Query - solar power and electronics project

[[email protected]]

Hi,

I would like to build a solar powered light for the interior of my
garage (I know I can buy these but I've got hold of a solar panel and a
luxeon LED and thought it sounded like a good idea).

I have got a blocking diode going to the +ve end of the solar panel (to
stop it draining at night) and the solar panel is attached to 4 x 1.2V
rechargable batteries.

I can attach the LED (with a resistor attached) ok to the +ve and -ve
wires and it does come on (very bright). However I would like an on
/off switch so the light is not permanently on.

I have attached 2 more wires going from the batteries (so there are two
+ves and two -ve wires attached to the battery):
One wire comes from the battery goes straight to the correct end of the
LED, then from the other connection of the LED there is a wire to a
SPST switch. A wire then goes from the switch back to the battery.

I've tried this however the LED doesn't come on this time, does anyone
have any suggestions to a newbie at electronics please?
Thanks

 

[Ian Stirling]

Hi,

I would like to build a solar powered light for the interior of my
garage (I know I can buy these but I've got hold of a solar panel and a
luxeon LED and thought it sounded like a good idea).

I have got a blocking diode going to the +ve end of the solar panel (to
stop it draining at night) and the solar panel is attached to 4 x 1.2V
rechargable batteries.

I can attach the LED (with a resistor attached) ok to the +ve and -ve
wires and it does come on (very bright). However I would like an on
/off switch so the light is not permanently on.

Cut one of the wires you had going to the LED when it worked, and insert
the switch.

 

[[email protected]]

Thanks for your prompt reply: I've just had another look at it and it
was just a dodgy wire connection: its working great now.

Cheers

 

[Luhan]

Hi,

I would like to build a solar powered light for the interior of my
garage (I know I can buy these but I've got hold of a solar panel and a
luxeon LED and thought it sounded like a good idea).

I have got a blocking diode going to the +ve end of the solar panel (to
stop it draining at night) and the solar panel is attached to 4 x 1.2V
rechargable batteries.

I can attach the LED (with a resistor attached) ok to the +ve and -ve
wires and it does come on (very bright). However I would like an on
/off switch so the light is not permanently on.

I have attached 2 more wires going from the batteries (so there are two
+ves and two -ve wires attached to the battery):
One wire comes from the battery goes straight to the correct end of the
LED, then from the other connection of the LED there is a wire to a
SPST switch. A wire then goes from the switch back to the battery.

I've tried this however the LED doesn't come on this time, does anyone
have any suggestions to a newbie at electronics please?
Thanks

I had a similar situation. Bought 4 solar powered yard lights from
WalMart for under $20 total. Removed the stakes, rigged hooks using
coat hanger wire, and hung them up in the tree out front. Great yard
lights and the neighbor's kids cant get at them.

Luhan

 

[Jim Thompson]

[snip]

I had a similar situation. Bought 4 solar powered yard lights from
WalMart for under $20 total. Removed the stakes, rigged hooks using
coat hanger wire, and hung them up in the tree out front. Great yard
lights and the neighbor's kids cant get at them.

Luhan

Helluva good idea, particularly for AZ.

Do you have model number information?

...Jim Thompson

 

[Luhan]

[snip]

I had a similar situation. Bought 4 solar powered yard lights from
WalMart for under $20 total. Removed the stakes, rigged hooks using
coat hanger wire, and hung them up in the tree out front. Great yard
lights and the neighbor's kids cant get at them.

Luhan

Helluva good idea, particularly for AZ.

Do you have model number information?

The box may be around here somewhere. Just check the garden section
(indoor) at your local WalMart for the best deal. You can also find
similar deals at Home Depot lately.

The units come complete with a pair of AA nicads, solar cells,
charging/switching ciruit, and a one really efficient LED. You could
not possibly make one for the price they sell at. I have, however,
considered buying them just for the solar cells.

Luhan

 

[Joerg]

Hello Luhan,

The units come complete with a pair of AA nicads, solar cells,
charging/switching ciruit, and a one really efficient LED. You could
not possibly make one for the price they sell at. I have, however,
considered buying them just for the solar cells.

Any idea of the wattage of those solar cells? Are they easy to remove?

Are the AA cells of the solder tab variety? That would be nice because
once in a while one goes down in lab equipment and tabbed NiCd are hard
to find locally, and expensive. Actually it has become very tough to
find any NiCd locally. It's all NiMH and those often don't like 0.1C
trickle charging.

I never liked those stake lights, they don't even come close to a 4W
Malibu light and when I look around the neighborhood they seem to die
quite fast. But for getting at those parts that may be another story. I
guess you could even make a cell phone or radio charger for back-country
hikes.

Regards, Joerg

 

[Kryten]

I investigated solar power a bit:
http://homepage.ntlworld.com/kryten_droid/projects/solar/solar_power.htm
http://homepage.ntlworld.com/kryten_droid/projects/solar/garden_light/solar_garden_light.htm
http://pdfserv.maxim-ic.com/en/an/A0809.pdf

I don't know if the LED is "really efficient" as Luhan said.

Any idea of the wattage of those solar cells? Are they easy to remove?

Mine came in a rain-proof transparent dome.
I could take them out, but then I thought why bother.

Are the AA cells of the solder tab variety?

Mine were not.

NB they need replacing about just over once a year (around 500 cycles).

I don't think they were adequate as illumination, just okay for path
marking.

But for getting at those parts that may be another story.
I guess you could even make a cell phone or radio charger
for back-country hikes.

In the US I expect you can get very far from cell phone masts.
Radio might be nice after a day's hike.
GPS unit and a LED torch might be most useful.

 

[Joerg]

Hello Kryten,

I don't know if the LED is "really efficient" as Luhan said.

So far I wasn't too impressed with LED lighting. A nice halogen bulb is
better IMHO. We have one of those "flashlights" with a car headlight
bulb in there. Really bright.

Mine were not.

Well, if they are at least NiCd that would already help.

In the US I expect you can get very far from cell phone masts.
Radio might be nice after a day's hike.
GPS unit and a LED torch might be most useful.

There is a time delay limit AFAIK. However, in remote areas we still
have analog networks and those can go a long way. A radio is cool. Once
we took a shortwave radio down into the Grand Canyon, only to see how
well you can receive stations from Europe way down under the surface of
the earth. It worked and sure enough a soccer game was on. The ranger
came by to check and walked away shaking her head before we could
explain that this was only a "scientific experiment".

GPS? Nah, I am an old-fashioned map and compass guy. But we did have a
few cold ones in our back packs, only the good stuff, of course

Regards, Joerg

 

[Jim Thompson]

[snip]

I had a similar situation. Bought 4 solar powered yard lights from
WalMart for under $20 total. Removed the stakes, rigged hooks using
coat hanger wire, and hung them up in the tree out front. Great yard
lights and the neighbor's kids cant get at them.

Luhan

I can't determine by surfing... are these yard lights smart enough to
turn off the light and just charge the battery during daylight?

...Jim Thompson

 

[Luhan]

[snip]

I had a similar situation. Bought 4 solar powered yard lights from
WalMart for under $20 total. Removed the stakes, rigged hooks using
coat hanger wire, and hung them up in the tree out front. Great yard
lights and the neighbor's kids cant get at them.

Luhan

I can't determine by surfing... are these yard lights smart enough to
turn off the light and just charge the battery during daylight?

Yep, I got 2 kinds. One has an obvious CS photocell for low light
detection, the others seem to sense directly off the solar cells. They
all don't turn on until its dark enough to notice them.

Generally, they don,t provide much illumination, just act as markers
for sidewalks and pathways. Also, they switch to a lower power mode
to run thru the night if they can't do the time at full power. Not bad
engineering for under $5 each.

Luhan

 

[Luhan]

Joerg wrote:

Any idea of the wattage of those solar cells? Are they easy to remove?

They are embedded in clear epoxy but could be removed as a unit.

Are the AA cells of the solder tab variety? That would be nice because
once in a while one goes down in lab equipment and tabbed NiCd are hard
to find locally, and expensive.

Don't know about you, but I've been soldering onto all kinds of
batteries since I was 10. Buff the ends with really fine sandpaper,
use an 800 watt iron, and just get a dab of solder to stick, then back
off fast. After that pre-tin the wire and sweat solder the two
together. Yep, I'm still here to talk about it!

Luhan

 

[Frithiof Andreas Jensen]

[snip]

I had a similar situation. Bought 4 solar powered yard lights from
WalMart for under $20 total. Removed the stakes, rigged hooks using
coat hanger wire, and hung them up in the tree out front. Great yard
lights and the neighbor's kids cant get at them.

Luhan

Helluva good idea, particularly for AZ.

Illuminated Targets ... ;-)

 

[Frithiof Andreas Jensen]

Any idea of the wattage of those solar cells? Are they easy to

remove?

The garden lights I ripped apart - specifically for the solar cells -
the cells gave out a decent and useful 4V at 20 mA in full sunlight.
The solar cell assembly can be pried off with a knife with a bit of
care - the cells are epoxied onto a PCB that is glued to the lamp with
hot-melt glue.

 

[Ian Stirling]

Joerg wrote:



They are embedded in clear epoxy but could be removed as a unit.


Don't know about you, but I've been soldering onto all kinds of
batteries since I was 10. Buff the ends with really fine sandpaper,
use an 800 watt iron, and just get a dab of solder to stick, then back
off fast. After that pre-tin the wire and sweat solder the two
together. Yep, I'm still here to talk about it!

I find a 25W one just fine.
sand, making sure the sandpaper is absolutely clean.
add a little flux, build up a blob of solder on the iron, and touch to
the battery, back off, leave cool.
Tin the wire, push against blob, and repeat so that the wire sinks
through the blob.
You should touch the cell for a total of maybe 1 second, and it should
be touchable in 5 seconds after you do the joint.