Camp Perimeter Lights - Battery/Solar Powered

[Corster]

Hey everyone, we are looking to add perimeter lights to our camp, preferably in the form of LED rope lights powered by a battery. We would also like to be able to charge this battery from a solar panel if possible (no generator at our camp). We are looking to light a 300ft perimeter.

Does anyone have suggestions for how this could be accomplished? I have been looking into powering 2x 150ft LED Rope Lights from one or multiple car or marine batteries. Is this possible or is it silly to assume that we could recharge this large of a battery from a modest solar panel?

[Popeye]

This has been discussed many times. Look in the links at the end of this thread. After you have read them come back and ask any further questions.

[some seeing eye]

Hey, welcome to ePlaya!

Start with the the load in Watts. That depends on your specific LED strip. Multiply by hours. Divide by battery draining capacity - say to 1/2. That's your battery Watt hours. (Most batteries don't like to go below half drained)

Batteries are often in Amp hours. Watt hours divided by volts = amp hours.

Solar panels at the right angle and directions have a peak Watt output. Multiply the peak Watts at orientation by the insolation https://www.emarineinc.com/Sizing-Your- ... lar-System. Make the peak Watts times insolation greater than or equal to the amp hours needed in a day.

So it's a 2 part problem. The draining the battery part and the charging the battery part, in that order.

Say 300 Watts at a Watt per foot x 10 hours drain = 3000 Watt hours. 1/2 battery derating = 6000 Watt hour battery. Divided by 12 V battery voltage to half fill = 250 Amp hours. That's a several batteries. 12 V lead acid deep cycle batteries are about $2-3/Amp hour. They weigh about 80 pounds for 100 Amp hour

3000 Watt hours to go from half battery charge to full divided by 4.5 insolation is ~700 peak panel Watts. That's about 2-4 rooftop panels each about 50 pounds and will cost $.50-$1.00/peak panel Watt.

You will need a charge controller, wires and fuses and spare fuses, maybe an inverter and a bracket to hold the panels at the right angle. That's ~$100. As you can see, the lower the Watts load the cheaper the system.

Check my math. It's not guaranteed.

[WileE13]

Make it easy on yourself, go buy LED string lights that are already attached to a small solar panel and made for this exact purpose.

[rodiponer]

Check my math. It's not guaranteed.

I checked it with my own vague rules of thumb. I think you're about right. I came up with about $2,300 for a solar system.

Here's a Google Doc spreadsheet of my math.

I am some shade of environmentalist, and so have a natural enthusiasm for solar systems. But for a 1 week/year system like this, I'm conflicted because batteries need love for the other 51 weeks of the year. Or they die and become a couple hundred pounds of lead and plastic that has to be recycled. It's not hard, but not something I feel can sit unattended in a garage or storage unit and work well, year after year.

So I'd like to add that a small and quiet Honda 1000 generator is $800, and with a suction-siphon hack to make it draw from a larger outboard gas tank, could run for days. A Honda 2000 is ~$1000 and would run all night, or nearly so. Even more nerdy is to buy a propane conversion kit, for a long runtime and super reliability (because the carb won't clog up from old gas between years). I haven't done the math, but transporting ~400 pounds of battery and solar panels will consume gas, and these small suitcase generators will probably only eat ~1 gallon/day at this low load.

What makes this expensive is that 300' of 1 watt/foot rope yields a pretty high load for a solar system to sustain for 10 hours. I think that with good choices and nerdery this could be cut by an order of magnitude, making the whole solar system a lot less expensive.

My father in law helped me wire up Aluminipede, and he made a home made LED dimmer that exploited the gooey chemical cocktail that is our eyes. He said that our eyes are peak detectors that will see a series of bright pulses, separated by a long time of darkness, as a brighter light than a continuously on LED that's less bright than short flashes. He made a circuit that overdrove the LEDs and made them look insanely bright, with about a fifth of the power consumption. The LEDs weren't damaged because they were mostly off and didn't overheat. He did this with an old timey controller, one of those ones you code and C and flash with a plug board, but an Arduino or whatever could do it. So, I don't know, with that and a reasonable house battery in an RV (and genset and battery charger to run incidentally every day for sparkle ponies who need their afternoon hours of AC), the outlay for powering this 300' of rope light overnight could maybe be cut down to ~<$40 in electronics.

[Corster]

Everyone, thanks so much! Really appreciate the breakdown of how to calculate the load and charging!

[legionvr6]

Depending on the load the LED light will create you may be able to go with 12V LED string lights and run them off the load output on the solar controller. That will save you from over discharging the battery and if you get the right controller (with a timer setting) you can have the lights turn on when the sun goes down and then turn off when the sun comes up.

You can build a small solar generator for around $200 (photo of my build attached just missing my panel)