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Basic LED project Answered

Hi there

I have an idea in mind and would like to know if you guys think it would be possible to make.

The object is for the battery to last a minimum of 150 hours of constant use.

I want to use the smallest possible LED say 2mm or even a SMD will be sufficient, the led must run off a very small battery either a LR44 / CR1225 or something similar in size and the design must have an on off switch.  

Do you have any suggestions? Is this even possible?

Any ides?





Determine and calculate the power requirements of your LED at the specified luminosity and then see if the battery can supply that amount of power.

Hi There

Ok the Led that I was thinking of using is the following:

3mm, Round , T-1 , 1.6V Forward, Current Test 1mA. ( minimum luminous intensity specified 1mA )

Peak forward current 300mA , Average forward current 20mA , DC Current 30mA , Reverse Voltage 5V

Would this led work on a either of the following batteries? How would I calculate how long each battery would last if the led was turned on and left on until the battery dies?

Battery 1 : 3V , Standard Discharge current mA1, Nominal capacity mAh 50
Battery 2 : 3V, Standard Discharge current mA2, Nominal capacity mAh 120
Battery 3 : 3V, CR1632 Capacity mAh 140, Standard Discharge 0.1mA
Battery 4 : 3V, CR2032 Capacity mAh 225, Standard Dischare 0.2mA
Battery 5: 1.5V LR44 Capacity mAh 170

Battery 2 would in theory give you 120h @ 1mA.
3 and 4 would be way over their standard discharge rate
Battery 5 would in theory give you 170h @ 1mA, if it'll sustain 1mA


Standard Discharge rate is a measurement point, not a limit. That said, generally SDR is the maker's best discharge rate, where you get maximum capacity - 10x the rate may get 10X less stored energy out.

You apparently know more than I. There should be a simple power formula to give you something in usage rate 1ma/hr? Then you would need to find out maybe how much juice is stored in a fresh battery. If you have the parts, hook it up and wait a week to see what happens. Good luck.