How to put color LED Bulbs in Solar Garden Lights?

[CornMan]

I'd like to take the boring white LED bulbs out of my solar garden lights and replace them with colored LED lights. Anybody done this?

[trilobyte]

It probably varies widely on the make/model of what you're using. Most that I've seen aren't user replaceable. If that's the case, my recommendation is to leave the white in and cover it with a color gel. A few bucks per sheet, and you can easily cut to size and probably cover all your lights.

[CornMan]

I didn't imagine they'd be replaceable by just pulling them out. I figured I'd have to carefully cut the wires and solder the colored ones in place.

[SnowBlind]

LEDs have something know as the forward voltage. This voltage is dependent on the particular LED you are using, but they tend to be related to the color. Generally, Red, Orange, Yellow and Green tend to have lower forward voltages (1.6V - 2.2V), while Blue, Violet and White tend to have a higher one (2.5V - 3.7V). Note that individual models can be different, and high brightness LEDs can be higher.

Any circuit designed to drive an LED has to be setup so that the right forward voltage drops over the LED, otherwise you are driving it with too little or too much current. There are different ways to drive LEDs, the simplest being a current limiting resistor. The solar garden lights I've looked at did it that way, but some models could be more sophisticated.

If you replace the LED with one with a similar forward voltage you should be fine. If it has a different forward voltage, you could be over-driving it and possibly burn it out.

Without knowing anything else about the circuit, it's hard to tell, but I would think you might have a better chance replacing the white with a blue LED than one of the other colors (Red, Orange, Yellow, Green). If the circuit simply uses a resistor, you could of course replace that with the appropriate valued resistor for the LED you are using. Or you could simply try it out and see how long they hold. It's possible that you are over-driving a red LED, but it will live long enough for the burn.

[BBadger]

Here's the deal with solar garden lights:

The circuit isn't like those simple battery + LED + resistor circuit that you have to set to a specific value to work. The solar panel and the battery don't provide much voltage, but the white LED needs a higher voltage to work. So the lights have an oscillating power circuit in there that converts the low-voltage from the battery to a sufficient voltage for the LED, along with some current. It's relatively efficient, which is definitely needed for those solar lights.

What does that mean for you? You'll just have to see if it works by experimenting. The circuits can usually "auto" adapt to the different voltage drop from the color-changing LED. So there's a good chance the auto-color-changing LED might just be a drop-in replacement for the white LED. Whether it uses more power or all the colors of the lights work... well, you'll just have to see.

How to do it? Rewire the white LED with the color changing one.

For myself, I'd probably end up just building something that would do the same thing because those solar garden lights are relatively expensive for what you get. It gives me an excuse to buy a bulk amount of parts too.

[junglesmacks]

Paint the bulb with fingernail polish or markers.

[disco_duncan]

I'd like to take the boring white LED bulbs out of my solar garden lights and replace them with colored LED lights. Anybody done this?

LED's are pretty robust devices and you've got to work hard to zap them! I have seen them massively over-driven and still working.

I've just taken one of my lamps apart and it has a very crude regulator between the solar cell and the LED. LED's are polarity sensitive so you have to solder them into the circuit board the right way round. If you look inside of the plastic LED envelope the lead that ends with a bigger metal tab is usually the Cathode which has to be connected to the negative supply. Often the cathode is also the shorter lead. Before you unsolder the original LED check which is the cathode using the same method.

Good luck!!

[BBadger]

Paint the bulb with fingernail polish or markers.

Oh come on man, you--of all people--should know that putting filters on your lights is far less effective than going with chromatically pure light sources to begin with. Filters are what you use on hot stage lighting because you have 300-10,000 watts of power at your disposal. Solar garden lights? They're dim as shit already. They need all the help they can get!

With all the LEDs available cheaply it would be a disservice to the effort of even modding these lights not to use the actual LEDs that produce the specific colors--not those dumb LEDs that just incorporate their own filters. Hell, even if it doesn't work, it's worth the effort to see if they do.

On another note, I misread the OP about the lights. I thought he meant those auto-color changing LEDs, not just colored LEDs. I need to see if those will work in those garden lights. I'll have to try them out and see if they do work.

[Elorrum]

I put some RGB slow change leds in garden lights. In the single led, single battery, garden lights, the colors don't change... there are three colors showing at one time. In the two battery, two led garden light, the colors do change. Either one is sort of cool. The boards on both had good graphics indicating which hole was positive. In the two led garden light there is a bit of a short, so I can wiggle one of the leds to get them to change out of synch, which makes some cool colors.

[junglesmacks]

Paint the bulb with fingernail polish or markers.

Oh come on man, you--of all people--should know that putting filters on your lights is far less effective than going with chromatically pure light sources to begin with.

Lol.. busted.

I do and you're absolutely right. That was an off the cuff early AM answer. I, too wonder about the mod factor of those. Keep in mind that the only colors that you would theoretically be able to swap out that white LED for would be a green, blue or pink.. due white LEDs being typically a 3.2v unit. Red, yellow, amber and purple are all around 2.2v.. so I would imagine that there's some type of limiting circuit/battery/whatever that's putting out as close to 3.2 as possible. Or.. it's less due to the constant dimness of those things and maybe.. just maybe.. you'd drive the shit out of some red LEDs and actually make them bright!

Rip one apart and do it! Let us know.

[CornMan]

Thanks for the ideas. The color changing ones at Harbor Freight are $3.33 apiece, and I like those, but I'm really on a budget. I see that Radio Shacks colored LEDs start at 68 cents.

[disco_duncan]

Thanks for the ideas. The color changing ones at Harbor Freight are $3.33 apiece, and I like those, but I'm really on a budget. I see that Radio Shacks colored LEDs start at 68 cents.

Keep a look out for constructors packs. You can get a big bag of various colours for not much cash!

[BBadger]

I do and you're absolutely right. That was an off the cuff early AM answer. I, too wonder about the mod factor of those. Keep in mind that the only colors that you would theoretically be able to swap out that white LED for would be a green, blue or pink.. due white LEDs being typically a 3.2v unit. Red, yellow, amber and purple are all around 2.2v.. so I would imagine that there's some type of limiting circuit/battery/whatever that's putting out as close to 3.2 as possible. Or.. it's less due to the constant dimness of those things and maybe.. just maybe.. you'd drive the shit out of some red LEDs and actually make them bright!

Reading about the circuit, I think the voltage just adapts to whatever the voltage drop is of the LED. I'm not sure about the current, but I'd mostly be worried about the lifetime of the battery, and whether it uses up too much juice during the night. As for the LEDs, I think they'll last. As a kid I remember driving those ultrabright red LEDs directly from 9V batteries, so they're pretty hardy.

Thanks for the ideas. The color changing ones at Harbor Freight are $3.33 apiece, and I like those, but I'm really on a budget. I see that Radio Shacks colored LEDs start at 68 cents.

Get some cheap-ass ones from eBay. I bought some for BM bike decorations but ran out of time to use them last year; however, I was able to use them for some jack-o-lanterns. Here's the seller I got them from ($7 for 25; $18 for 100). They come with free resistors which are probably the wrong value, but hey, they're free!

Give them 3.0-3.2V of voltage and about 20mA or less of current. I used a 4V supply with some cheap 47-ohm resistors in my setup and it was perfectly bright at night. What I'm not sure about these is whether they'll actually change colors with that oscillating circuit. Worth a shot. I'll see if I can get some of those garden lights and test it out.

Finally, you might consider just making your own solar lights with parts. They're essentially Joule Thief-type circuits. For the cost of some cheap-ass ferrites, some cheap electrical parts (they're at the same site), an LED, and a battery (go all-out and buy a D-cell and you'll last all week) you'll have something that lasts a looong time. You could also make it solar charging if you want, but it might not be worth the extra cost. It'll probably cost you less than those solar garden lights, which usually contain the same thing, but at $5 more each. You can order the parts from Mouser.com or Allelectronics.

[junglesmacks]

I was in WallyMart the other day and they had them for $0.99..

[BBadger]

That's pretty cheap. I've only seen them for like $5-7 or so.

[SnowBlind]

I do and you're absolutely right. That was an off the cuff early AM answer. I, too wonder about the mod factor of those. Keep in mind that the only colors that you would theoretically be able to swap out that white LED for would be a green, blue or pink.. due white LEDs being typically a 3.2v unit. Red, yellow, amber and purple are all around 2.2v.. so I would imagine that there's some type of limiting circuit/battery/whatever that's putting out as close to 3.2 as possible. Or.. it's less due to the constant dimness of those things and maybe.. just maybe.. you'd drive the shit out of some red LEDs and actually make them bright!

Reading about the circuit, I think the voltage just adapts to whatever the voltage drop is of the LED. I'm not sure about the current, but I'd mostly be worried about the lifetime of the battery, and whether it uses up too much juice during the night. As for the LEDs, I think they'll last. As a kid I remember driving those ultrabright red LEDs directly from 9V batteries, so they're pretty hardy.

There are definitly circuits (or ICs) that act as a constant current source, in other words, no matter what the forward voltage is, they will adjust the voltage so a particular, defined current is running. They have the additional advantage that as the battery gets lower, the brightness stays the same. With those you can swap the color of the LED and it should just work. Some garden lights might have those. Simpler ones have only a resistor.

[BBadger]

Actually all the solar garden lights have those chips, because the NiMH/NiCad rechargeable battery and solar panel don't provide enough voltage to run the LEDs. It'd actually be more expensive to provide a higher voltage source and the solar panels to provide that voltage. They do go cheap on the "inductor" by using a resistor though (see below).

I just recently bought some cheap-ass $2 solar lights at Big Lots to see how they work, and they all have QX5252-based circuits in them. All it is is a cheap boosting circuit that kicks the voltage high enough to power those LEDs. The manufacturers go even cheaper and use a low-valued resistor instead of a pure inductor to set the current.

As an experiment, I went about trying to swap out the LED for a color changing one. While it lights up--dimly--it doesn't change and would be useless for lighting. I think it's a limitation induced by the resistor in the circuit though, so I'm going to see if I can find some inductors to replace the resistor with. Those little chips can be programmed to supply nearly 800mA or so I believe, which is pretty amazing considering how small and cheap they are. Inductors from Mouser run about $0.30 to $0.60, so it is entirely feasible to get these things working with any LED at a specific current for cheap. Also there are other chips that you can buy to just outright make your own long-lasting LED lighting circuits from low-voltage power sources.

The garden lights use those cheapo NiCad batteries, but with the charging cycle of solar lights it may actually be a good battery for that kind of thing.