# Solar lighting for sheep barn - help!!



## YuccaFlatsRanch (May 3, 2004)

I have a 3.5 watt solar panel (from a VW jetta) and a 12 volt battery and plan to purchase one of the 27 LED 12 volt lights from Ebay. The 27 LED bulb uses about 2.5 watts. If I connect the 12 volt LEDs to the battery and the battery to the solar panel will the panel keep the battery charged so the lights run all day and night and I don't have to worry about putting a light sensing switch on it?? It seems like an easy way to accomplish lighting in my outlying barns.

Looking at the system 2.5 watts out and 3.5 watts in should work with the extra watt pretty much making up for the loss at night. I could also just install a manual switch in the system since I go to each barn both A.M and P.M. to feed.


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## wy_white_wolf (Oct 14, 2004)

No, Your usage would be 60 watts a day (2.5*24) while your production would only be about 17.5 watts (3.5*5). You need to get your panel up into the 15 to 20 watt range to work and handle the charging losses.


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## 12vman (Feb 17, 2004)

How long do you plan to use the light at any given time? 

I figure for every hour of charge time, the light would be supported for an hour. (Leaving the extra watt for battery losses)

Setting the panel at the proper angle, you should collect at least 4 hrs. of run time in a good day. Forget the extra watt from the panel. This will cover the normal losses in the battery. (And a fraction more)

Don't go too big on the battery! Maybe consider a 12 volt battery pack (Nickle Metal Hydride) from a cordless drill @ around the 2000mAh range. This would assure the battery could achieve at least 1/2 charge capacity on a good day. (2-day reserve) This is assuming using a switch, only using when needed, 4 hour usage a day. (Max)

WWW is correct. If you plan for the light to operate 24/7, you would need a larger panel and more battery..


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## YuccaFlatsRanch (May 3, 2004)

I use the light to light the barn at night so the animals have light to eat. 

IF I could find a smaller bulb I would use it as the light doesn't have to be too bright. How long should a 12 volt deep cycle battery last between charges with this light bulb running 12 hours per night and getting a charge from the panel during the day. I also have a 5 watt panel.

How would I go about using a NIMH battery from a drill in this application??

Maybe I should just use one of the solar kits with the 4 spotlights to accomplish the lighting. Each of the spots has 2 LEDs and would provide plenty of light. Hard to believe the tiny batteries in this system would work better with the tiny solar panel provided than a 12 volt deep charge battery and one 27 LED light though.


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## 12vman (Feb 17, 2004)

Yucca.. About the drill battery.. Sometimes I get ahead of myself and figure everyone can solder. Sorry.. Me Bad! 

There's two contacts at the top of the battery somewhere to solder to. I've used them a few times on small projects. Many times it's cheaper to buy a complete battery than to try to build one yourself..

Quote:
"I have a 3.5 watt solar panel (from a VW jetta) and a 12 volt battery and plan to purchase one of the 27 LED 12 volt lights from Ebay. The 27 LED bulb uses about 2.5 watts."

"I could also just install a manual switch in the system since I go to each barn both A.M and P.M. to feed."


This is what I based my post on. If ya wanna do an all nighter, We'll need to look at things again. Decide on what lights you want to use..

Quote:
"Maybe I should just use one of the solar kits with the 4 spotlights to accomplish the lighting. Each of the spots has 2 LEDs and would provide plenty of light. Hard to believe the tiny batteries in this system would work better with the tiny solar panel provided than a 12 volt deep charge battery and one 27 LED light though."

The issue here is you wouldn't be working the battery enough and over time, The eletrolyte would stratify. (Seperate) Using a combined 8.5 watts of panel wouldn't provide enough current to boil the deep cell battery to keep things mixed up. (The Electrolyte) The cycles would become shallow and the battery would be ruined..


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## YuccaFlatsRanch (May 3, 2004)

I found another LED light with 12 bulbs that says it uses 80mA per hour. If my math is correct then its wattage is approx 1 watt. Assunimg this is correct can I run this light as I want to using the 3.5 watt panel and have the battery not run down too badly - I can charge the battery on my charger every once in awile if necessary.


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