advice needed for solar powered electro luminscent light

System · January 2007

Hi, I'm trying to put together a solar powered electro-luminscent light that uses a rechargeable lithium ion battery. As a way to experiment, I've taken apart an electro luminscent night light that plugs into a wall socket, and tried to hook up the wafer thin light to a 3.6 volt Lithium-ion button battery, however it does not light up. My questions are:

1. The specs for the salvaged EL night light is 120 volts, and .03 watts. Is the fact that the battery I tried to use is only 3.6 volts the reason why it won't light up? Why does the indigo EL light in a Timex Ironman watch light up ok with a 3.6 volt battery in the watch, yet the light I salvaged from the night light does not?

2. What would I need to do to power the salvaged EL light to illuminate with a Lith-ion button cell?

3. Would it be possible to use a 1 inch by half inch size solar cell to power a rechargeable lithium ion button cell that would power an EL light?

4. Are there any good book or web-based sources to learn about this sort of thing?

Thank you very much for any advice anyone can offer.

BB. · January 2007

Re: advice needed for solar powered electro luminscent light

A couple of quick answers:

1. An EL panel is really a capacitor with special phosphors... You need 120 VAC (~60-400 Hz) to make it light. A simple battery will never work.

2. You would need to build/buy/salvage a DC to AC inverter to light the EL (the EL panels are very low power--so the inverter does not have to be large. Also, the intensity is proportional to both the voltage and frequency). EL panels do not last forever and will dim after a few months to years of use. Also, they may be damaged by moisture (typically if the edges are cut and not sealed).

3. Rechargeable cells, like L-Ion can be very dangerous if charged or handled incorrectly (and/or if shorted). You would probably be better of starting with Ni-Cads and/or Metal hydride type cells first. L-Ion--IIRC--need very speciallized chargers and typically have an internal fuse/current limit built into consumer cells.

Just Google Electro Luminescent panels (used quite a bit in laptops and military equipment) and you should find more information than you can ever read.

-Bill

Roderick · January 2007

Re: advice needed for solar powered electro luminscent light

Hi,

Were your hopes to have the EL lit all night by power acquired during the day? Or just to light the EL briefly (like a few seconds, as in reading your Timex)?

Bill is right that Li-Ion requires some care, but I think the danger in charging is only at high charge rates. Take a looks at Rose Electronics, they may have a chip, or even a battery with built-in charger. I don't know if they sell to individuals, though. At the low currents produced by solar cells, you won't even need a temperature monitor for your Li-Ion. However, you need a way to sustain about 4.1 V (depending on battery type) across the battery, and if you have only a single cell, you won't be getting that kind of voltage.

NiMH works better with a pulse charger, but good old NiCd can be trickle charged. Maybe what you want to do is try salvaging a solar yard light. They tend to have about a 2-3" square area of cells on the top, and charge a single NiCd. Also, they use LED, possibly for cost reasons, but it works reasonably. Maybe you can work just on the inverter circuit to provide 120 VAC (at a very tiny current) from a single NiCd, and maybe you can even get an efficiency that allows you to run longer than an LED. Then it would be a simple matter of stealing the solar cells, charger, and battery from the solar yard light.

mike95490 · January 2007

Re: advice needed for solar powered electro luminscent light

The 120V AC night lites, as you found, won't work.

You might try some "EL wire" It's a phosphor laden coax cable, paired with a driver (inverter) that
is even nicer than a square EL panel.
Look for it under names like "cool neon" "glow wire" or even "EL wire".

http://en.wikipedia.org/wiki/El_wire

Brock · January 2007

Re: advice needed for solar powered electro luminscent light

You might want to go with something more simple like a "Krill" lamp. It is powered by AA or AAA batteries and uses that same EL material.

http://www.xenoline.com/krilllamps.html

Honestly though I have a couple and would choose a glo-toob

http://www.thinkgeek.com/gadgets/lights/6536/

over a EL any day. A small LED will get you more lumens per watt or light for the power used. The trick is to find a LED light that is really a power sipper. Something like a PAL survival can run 2 years in "find me" mode and a week in low from a 9v battery.

I would then just use a NiMH battery to power these and charge via a small solar panel. I have one PAL in the kids room powered from 4 AA batteries and I run it a week and then recharge the batteries. I would guess I could go about three weeks before I really needed to recharge them.

http://www.theledlight.com/palights.html

BB. · January 2007

Re: advice needed for solar powered electro luminscent light

I too would only suggest EL type lamps if you have a specific need (like back lighting for instrument panel or an LCD panel--or need EL "cable" for Halloween). They are not the most efficient light and don't have good life.

-Bill

System2 · January 2007

Re: advice needed for solar powered electro luminscent light

Someone mentioned using an inverter to power your Electro Luminescent panels. If you do try this, use only a true sine wave inverter. Since the panel is a capacitor, it will "over-conduct" on modified sine because of all the sharp corners in the voltage and soon burn out the panel. Had one customer who burned out 4 in one week, before switching to another light source.
Wayne

advice needed for solar powered electro luminscent light

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