Trying to design new LED light? Will button cell lithium batteries work?

Newbie here trying to design compact LED light. As the design is not the typical cylindrical flashlight type assembly, I would prefer to use the button cell lithium batteries. The bulkiness of the AAA batteries does not allow for the flat design. Can anyone provide information or give their experience on this type of battery and how it would match up to the AAA. I will be using several of the button batteries for the project.



Thanks in advance! ~Newbie06

Hi newlight-06 and welcome to CPF-

It depends on the current requirement of your project. Lithium coin cells are very commonly used in small keychain LED lights.

For a basic comparison a typical AAA alkaline battery is rated at about 1250 mAh at 1.5V. A commonly used CR2032 lithium cell is about 225 mAh at 3V.

You will generally not see coin cells used in a high current or multi LED light. They just can't deliver the required current. If your project involves 1 or 2 5mm LEDs you could power them with these cells.

Mark

If I could make it work on three LED's, do you know how the run time on these type of batteries would compare with the standard AAA?

I've never had any multi LED coin cell lights, but I have one light that runs 3 LEDs on 3 LR44 button cells and a similar one that runs 5 LEDs on 3 LR44 cells. They are kinda crappy lights and I've not used them enough to know about runtime.

The larger button cell LR44s are 1.5V and have 150 mAh vs the 225 mAh of the 2032. I would expect that if they you were to wire three LEDs in parallel and each was run at 20ma, that you'd get about an hour per 2032 cell assuming perfect regulation or about 20 minutes per LR44 cell. But those are only very slightly educated guesses.

Also, remember that mAh rating and operational voltage goes hand in hand... so you can look purely at the mAh rating, you need to consider what voltage you'll be sending to the LED.

Edit - Running a single 5mm LED run an AAA cell, we expect between 3.5 and 7 hours of rutime using the ARC (7 hours) and the CMG Sonic and Dorcy AAA (3.5 hours) as examples.

Direct drive from a pair of 2016's or 2032's will run the led for a very long time if you don't mind it getting dimmer and dimmer. Try a Princeton Tec Scout (2-led headlamp powered by four 2032's) for the kind of thing it sounds like you might have in mind. Also of course the familiar coin cell squeeze lights (usually two 2016's and one led).