12 volt light fixture?

coachlawcoachlaw Registered Users Posts: 10
Hello, I'm brand new here. I had a look around and I've got to say that I've never been so confused about 12 volt stuff.

I grew up using a 12 volt solar cell to trickle charge 3 deep cycle batteries. My dad is a chemical engineer and he put the system together. It was enough to light our 3 room fishing camp for a few nights in a row and watch a little tv before you had to give the batteries a rest. It was really great not to have to fire up a noisy generator. We would sit on the porch and just enjoy the evenings. Ahhh, but all that ended with a hurricane in 1997. The whole camp went. :(

Just recently I got my own fishing camp here in Texas. I still hate the noise of a generator. I go out there to enjoy the peace and quiet, you know what I'm talking about? Well anyway I've been trying to replicate the setup we had at the old camp. I got 3 batteries, a nice big solar panel with a charge controller. I use old lamps that I've gotten for free. I pop the plug off, add battery clips and use 12 volt incandescent 50 watt bulbs from the auto parts store. Everything works just fine, but I know it can be a lot better. I also like using a fan for the hot months upcoming. I've got a little 150 watt inverter to run a 20 inch box fan and everything works great. I even run the little black and white tv off of the system.

Problem is, in the summer months with using a fan, I really need some more efficient lights to keep from cycling the batteries too deep. I'd like to go fluorescent and I did try the spiral fluorescent screw in 12 volt bulbs to replace the incandescents, but they only lasted about 3 months. I was pretty upset about that given their price, but they really were a lot more efficient. Talk about junk though. I only got about 12 nights out of them.

I'm looking for advice about what to get. I wouldn't mind getting a few of the fluorescent 12 volt fixtures, but I'm very confused about which way to go. Should I try the screw in bulbs again? If so, where can I get some quality ones? Should I go with fixtures that use regular fluorescent bulbs but run off of 12 volt? I know I could just get regular ones and run them off an inverter, but that kind of leads to less efficiency, plus I'd rather not have to buy another inverter.

If anyone has any advice, I'd sure appreciate it. But before you type, please know this. I am a history teacher and a coach, not an engineer like my dad. I finally just found out that PVC is a fancy way to say solar cell. Please don't use any acronyms or abbreviations that a regular guy like me won't understand. And finally, also being a teacher, I have to be very price conscious. Nothing too fancy. It's a fishing camp, not a home. Many thanks in advance, Sandy


  • BB.BB. Super Moderators, Administrators Posts: 33,313 admin
    Re: 12 volt light fixture?

    Sorry--we do fancy-over thought--over designed--and over priced. ;)

    Not a problem... The first thing is to address your loads.

    LED's and CFL's are much more efficient than filament bulbs. Typically, LED's are great for reading lamps or focused applications. CFL's are good for lighting a room.

    Many times, it is better to get a nice (small) AC Inverter to run your loads vs finding native DC devices--because, when run on solar RE systems, the battery bank voltage ranges from 10.5 to 15.5 volts--frequently too large a range for 12 volt CFL's, laptop car adapters and such (a car lighter outlet is typically 12-14.2 volts or so).

    And, the AC devices are many times less costly, last longer, and you can string the wires farther (120 VAC at 1 amp is much easier to send around vs 12 VDC at 10 amps -- P=I*V=120v*1a=12v*10a=120watts).

    So--first thing, ideally is to find energy efficient devices that you can use at your cabin (the old "boom boxes" with an AC plug, 120 VAC 13 watt CFL's, etc.). A Kill-A-Watt meter is ideal for you to measure your loads. And very reasonable at $30 or less.

    wind-sun_2050_2425819Kill-A-Watt AC Power Monitor Meter
    P4400 Cumulative Killowatt-Hour Monitor

    Electrical 101--Watts is a rate (like Miles per Hour). And Watt*Hours is equvalent to distance driven (Miles).

    So, a 10 watt bulb running for 8 hours:

    10 watts * 8 hours = 80 Watt*Hours

    or a 100 watt bulb running for 1 hour:

    100 watts * 1 hour = 100 Watt*Hours

    You need to know your peak watts (such as 10 watts + 100 watts = 110 watts peak). And your total power used in a day (80WH + 100 WH = 180 Watt*Hours).

    Once you know the basic energy needs, you can then size the inverter, batteries, solar panels, and charge controller.

    You can decide to use 12 VDC components and save the cost of the inverter--but, I would suggest the Morning Star 120 VAC 300 watt inverter to power your cabin... I think you will be very happy with it.

    wind-sun_2052_15352986Morningstar SureSine, 300 Watt Sine Wave Inverter 115VAC

    It is about $250--but it is a True Sine Wave inverter--much better to run small electronics and such with vs the $25 MSW (Modified Square/Sine Wave) Inverter.

    I have to go right now--But it would be real helpful if you can decide on your loads (watts, watt*hours per day) and if you want AC or DC power (the AC/DC decision can be put off for later--it is not a huge issue).

    Once we know the size of the loads--the rest of the decisions will be pretty straight forward (if not cheap).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: 12 volt light fixture?

    With a simple inverter you can power 120vac CFLs,, ranging in wattage from 3-~20 watts.

    Our system started similarly, and has grown into a full fledged system. Remember that loads will grow,, as I think you are learning.

    We live with ~2-300 watts of panel, 300 watts of inverter, and 450 ah of battery,, it is a pretty well balanced.

    Good luck,

  • BB.BB. Super Moderators, Administrators Posts: 33,313 admin
    Re: 12 volt light fixture?

    I think that Tony/Icarus also has a 12 volt ceiling fan that is very happy with (good air movement, low power).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: 12 volt light fixture?

    In fact,, what I have is a hybrid system,, so to speak. Parallel 12vdc/120vac systems. In any room in the house I can turn on 12 vdc lighting so that I have emergency light regardless of the inverter. I can also use 120vac for lighting (and do for almost all lighting) if the inverter is on. The 12vdc powers the fridge control board, the radio (A car type radio) the water pump, telephone, paddle fan, as well as the inverter.

    120 powers the general lighting, satellite modem, small charging,, (drills, lap tops etc).

    It has evolved over the years from a generator powered all 120vac system,, to an all 12vdc system,, into the hybrid. Before good cfl bulbs came along, it was touch to get low wattage 12vdc lights,, so we used car bulbs almost exclusively. 120 vac cfls are cheap, provide good light, and use small amounts of power. When leds make the leap in output, color and price,, we will have power to burn! (getting closer all the time!)

  • coachlawcoachlaw Registered Users Posts: 10
    Re: 12 volt light fixture?

    Sure is lots here to digest. I assume that CFL means a fluorescent bulb?

    Since I just shelled out big bucks for batteries, panel, and charge controller, I don't see myself buying anything like a pure sine inverter at the moment. My little modified sine inverter is good, and I got it on sale for $20.

    I understand about running AC wiring being much more efficient over distance. Will there be any problems running AC fluorescent fixtures from a modified sine wave inverter? It works great with the little black and white tv, so I assume it would be safe with an AC Fluorescent light fixture.

    I'd like to hear more about the 12 volt ceiling fan too!

    Being single thus far, I think I'm going to start looking for an electrical engineer to marry :)
  • BB.BB. Super Moderators, Administrators Posts: 33,313 admin
    Re: 12 volt light fixture?

    CFL is compact florescent lamp--those "twisty bulbs".

    You can read about the MSW vs TSW inverter question in these couple FAQ's from our host's (NAWS) website.

    All About Inverters
    Choosing an inverter for water pumping

    Many people have good luck with CFL's and MSW inverters... And some have reported "buzzing", and a few others yet--report lamp failures and other strange problems.

    Both the MSW inverter and 120 VAC CFL's are cheap--see what happens.

    I would suggest that you look at getting a battery monitor... It will probably save you from damaging your batteries (undercharging, over discharging + lack of water probably kill the most batteries)--especially if you do not use a hydrometer much to check the specific gravity. The Trimetric meter seems to be a good, lower cost, unit (from other posters here).

    I assume the 12 vdc fan is similar to these...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: 12 volt light fixture?

    I've never had a problem running CFLs on MSW inverters. Used one for years,,, a bit of buzz on AM radio but other than that no problem.

    Fan like this one,,, I painted all the brass black though, http://www.backwoodssolar.com/catalog/fans.htm#LARGE%20DC%20FANS

  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: 12 volt light fixture?

    I've been looking, and these look pretty interesting...


    Edit: Forgot to mention that I think the plcc-2 is a .5 watt, so these 10 dollar lights should use consume 6 watts.
  • coachlawcoachlaw Registered Users Posts: 10
    Re: 12 volt light fixture?

    Guys, I really appreciate y'all's help on this stuff. Some great links there! I didn't get a chance to mess with anything this weekend. We're still rebuilding from Hurricane Ike, so there are a lot of projects going on. On the upside I caught a good mess of speckled trout. 8)

    I'll be doing some experimenting next time I go in a couple weeks. Keep those links coming if you know of anything cool you think I could use. - Sandy
  • hunter44102hunter44102 Registered Users Posts: 24
    Re: 12 volt light fixture?

    Another option if you don't want to do conversions and inverters -

    use solar camping lanterns that have Fluorescent 'U-Tube's - heres one with 9 watts and has its own Lead-Acid battery that runs up to 12 hours. You can also hook it up to your system and charge it up:


    LED version:

    These lanterns are pretty bright, and they are portable/waterproof also
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