Dangerous Prototypes

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

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 :)

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.

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.

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?

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.

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.

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.

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

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Isn't the switch ridiculously large :)

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

[quote author="andrewsuu"]I have had no issues with this setup and it works as if one unit[/quote]

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.

[quote author="markr"]Did you try using the original battery that came with it? I have a bunch of dead solar panel (http://http://www.shinesolar.net). 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.[/quote]
Yes it nice way of using battery and solar panels.. I am using it in similar manner and got really good outcomes

[quote author="markr"]...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.[/quote]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...

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

[quote author="mobilewill"]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.[/quote]

Hello,

Can you please tell me how to set up the solar power system??