12 volt barn light wire

I am putting 4, 12v --27 watt LED lights in a remote barn. They will be powered by a 12 v battery and solar panel charger. Question: the 4 lights are 8, 10, 20 and 30 feet from the battery. Can I use solid copper regular 12ga. house wire for this and will that reduce the voltage drop versus stranded wire?

Also, any idea how long the lights will operate on a fully charged 100 amp deep cell battery?

Thanks

To answer part of your question, stranded and solid copper wire of the same gauge carry the same amperage of DC current.

That 12 gauge wire should work just fine. It is rated at 20amp at 110 volts so it should be over kill for that

Solid will be a pain to work with . Solid is best used in pipe.Same gauge same ampacity.

That battery should be more than sufficient to power those lights. If I am doing the math right all four of them together will draw less than 2 amps.

I have a similar set up in my tractor shed that uses a solar powered garden light setup. It has a very small solar panel that recharges a battery pack. That battery pack only contains 8 rechargeable AA size batterys. It runs three small LED lamps (not sure of wattage) that turn on at dusk and go off at dawn. I don't know if they actually run all night or not (I have never checked them at dawn). Its not terribly bright but I can see my way around in the shed if I need to find something at night. It has been working for about 5 years now without failure.

12 into 27 is 2 25 amps per fixture. 4 lights need 9 amps. 14 gauge would save a few dollars and be ok

Oh! you are right - I divided the 12 and the 27 the wrong way. Thanks for clarifying that.

Hay hay, lets do the math in order to answer your questions:

1) "I am putting 4, 12v --27 watt LED lights in a remote barn."
That's 108 total watts and at 12 volts that's 9 amps of current draw.

2) "Question: the 4 lights are 8, 10, 20 and 30 feet from the battery.
Can I use solid copper regular 12ga. house wire for this"
SURE but I prefer stranded wire a) for the added flexibility and ease of installation b) you only need 2 conductor twin
lead versus 12/2 with Ground typical 3 conductor Romex house wiring. Id compare prices from 12/2 Romex versus 12/2 twin
lead.

3) "and will that reduce the voltage drop versus stranded wire?
NO 12 gauge is still 12 gauge wire
I dont forsee any excess voltage drop problem with using 12 gauge wire over a relatively short 30 foot run at 9 amps.

4) "Also, any idea how long the lights will operate on a fully charged 100 amp deep cell battery?
YES I have an idea plus will calculate an approximate answer:

The lights will draw 9 amps and your battery is rated for 100 Amp Hours. I don't recommend you discharge your battery
over 50% of its rated capacity (actually I don't like to draw down over 30%) THEREFORE I would figure you have 50 Amp
Hours available. 50 Amp Hours (capacity) divided by 9 amps for all 4 lights = 5.5 hours of use to discharge the battery
to 50% of its capacity BUT I DONT LIKE TO DRAW MORE THEN 30%, do as you please.

NOTE FOR BILLY BOB AND BUBBA These are only quick and dirty approximations, may NOT be exact, I could calculate them given more battery info SO NO WARRANTY. As battery voltage drops from 12.6 down to 12 or so, current will change so the exact answer may be different.

John T Got it??? Any other questions???

I would add, the bigger your solar panel the better. More so in the winter. Colder weather and much shorter days. Optima blue top deep cycle battery would be a dream!

Hey John T go to allis forum down to hard starting WD. Tell me If I have lost my mind.

I would stick with the #12 wire. The voltage drop in 30 ft. of #14 wire is going to be around 1.4 volts at your last light. If I did that correctly.

I did it go take a look. NO I think you still have your mind and I am of the opinion YOU ARE RIGHT AND OLD IS WRONG

John T

Many thanks. Won't need the lights in summer when it is daylight until 9 Pm.
I think it will be rare to use the lights more than 1 hour per day to feed and check on critters, so the battery should last 2 or 3 days even on rainy days with no sunlight.

I was concerned about voltage drop. But flexible stranded wire will be easier and cheaper.

great info. Ciao!

You will need a charge controller. It goes between the solar panel and the battery. Get a Stella made in Germany. The terminals are marked, Two for,panel,battery and load. It will shut off the load automatically if the battery gets too low. It is also temperature compensated. It lowers the charging rate as the ambient temperature goes down to protect the battery from gassing. So, a warmer location for the battery is best. You should be able to find one on e-bay.

Thanks to all, I have ordered a charge controller, will use 12ga wire.