# Rechargeable LED solar lights for garden



## tb2776 (Apr 10, 2005)

I just bought a 4-pack of rechargeable solar LED amber-colored garden lights. Their brightness and light output levels are low-to-average, but I'd like to bump their level up to provide more walkway and garden coverage. 

If I replace the stock rechargeable NiCd batteries with ones that have a higher mAH (like 1000 mAH), will I get more light output? /ubbthreads/images/graemlins/help.gif


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## lambda (Apr 10, 2005)

Probably not any brighter, maybe longer running. Using larger batteries depends on any 'excess' charge capacity the solar cells might have. They might not get any more charge than the stock ones, or maybe more. Best way is just test a modded one side by side with a stock one and see what happens.

Easiest to mod solar lights are those that use three cells. Then you have enough native circuit voltage to run a white LED. To brighten yours you would need to find better LEDs, or use DC/DC circuit, but that would also shorten run time.


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## VidPro (Apr 10, 2005)

amber leds would still be ok, but they need at least a lux1 in them if you ask me  and of course a 1W solar cell.
because the size of the solar cell would have to be about 4x5 minimum to get some batteries charged for it, i gave up on the idea myself.
with 2x 2500nimhy, and a 1W solar cell, it might get a run time of 5 hours, after a good sunny day.

i was told that they dont last the whole night after a charge, changing the batteries isnt going to increase the power going to the led, and if it did, the led wouldnt last long anyways. (bad to overdrive leds, good to run more underdriven)

then you still need to put a better solar cell in them.

analize the present solar cell, if it will not CHARGE better batteries , then it is not even going to extend the time, let alone be any brighter.

if the solar cell puts out 30ma then even on the best of sunny days that would be 480Ma , well under the battery size.
if the led is using 30ma , and you had a Long summer and a good position for the light, it might finnally charge the batteries fully, because it didnt drain them in the short night.
BUT
knowing what stuff they probably put in them, changing the batteries surely wont hurt them 

IF the solar cell will (magically) charge some better cells, then the way to increase the USE of the power aquired in the cells would be to ADD in more leds to the light, if its amber than its a 2.2V gate type led, so you would want to use the same type, amber yellow or red.

if you go to 3 batteries, and WHITE leds (as discussed) you get the advantage of phosphors , and lose the advantage of reduced power consumption because of limited bandwidth output (single color short spectrum). 

its very likely that the solar cell will still be to small power, or that it wouldnt even charge 3x cells.

(ok before i get all windy here)
WHAT IF
you just toss in a coupla more amber leds of the same type into it, increase the ouput and kill the run time?
it shines 2x as bright, no overdrive, and dies (barely visable) 3 hours into the night.


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## WildRice (Apr 10, 2005)

realistically, solor lawn light have a LOONNNG way to go before they replace the 12V underground wired systems. I have replaces my 12V bulbs with 'liberty lights' (my own failed ebay money maker). a PC board with 2red 1 wht and 1blue, looks nice but more of an accent than a usefull light. The only LED lawn light (again 12v) that is close to usefull ( that I have made) has 6 SMD whites, ends up being about 1/3 to 1/2 the brightness of a 4w bulb. To get usefull light from solor lawn lights you need way more power, in and out. A 1w star would work (underdriven), I have aquired some 1/2W samples in amber, these would work, of even a few (2-3) super-flux LEDs (50-60mA each). But this would fully discharge the batteries in under 2hrs (prob).
It it the present day trade off, output for runtime. One OR the other, saddly /ubbthreads/images/graemlins/frown.gif not both.
Jeff


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## yuandrew (Apr 16, 2005)

If you replace the stock batteries with higher capcity ones, they'll last longer

I have a pair of Malibu Solar Lanterns (LZ177-HK) that use one battery and some sort of Dc-Dc converter to drive a single white led. They start out bright but then gradually dim out over the next 4 hours but stay on and give enought light for you to see once you're dark.

They make brighter ones as well. Model LZ 310 is one of their largest ones and uses a 1 watt LED (Luxon?). That's the first time I've heard of a 1 watt led used in a solar garden light.

Their best ones use 4 Ni-MHs and a CCFL. LZ301 and LZ10006 are the CCFL models

http://www.intermatic.com/images/catalog/groups/2004-TS89_Malibu-LZ.pdf


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## Lynx_Arc (Apr 16, 2005)

I haven't figured out why people just dont make 12v LED wired lawn lights. The amount of money spent on solar lights that dont work well compared to the electricity saved doesn't sound worth the trouble. If you wanted to go solar then wire up a larger cell to charge a 12v SLA instead of all the smaller cells charging wimpy AA cells. The amount spent on seperate circuits for each light could be pooled into cabling costs and larger solar cells without circuitry for each light. If you had 3 5mm LEDs at 30ma each per light times 10 lights you would be running 300ma at 12v or about 4 watts of power which is nothing on an electric bill compared to leaving a 40 watt light on all night instead.


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## WildRice (Apr 16, 2005)

There are LED plug0ins for malibu lighting, but the price is really up there, for 9 LEDs, a pc board and some components. Easier to make your own.
Jeff


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## Ken_McE (Apr 18, 2005)

*Make Your White More Efficiently*

>The only LED lawn light (again 12v) that is close to usefull ( that 
>I have made) has 6 SMD whites, ends up being about 1/3 to 1/2
>the brightness of a 4w bulb. 

The white LEDs are basically blue LEDs with a phosphor coating. The coating whitens the light but you get less total lumens out. What if instead you took one red, one blue, and one green and mixed the output to get white? I haven't run the numbers but I think you might get more total lumens per watt.


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## Lynx_Arc (Apr 19, 2005)

*Re: Make Your White More Efficiently*

The biggest problem with doing the RGB is again you are using a blue LED in the equation. Matching the vf of the 3 LEDs and outputs to attain proper color is more of a hassle than just using several white LEDs. You would either have to use a reflector or several groups within each light to spread it around. What I wish I could find cheap is sockets for 5mm LEDs. That way you can pull out one and put a new one in with no soldering.


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## WildRice (Apr 19, 2005)

*Re: Make Your White More Efficiently*

In a 12vac confiruration, it works really nice. B(3.6v),R(1.7v), G(3.1v) = 8.4v add a resistor to limit total current to 25mA, and add a second string in the opposite current flow (total of 6 LED's). Main problem with RGB in a lawn light (unless you want it ) is mixing to get a nice white. The PCBoard I made has 2 whites on each flat side and 1 in each edge, real simple for wiring (i'll try to post a pic of 1 here). 
It all depends what you are looking for, for accent lights (white or color) LED's are great, although after about a year of having my 'liberty lights', red,white and blue plug ins in the field (my yard) I can see some of the LED legs rusting. Something like this would need to be tinned and/or laquered to protect from the elements.
Jeff





This one is one of my white Malibu replacements. 2 sets of 3 series SMT whites with 100ohm resistor in an opposing parallel connection.


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## Lynx_Arc (Apr 19, 2005)

*Re: Make Your White More Efficiently*

One advantage in the rgb format is if you resistor them seperately and run wires for each color you could have neat moodlights in your yard... adjusting the 3 colors could be fun or have some sort of random oscillation of the colors making psychadellic sort of colors..... yes... drive your neighbors crazy with yardlights... /ubbthreads/images/graemlins/grin.gif


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