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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?

Thanks

Matt

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## 6 Replies

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.

b1g5l1ck (author)2011-04-07

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

lemonie (author)2011-04-08

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

L

steveastrouk (author)2011-04-09

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.

lemonie (author)2011-04-09

That's pretty much what I thought.

L