Joule Thief

Discussion in 'Off Grid Living' started by kckndrgn, Sep 16, 2010.

  1. kckndrgn

    kckndrgn Monkey+++ Moderator Emeritus Founding Member

    I made my first joule thief, if you don't know what one is google is your friend but basically its a small circuit that bumps the voltage of a dead battery.

    As you can see in the attached image, I'm powering a 5v blue LED light with a single "dead" (less than 1V) AAA battery. This battery ran for 4 hrs, before I removed it so I could go home, not because it had died.

    I've also powered the LED using a small button battery, and a "dead" AA battery. I put the "dead" in quotes because the batteries were removed from devices that stopped working due to the batteries being drained.

    There are many applications for a joule thief. Make a small flashlight that will run on most 1.5v batteries until the batteries have less than .5v left in them (I did have a battery that was .4v, and while it did "light" the LED it was not a useful light). A JT can take .5v from a solar cell and charge another battery. This is a project I plan on making.

    Yeah, I know the solder joints lack finesse but, it took a couple of tries to get everything worked out right. I did have to buy all the parts for it, with the exception of the battery holder it was less than $4.00 in parts. Now to clean it up and make put it in a container and I'll have a flashlight that will run on "dead" batteries :)
  2. bnmb

    bnmb On Hiatus Banned

    What? Only one LED? I power 10 paralel and 10 serial LEDs from 2 secondaries of the toroid, and one 1.5V battery lasts about 90 days...try replacing resistor with 50K pot and fine tune on multimeter until battery voltage starts rising...
  3. ghrit

    ghrit Bad company Administrator Founding Member

    Make a Joule thief. (No copyright notice posted --)

    I've often thought that one might put a lot of "depleted" batteries in series until you have enough voltage to run something. In this day and age, there are a lot of used (but not flat) cells lying about. Given the behavior of dry cells (and wet ones for that matter) it could be a problem to find which of them in the series really sucks the performance out of the system, but at least something might be recovered from the low voltages remaining.

    I have a used up and changed out m/c battery that was waiting on a trip to the recycle center. Now, I think it's waiting for a project.
  4. bnmb

    bnmb On Hiatus Banned could first shock your "depleted" batteries from a car battery...5 second shock and then check voltage and put in JT...won't be needing a new batteries for years...There's a way all batteries can be made to last 10 times more, but it's not used deliberately by battery companies...
  5. Mountainman

    Mountainman Großes Mitglied Site Supporter+++

    Was wondering if you meant to say That's a way all batteries can be made to last 10 times more, before I try it and the battery blows up in my face. Or is there some other way to make them last 10 times longer?
  6. bnmb

    bnmb On Hiatus Banned

    By shocking the ordinary batteries from a car battery, you can run them with JT dozens of times, before they are completely ruined. But...there's another way, where if batteries were made that way, they would normally last at least 10 times more without shocking or anything else...
  7. Mountainman

    Mountainman Großes Mitglied Site Supporter+++

    Thank you for the clarification.
  8. kckndrgn

    kckndrgn Monkey+++ Moderator Emeritus Founding Member

    OK, so you know this magical way to make batteries last 10x longer, with the craze of the electric car going on now, and the "green" movement you should start a company that manufactures these batteries.
    If you can come in at a comparable price on the user cost of the battery, and you batteries last 10x longer, you'll become the number one battery manufacturer in the world in no time!

    Oh, yeah, I would like to see some pics of your 10 parallel & 10 serial JT that run for 90days. Is it 10 parallel running for 90days or 10 serial, or 10 parallel with 10 serial or 10 parallel of 10 serial (making 100 LEDs)?
  9. bnmb

    bnmb On Hiatus Banned

    It's not new or magical way...just the opposite! It's scientific, old way! Just check the beginning of 20th trucks were running on batteries then...just check how they were made and what and how they used as oxydizers! That is the key!
    In the JT I connected 10 parallely soldered LEDs on first toroid secondary, and 10 serially soldered LEDs on second toroid secondary. I have nothing connected on the toroid primary.
    I made this configuration to maximize both voltage and amperage draw, since normally 1.5V battery can never power even a single LED that works on 3V and draws 25mA, but with the modified JT it looks like it gives at least 30V and 250mA...
    As for the pictures, I guess I might do that as soon as I rebuild the circuit, in couple of days maybe...And then what? You'll stop being sarcastic?... :D
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