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# How long might a Lithium battery (CR1632) power a single LED? Answered

How long might a Lithium battery (CR1632) power a single LED? here is the CR1632 date sheet:www.componentschip.com/details/Panasonic-BSG/CR1632.html

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I had several lighters with so called emergency lights in them.
One had the push button jammed on first use but I did not bother.
Five days later the LED was still emitting light.
So I took it out and did some tests on my own.
No other LED I had was producing good visible light at currents as low as with this LED.
Some more digging on the WWW showed you can get special low current LED's - often used in quality solar garden lights.
Where a standard white LED would need 3.4V and 22mA these special ones only need 2.6V and less than 12mA to glow brightly.
Color is vital too, for example red LED's use much less current than green or white ones.

So if you know how much energy the cell can provide you only need to calculate the demand for the LED to know the run time ;)

There is a circuit consisting of just a just a single LED in series with one or two coin cell batteries.

The short answer is that this contrivance of just a single LED in series with one or two coin cell batteries, this can keep the LED producing some amount of light, for hours, or even a few days, but the intensity of the emitted light decreases significantly as time goes on, so the end of the battery's life is producing light much, much dimmer, than the light produced in the beginning.

It is possible you could design a circuit, for to conserve the battery's energy, make the light dimmer so it can last longer, or only turn it on at night, etc, but if you knew how to design that circuit, you probably wouldn't be here asking the question you're asking.

And besides, there is a certain elegance in simplicity. The design with coin cell batteries does not even require a current limiting resistor,

http://led.linear1.org/1led.wiz

because that resistance is essentially there already, in the internal series resistance of the batteries themselves.

If I had to pick a name for this contrivance, I would probably call it, "LED throwie",

https://en.wikipedia.org/wiki/LED_art#LED_throwies

The blurb I've linked to at Wikipedia there, says a rare earth magnet is a necessary ingredient in the LED throwie. The magnet is included so that when you throw it at steel surfaces, like cars, lamp posts, etc, it will stick there, and put that little light somewhere where people can see it. So the "throw" in "throwie" is there for, "You throw it, at something, and it sticks there."

Because, who puts an energized LED under a basket, amirite?

https://en.wikipedia.org/wiki/Lamp_under_a_bushel

However, I think the essential ingredients of the LED throwie, are simply the LED and the coin cell(s). Moreover the "throw" in "throwie" could also be, "It's so cheap you can throw it away."

As an example of this kind of art, I have seen a version of the LED throwie that arrives in junk mail, and it is this little piece of LED art, that tries to trick the recipient into thinking he or she has won fabulous prizes in some contest, usually being run by local carmongers.

https://www.pcbway.com/project/share/pcbway_Junk_M...

of this device.

I recall one time the local car dealers were mass mailing these LED art objects to people in my town, and from the trash bin at the Post Office, I pulled out like 20 of them, most still glued to the garish, card stock, promotional mail they came with, and gave them to my neighbors' kids to play with.

The kids were impressed with these, and reported that many of these throwies were still glowing dimly, days later.

I have an LED that lights at 1ma and according to to your Panasonic CR1632 has a capacity of 125 mAh at that current.. So the Panasonic CR1632 as of the 2005 data sheet would light the LED slightly over five days... That is over 124 hours... of light..

Of course the voltage of the LED may require more then one battery in series, which has no affect on the time duration owing to the current requirement..

It depends.

what you call powerd up

What sort of LED you use

The current you allow it to draw.

After that you can find out by dividing the mAh rate of the cell by the current. Note by the end it will be VERY dim so when you get your result divide by 2/3 to be sure the LED is well lit.