light, you'll eliminate the power losses of running an inverter, many of which will suck back more power just to stay powered up, than the LED light itself would consume, thus doubling or more the power needed to light the bulb.
    But if you plan to have a lot of 12 volt lights and other 12 volt loads, you will find that you have to run more expensive large wire to reduce voltage drop. At least if you are wiring a good sized cabin or other building.
    SMA SB 3000, old BP panels.
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  • RandomJoe
    RandomJoe Solar Expert Posts: 472 ✭✭✭
    #8
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    Re: stand alone lighting / lamps

    For a portable lamp, being able to go straight 12V is nice - less hardware required, lighter weight, so on - but in my experience so far it can be a compromise in other areas. Most of the 12V bulbs (CFL and LED) I've come across have horrible color rendition, generally being extremely monochromatic. The few that are acceptable can be quite expensive! I have a small collection of portable / handheld 12V powered LED and CFL lamps, but only use them for work lights or very temporary lighting.

    If I want a more general room / area light I'm much happier with a standard 120V CFL or LED bulb running on inverter. They have a much better color spectrum, and are a lot cheaper thanks to mass-market volume (especially CFLs). Another big benefit - they're readily available if I need a replacement. I can buy 120V bulbs just about anywhere, 12V ones are harder to come by in a pinch.

    I don't run anything on mod-sine anymore though. Still have an old Radio Shack 220W mod-sine inverter, and did run a CFL bulb with it for a while during the outage that got me interested in solar / backup power. It ran fine, but I didn't run it long enough to know what effect if any it would have on life expectancy. Later I was running my work laptop with it on a job site and the PSU got hotter than blazes and started smelling like it was melting! I now only use true-sine inverters, the cost (to me) is low enough not to be an issue. (Same PSU continued to work fine, cool and no smell, after that so it wasn't just a dying PSU. The inverter checked out okay too.)

    Back to a cheap 12V version, if you aren't looking specifically for a screw-in commercial bulb, you could fabricate something relatively easily. I found some LED strips at the automotive store intended for accent lighting. They have various colors, including white. I was surprised to find some of the white ones were a warmer hue than the icy-blue I usually see. (Perhaps "cool white", still a long way from my preferred "warm white".) They have 3M sticky-tape on the back, and spiraling that strip in a tight coil around a piece of PVC would make a decent "general illumination bulb" quickly and easily. Wire to 12V and done.
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