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Thread: 12v Lighting

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    Default 12v Lighting

    I had some trouble with the search option so this is probably already covered somewhere but here goes...We are currently all wired but it looks like our cabin will not be hooked up to the grid for a while. Right now we are running a Honda 2000 and usually just jacking it into a 3 outlet circuit for power. This works perfectly fine because we only need some batteries, phones charged, and the occasional small appliance. Now that the sun is staying down longer we are in need of a better lighting system. Preferably one without using the generator. I was thinking I could rig a 12v to a couple LED strips or something similar which I can charge during the day when we run the generator and use at night when we would prefer quiet. Essentially I am wondering if somebody is running a similar SIMPLE system like this. Or any advice? Thanks for the help.

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    A friend of mine wired a shed with a couple light bulb receptacles 12volt bulbs an on/off switch to a simple marine battery, seemed pretty simple to me & it worked, I'll pick his brain tonight to see if he did anything special or just simply wired up the same as you would a standard wiring.

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    Member dkwarthog's Avatar
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    We run a system just like you described. One deep cycle 12v battery with a cheap 400 watt inverter and a under hood type automotive trickle charger. We also added a small solar panel from costco to top off the batts on the unlikely chance that we see some sunshine. We have one outlet in the house that is fed from the inverter and 5 strings of led Xmas lights hung up around the house. They are less than 5 watts per string so the load is tiny. We split the light string into two halves of the house with a r
    Cheap remote outlet. That way we can turn on the second half of the house lighting with the push of a button. Hope I described it well enough. I was amazed it took me so long to come up with this system. We use a 2000watt Honda and run it about 3-4 hrs in the evenings to run bigger loads.

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    I have a more refined system than what you want but the principle is the same. Battery, charger, generator, solar panel, inverter. Frigid North has some great 12"/12 volt LED lights that shine bright with small power use. Just remember to use stranded wire for the 12 volt runs....NOT solid copper. On-line sources have most of what you need to build any LED/12 volt light you can imagine.

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    Otter, could you go into a little more detail about not using solid copper wire???????

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    I do not understand why you can not use solid copper wire on a DC circuit. Solid copper wire is use in circuit all the time.

    Could the reason be?
    In this application a person would normally use the existing house wiring solid 10/3 or 12/3. The only problem that I can see, is if you solder a #10 or #12 solid wire to a LED light strip it is very stiff and it could break the light strip. If you use stranded wire it would flex and you would not have a problem. Using a short pig-tail of #18ga stranded wire between the LED light strip and the solid wire would be a simple solution.

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    I have been told by solar supply companies (note plural) and a journey-man electrician there is too much heat build-up in solid wire with DC current. And used stranded in my system-though the solar company provided solid wire from the panels to the controler
    Doing some research, there is a 'skin effect' when using solid wire that will become an issue if you get above 60Hz. The solid wire carries current on the outside of the wire (skin effect) as opposed to the stranded carrying current evenly across the entire wire.
    In the real world it is a 50/50 call.
    Stranded wire:
    larger diameter
    more flexible
    better contact so lower resistance
    better in an application where there is movement and vibration
    better crimping for lug hook-ups
    carries more amps
    hope this helps

    Quote Originally Posted by Big Bend View Post
    Otter, could you go into a little more detail about not using solid copper wire???????

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    Because stranded wire is more flexible their for it's a better choice when making long runs not because it carry more current.

    Thing to consister.
    The frequency of DC (direct current) is zero it has no frequency there for there is no skin effect to worry about. The formula for DC resistance is R= E/I there is no mention of frequency.

    There is NO difference between the DC current rating of solid or stranded wire. http://genuinedealz.com/voltage-drop.html

    You mention stranded wire is larger than solid again there is no difference in size between them look at the wire table there is no separated listing for solid or stranded wire.

    If there was a difference current rating between crimping a solid or stranded wire there would be separated lugs for the two types of wires and there is not.

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    I have a full-blown big inverter system but for late nights when we don't want to hear the inverter we use 12v. Get your 12v battery charged however you prefer. That doesn't matter. Hook it to a 12v distribution panel from AK Battery or Alternative Energy. That'll allow you to split to several different 12v appliances and will give you a 12v automotive fuse for each leg. You can do a simple disconnect right at the power source so nothing draws power while you're away (in case the kids forget to turn off their reading light). I wired all my 12v with typical lamp cord. Cheap, flexible, and easy to get at Frigid North, Lowes, etc. Speaker wire works, too. I used 12v fluorescents because LEDs weren't all the rage at that time. No regrets. They work great.

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    Member kodiakrain's Avatar
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    Thought you ight be interested in a Marine Industry link or two

    we use 12 volt extensively on small boats, and everything from small and affordable solar panels for your batteries,
    to Invertors when you need to convert over to AC is covered well if you search around these websites

    Because it's all built for offshore systems, there's an inherent reliability requirement in most of this stuff, can't afford to break down and /or lose 12volt power out on the anchor, so it's well built and corrosion proof stuff, with light load draws

    Lots of LED stuff taking over the market these days, amazing lighting for the power required

    Here's a couple to get you started
    http://www.defender.com/category.jsp?path=-1&id=65136

    http://www.defender.com/category.jsp?path=-1&id=328

    http://www.boemarine.com/subcategory...Products=page2

    Some are ridiculously expensive as it is for money making operations or for Rich Guy Yachting,...but keep looking around
    there's a lower end that is still quality, would be good for the woods place and last forever
    Ten Hours in that little raft off the AK peninsula, blowin' NW 60, in November.... "the Power of Life and Death is in the Tongue," and Yes, God is Good !

  11. #11
    Member Grayling Slayer's Avatar
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    Default Re: 12v Lighting

    After trying several led lights this is what I found to be the best and most economical solution.

    http://www.amazon.com/Super-Bright-L...ords=led+strip

    I originally bought the 3 strip set, but then ordered more after seeing how bright they were. I have several strips in the kitchen and then a row across the beam on the loft. It way brighter then any other 12v light and only uses a few watts. When you get power you can then still use them with the included transformer. I ended up installing another set as under cabinet lights in my kitchen a home. The cool white is very bright, and the warm white is more like a traditional bulb. I used cool white at my cabin and warm white at my house where it is more accent lighting. During the winter I leave them on almost all the time to save electricity.
    "I'd rather be fishing!"

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    I can't believe all of the misconceptions on stranded vs solid copper wire here. About the only truths I read were straded works better in applications requiring flexibility (true) and the ohm's law equation (e=I/R or Volts = Amps/Ohms). True there is such a thing called "skin effect" but why even mention it on a DC topic when "above 60Hz" is an AC issue AND all house current and generator provided AC is going to be at or near 60Hz. If this were true, why would ALL residential and commercial wiring be done in solid wire. DC doesn't alternate, it's DC (DIRECT current.) (PS: "skin effect" is more an issue for RF transmission lines.)

    Stranded wire does not "carry more amps" than solid wire, however, it will carry voltage further with less voltage drop due to line loss. (In other words, it's a better conductor.)

    Oh yeah, it is true that you can solder and crimp stranded wire easier than solid; I'll definitely agree with that. Stranded wire will install easier, especially at lower temperatures. Once the wire is in, as long as you don't mess with it, temperature isn't that important. Use a air of ratcheting wire crimpers (about $50 Frigid) or, at a minimum get a good pair of Klein, or channel lock wire cutter/crimper pliers (about $25 at AIH) for making all of your wire terminations (ring terminals splices, etc.). Don't use the cheap-o multi purpose pliers/crimpers/wire strippers that they sell at Frigid for $10; they're crap, they don't make good connections, and before long the little plastic crimp on pieces are pulling off the wire. By the way, the Channel Lock and Klein pliers at AIH are made in USA and the more expensive Ideal brand at Frigid are made in China.

    I've been doing wiring, wire repairs, and electronics on aircraft for about 10 years, so I think I know a little about how to do this lol.

    Lastly, I used to work at Frigid North, and I know the lights you guys are talking about. Go check out Amazon.com and get them for half the cost (that's where Tom buys his) and free shipping.

    Oh, one more thing. from my experience at Frigid, I can say that LOTS and LOTS of people have DC lighting systems in their cabins; it's very common and works well. The one thing you have to worry about is the temperature of the batteries. Deep cycle marine/RV batteries are going to get you the best amp/hour rating vs price, but they can't handle freezing temps; the electrolyte freezes and bulges the battery case. Same for those smaller sealed lead acid (SLA) batteries at Frigid North. Renewable Energy Systems , on Dimond across from Costco, sells some batteries that are designed for cold weather, but I'm sure they're $uper co$tly.

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    I agree with a lot of what you say specially the ones I agree with. LOL

    I confused why you would say stranded wire carry’s more VOLTAGE than solid wire.

    There two difference ways to look at the question. If you look at the hi-voltage rating of a wire the insulation is what determine how much voltage it will carry not if it stranded or solid.

    There is also the temperature rating of the wire at what point the insulation melts exposing the wire. Again this is to do with the type of insulation not if it stranded or solid. You could argue that a wire that has less resistance would have a less voltage drop and there for CARRY MORE VOLTAGE to the load. This is true except the size of the copper wire is what determine the voltage drop, not if it stranded or solid assuming everything else is equal.


    What is stranded wire? It is several solid wires in a single jacket, if you took a length of stranded wire with 10 strands and measure it resistance let say it 10.00000 ohms. Now remove a single strand and measure it, you will find it is 100.00000 ohm (everything being equal) and we all know that 10-100 ohms in parallel= 10 ohms. Again proving there is NO difference between stranded or solid wire.

    Would someone please show me a wiring table that said stranded wire carry more current than solid.

    I ask Google that question and was not expecting what I found not only is there a difference but solid wire carry more current than stranded or does it??????????? LOL


    http://www.electronicspoint.com/curr...and-t5998.html

    Zarbol Tsar" <(E-Mail Removed)> wrote in message
    news:95B4D128678B651D7E@130.133.1.4...
    > Would a multi-strand flexible wire have the same current carrying
    > capacity as a solid single stranded cable of the same cross section.
    >
    > For example ... a multi-strand with a cross section for its wire
    > portion of 0.75 mm squared and a single strand cable also of 0.75 mm
    > squared.

    For No. 12 AWG Table 8 of the NEC does list two different DC resistances for
    stranded and solid copper.

    DC resistance per 1000 feet for solid is 1.93 ohms

    For stranded the DC resistance is given as 1.98 ohms per 1000 feet.

    So solid should have a slightly higher ampacity.

    If we use Table 310.16 of the NEC to determine RCA and substitute into the
    Ampere calculation we can find the approximate differences in ampacity.

    From Table 310.16 using 75 degrees C as the ambient.

    I = 25 amperes, TC = 75 degrees C, and TA = 30 degrees C and RDC = 1.98 ohms
    per 1000 feet or 0.00198 ohms per foot.

    This converts to 1980 microhms.

    From I (in kiloamperes) = SQRT(( TC-TA)/RDC*RCA))

    Or

    RCA=(TC-TA)/RDC*I*I

    Or RCA = (75-30)/1980*0.025*0.025

    RCA = 36 thermal ohm feet

    For stranded, I = 0.025 kiloamperes from the table

    For solid No. 12 copper

    I (in kiloamperes) = SQRT ((75-30)/1930*36)

    or I = 0.0254 kiloamperes

    Then the solid No. 12 copper would have a 0 .4 ampere increase in ampacity.

    This is a 0.4/25 *100 or only a 1.6 per cent increase.

    Considering that ampacity tables are approximations, this increase in
    ampacity does not exceed the error of approximation.

  14. #14

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    I forgot was this question about 12v lights or a trip to the moon? A lot of technical info. for something that started out so simple.

  15. #15
    Member Grayling Slayer's Avatar
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    Default Re: 12v Lighting

    Since we are talking about 12v led lighting we are dealing with loads of 2-10 watts which is less than 1 amp at 12v. 18g 2-conductor thermostat wire works great and is rated up to 10 amps which could power a string of 60 led strips. Unless you plan on installing a commercial solar grid the last couple of posts are irrelevant to the topic. I work in telecom and everything is dc powered.
    "I'd rather be fishing!"

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    I never said it would carry more voltage. I said it would carry the voltage further with less voltage drop.

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    Quote Originally Posted by FL2AK-Old Town View Post
    The one thing you have to worry about is the temperature of the batteries. Deep cycle marine/RV batteries are going to get you the best amp/hour rating vs price, but they can't handle freezing temps; the electrolyte freezes and bulges the battery case. Same for those smaller sealed lead acid (SLA) batteries at Frigid North. Renewable Energy Systems , on Dimond across from Costco, sells some batteries that are designed for cold weather, but I'm sure they're $uper co$tly.

    Flooded lead-acid batteries (marine/RV) can certainly handle freezing temps. Just keep them charged up. Our battery bank of Costco "golf cart" batteries, which are not expensive battery-wise, has cycled through numberous sub-zero days and still work fine.

    As for the original post, we went the inverter/AC lights and appliances route. 110 AC stuff is much more plentiful and less expensive. For lights and cell phone charger, a small inverter would work fine.
    Last edited by NRick; 09-19-2012 at 16:52. Reason: spelling

  18. #18
    Member Grayling Slayer's Avatar
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    Default Re: 12v Lighting

    I have 2 deep cycle rv batteries at my cabin that have been through many winters with at -50 with no problems. I always make sure they are fully charged when I leave and disconnect the master switch.
    "I'd rather be fishing!"

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    Golf cart battery are a good choice for a cabin they will last a long time between charging. The problem with large batteries is it take a long time to recharge then. If you do not want to be bother with taking the time a smaller battery would make more sense. It would take less time to recharge and when it goes bad because of poor maintenance it will cost haft as much to replace it.

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    Battery bank storage should be determined by the expected demand and desired duration and by the ability to recharge effectively. Most of us who use battery power have figured out what works for our own needs. Keep in mind that golf car batteries are 6v so you'll need to hook them up in series to get 12v. No big deal, most off-grid batteries are 6v and wired in series or series-parallel as needed. A single marine deep cycle battery may work well for low demand. That's how I got started. Now I have a much bigger battery bank, flooded, and it requires a much bigger charger and therefore a bigger generator to power it. There are lots of variables. Start with the demand/recharge thing. Let your system morph into something bigger as your requirements change.

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