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VERY small scale solar lighting system

Posted by jll0306 (My Page) on
Fri, Sep 26, 08 at 17:19

We have a small woodstove which could serve for heating and cooking in the event of power outage, but it would be nice to have electric lights for a while at night. I'm trying to design a very simple solar system, which chargs a small battery during the day that I bring in to power a 12v. light at night.

I have the following components but I have not hooked everything up yet.

One 15 w. solar panel,
One UB1250 12v, 5 ah sealed led-acid battery
One 12 v., 15 amp solar charge controller
One 12 v., 9 watt Coleman work light

My hub thinks this is a great plan, but he is math/techno phobic, so he can't help. Am I on the right track here or should I back up and start again?

Assumption 1. 5-6 hours of sunlight will be sufficient for initial battery charging (6 x 15 = 75 w)

Assumption 2 Use of the solar charge controller between the panel and the battery will protect the battery from overcharging.

Assumption 3. I do not want to discharge my battery deeper than 50% at any sitting. Therefore, I should plan on using the light only 3 hours a night.

If those assumptions are correct, I have three questions:

1.How much power loss can I expect in a 12 volt system?

2. Where can I find a 12v. socket to connect to the battery?

3. Is the sealed lead acid battery the best choice?

thank you for any help you might be able to give me!

j.


Follow-Up Postings:

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RE: VERY small scale solar lighting system

Oh, Gary, thank you so much. I may have overcharged my battery on my test run, before i knew about needing acharge controller, so I'll check out alternative batteries while I' shopping for a female 12v. cigarette lighter socket.

I really appreciate the feedback and the link.

j.


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RE: VERY small scale solar lighting system

thanks, SolarJohn.

I have another 12 v, 5 ah "regulated valve" (whatever that means?) battery from a backup power supply for a computer. If I can use it, too, then I can always have a charged battery/light combo hooked up and ready to go inside the house while the other battery is charging outside.

So, guys, if you have a moment, could you help me through the next part??

The solar panel was part of a "emergency solar power kit" that came with the connector cable, battery, and an DC/AC inverter.

The solar panel power outputs are embedded in 1" square white tab plug-in on the panel edge.

The panel-to-battery connector cable is a single white wire with a similar square tab plug-in connector on the panel end and a single barrel connector on the battery end.

The matching barrel connector on the battery is soldered to the negative terminal. A two inch wire terminated by a black rubber nut looking thing also comes out of this connector, but it is not connected to anything. I don't know if this barrel connector contraption is supposed to be soldered to the BOTH connectors and broke off in shipping, or if it is just supposed to hang out there in space, but that's probably NOT important since I don't want to use it.

If I leave the square tab on the panel end but strip that barrel connector off the battery what are my odds of finding marked black and red wires inside the white wrapping that I can match to the +/- poles of the charge controller?

BUT if they aren't marked, what do I have to do to figure out which is which?

Thanks again. I think this may be the last of the dumb questions, but I won't guarantee it.

J.


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