76Views3Replies

# LED run time computation? Answered

If a cell of 10 volts were to operate on a joule thief circuit on 2 1-watt LEDs. How long will that last?

Tags:

The forums are retiring in 2021 and are now closed for new topics and comments.

I probably could design a magnetic oscillator so that it saturates before it burns the transistor and LED get fried but then like Rick points out the battery capacity and the changing efficiency of the joule thief will not really help you calculate a definite answer.

I save my dead batteries and put them into a JT that does 8 or 9 days lighting a white, blue and red 24/8 with the last days only red is visible.

I have had some red throwies that ran two weeks !

A banana.

A lot depends on other things.

1. How efficient the joule thief is.

2. how you control the current to the LEDS

3. A joule thief isn't intended to drive 2 watts of LEDs It provided milliamps of electricity.

4 If you slap 10 volts across the LEDs without any current limiting circuitry then they will last fempto seconds, maybe a few milli seconds.

5. The details of the LEDs matter a lot.

What is the forward voltage of the LEDS and what is their optimum current rating.

I should have added the capacity of the battery is needed as well.