solar power supply

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solar power supply

Postby dolabra » Fri Oct 05, 2012 11:18 pm

I wanted to make something tonight, so I threw together a little something. It is a solar garden light turned power supply. It runs off a single AAA and boosts to 5v with a NCP1402 breakout board. Everything was from stuff I had laying around. I broke all the rules -- I soldered directly to the battery and I'm recharging an alkaline. I'm surely going to be sent to prison for this. The picture shows it charging a little bluetooth keyboard. It won't charge my phone, the thing only produced 200mA or something like that. I'll keep it in a sunny window. It might be handy occasionally.
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Re: solar power supply

Postby matseng » Sat Oct 06, 2012 12:12 am

Do you really get 200 mA (@5 volts when boosted) from that tiny panel? That's like 1.2-1.3 watts...
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Re: solar power supply

Postby dolabra » Sat Oct 06, 2012 7:57 am

No. I get 200mA from the boost converter and battery (that's what the spec says, I haven't confirmed it). I don't know what the panel gives, not much. It will take a long time to charge, I intend to leave it in a window and pull it out to test an LED or something :)
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Re: solar power supply

Postby mobilewill » Mon Oct 08, 2012 4:55 pm

I saw the same thing from the dollar tree here in the US for $1. You might want to look for one. I want to get one and hack it. It comes with the solar panel, battery and led. On top of a stake to put in the ground.
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Re: solar power supply

Postby dolabra » Mon Oct 08, 2012 6:45 pm

yeah, that's what it is. The boards in these things are fun to play with. I have never been able to get more than a few mA out of the LED drivers that come with these things. I wanted something a little more powerful, so I replaced the battery and the board with a proper switch mode supply.

I kinda have a fetish for them, I'm always buying them when I see them cheap. But I'm always disappointed that the solar cells are pretty weak.

I've actually used this contraption a bit this weekend; it was pretty handy. Now it needs a couple days in the sun to recover.
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Re: solar power supply

Postby dolabra » Wed Oct 24, 2012 11:00 pm

I gotta say, this is even more handy than I imagined. Now I want a 3.3v version. I haven't decided if I'm going to put an LDO on the 5v output of this one, squeeze a 3.3v SMPS in this one, Or make another with 3.3v SMPS.

Thoughts?
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Re: solar power supply

Postby markr » Mon Oct 29, 2012 10:42 am

Did you try using the original battery that came with it? I have a bunch of dead solar lamps. They work if I charge the battery, but the Texas sun has crazed the covers over the panels; and more importantly the photo-detector.
I'm thinking this could be a good way to use the panels and the batteries.
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Re: solar power supply

Postby dolabra » Mon Oct 29, 2012 3:30 pm

The orig battery was a 1/2AAA Ni-Cad rated at 200mAh. I didn't bother with it. But there is no reason it wouldn't work, just not very long.

I have buffed out the crazed covers on these before, it can extend the life a little.

But, go for it. I did this project as a whim, but it's been extremely handy.
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Re: solar power supply

Postby dolabra » Mon Nov 19, 2012 9:05 pm

3.3V version! I made a second one, this one is 3.3v

This time I made the boost converter. It's a 3.3v ncp1402, using the circuit from the data sheet manufactured by OSHpark.

board 3 001.jpg


Finished product, complete with crappy (free from Harbor Freight) meter that I confessed to own in another post :

2012-11-19_20-53-03_672.jpg


Isn't the switch ridiculously large :)
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Re: solar power supply

Postby andrewsuu » Thu Feb 28, 2013 12:56 am

I have had no issues with this setup and it works as if one unit
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Re: solar power supply

Postby dolabra » Thu Feb 28, 2013 8:38 am

andrewsuu wrote:I have had no issues with this setup and it works as if one unit


Thanks. I'm as happy as can be with this setup. I keep them in a sunny window and pull them out when I want a little portable power. I haven't had any trouble with the batteries over charging.
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Re: solar power supply

Postby AllanLee » Fri Nov 08, 2013 11:16 pm

markr wrote:Did you try using the original battery that came with it? I have a bunch of dead solar panel. They work if I charge the battery, but the Texas sun has crazed the covers over the panels; and more importantly the photo-detector.
I'm thinking this could be a good way to use the panels and the batteries
.

Yes it nice way of using battery and solar panels.. I am using it in similar manner and got really good outcomes
Last edited by AllanLee on Mon Nov 11, 2013 10:29 am, edited 1 time in total.
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Re: solar power supply

Postby stryker » Fri Nov 08, 2013 11:46 pm

markr wrote:...the Texas sun has crazed the covers over the panels; and more importantly the photo-detector.
I'm thinking this could be a good way to use the panels and the batteries.
I've found toothpaste does a good job of buffing them back to shiny functionality. Not sure whether 'minty fresh' is a bonus but it is a side benefit of the approach...
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Re: solar power supply

Postby dolabra » Sat Nov 09, 2013 10:56 am

My 5v version did overcharge in the summer sun and the battery released some electrolyte (tiny amount that corroded the wires). I replaced the battery with another alkaline I had lying around, it would of course be better to use proper rechargeable batteries (oh well). I may need to replace the switch on that one too, the contacts in the switch seem to be corroded.

All and all a successful little project, handy source of power
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