Browsed by
Month: October 2010

Joule Thief Copper Zinc Battery Low Voltage Energy Harvesting Experiment

Joule Thief Copper Zinc Battery Low Voltage Energy Harvesting Experiment

Comments 0 Comment

I was thinking what else could I use this Joule Thief kit for? It dawned on me that I could harvest energy from a homemade battery. So this morning I set out to make a zinc copper vinegar battery. I took a piece of copper pipe and a zinc coated bolt from my junk pile. Cleaned the copper pipe with a sanding sponge. Placed the two pieces in a plastic container, poured in some vinegar, connected to the JT_kit001b and wow it worked!! There was light coming from the LED!!! I measured the voltage coming from the homemade battery at ~550mV and the battery current was somewhere around 15mA.

Next I thought, well I could remove the LED and put a rectifier diode on the output of the Joule Thief board to see what kind of voltage I was getting. I put a 220uF capacitor on the rectified output and it charged up to >10VDC in a few seconds.

Well onto the next experiment, trying to recharge a depleted AA NiMh battery with the Joule Thief harvesting energy from the zinc copper battery. Will update with results at a later date as I think this may take a couple of days.  Here is the Joule Thief schematic showing what I was doing.

Joule Thief Circuit Battery Charger

Update: 6:40AM Oct 31st : Last night I started with completely depleted NiMh (520mV with 10mA load) After charging overnight the static value is sitting at 1.210V. The Zn Cu battery is not fairing so well the output voltage is sitting at 425mV and the output current is now at a paltry 2.9mA (the JT circuit is still running, LED is still lit) The bucket of vinegar is looking really ugly. I think I may have to find a more robust source of Zn or another material to make the ‘battery’ out of.

Update: 9:20AM Oct 31st after running the JT charger circuit on the Zn Cu battery for about 12 hours the input voltage dropped too low (about 390mV) to keep the circuit running. The NiMH static voltage is at 1.225V. Time to try a different input battery.

Another experiment will be trying to harvest the low voltage output from a thermal electric cooler (TEC,  Peltier device or Peltier cooler) when heating one side and cooling the other.

Joule Thief Copper Zinc Battery Low Voltage Energy Harvesting Experiment

Joule Thief Copper Zinc Battery Low Voltage Energy Harvesting Experiment

Comments 0 Comment

I was thinking what else could I use this Joule Thief kit for? It dawned on me that I could harvest energy from a homemade battery. So this morning I set out to make a zinc copper vinegar battery. I took a piece of copper pipe and a zinc coated bolt from my junk pile. Cleaned the copper pipe with a sanding sponge. Placed the two pieces in a plastic container, poured in some vinegar, connected to the JT_kit001b and wow it worked!! There was light coming from the LED!!! I measured the voltage coming from the homemade battery at ~550mV and the battery current was somewhere around 15mA.

Next I thought, well I could remove the LED and put a rectifier diode on the output of the Joule Thief board to see what kind of voltage I was getting. I put a 220uF capacitor on the rectified output and it charged up to >10VDC in a few seconds.

Well onto the next experiment, trying to recharge a depleted AA NiMh battery with the Joule Thief harvesting energy from the zinc copper battery. Will update with results at a later date as I think this may take a couple of days.  Here is the Joule Thief schematic showing what I was doing.

Joule Thief Circuit Battery Charger

Update: 6:40AM Oct 31st : Last night I started with completely depleted NiMh (520mV with 10mA load) After charging overnight the static value is sitting at 1.210V. The Zn Cu battery is not fairing so well the output voltage is sitting at 425mV and the output current is now at a paltry 2.9mA (the JT circuit is still running, LED is still lit) The bucket of vinegar is looking really ugly. I think I may have to find a more robust source of Zn or another material to make the ‘battery’ out of.

Update: 9:20AM Oct 31st after running the JT charger circuit on the Zn Cu battery for about 12 hours the input voltage dropped too low (about 390mV) to keep the circuit running. The NiMH static voltage is at 1.225V. Time to try a different input battery.

Another experiment will be trying to harvest the low voltage output from a thermal electric cooler (TEC,  Peltier device or Peltier cooler) when heating one side and cooling the other.

Joule Thief PCB

Joule Thief PCB

Comments 0 Comment

The Joule Thief kit PCBs finally arrived. I felt like a kid at Christmas opening the packages to see the actual PCB.

Joule Thief Progress

Joule Thief Progress

Comments 0 Comment

Today I experimented with the components for the surface mount version of the Joule Thief.  The experiment involved trying a different combination of  transistors and resistors. Finally I have settled on the values for the production version of the surface mount JT PCB. When this board is completed it will be one of the smallest JT circuits available and should measure around 0.276″ x 0.276″ x 0.118″ (7mm x 7mm x 3mm)

The final prototype was capable of running from input voltages of 600mV to 2.1V , it could drive two series white LEDs with a voltage as low as 600mV and they were still giving off a decent amount of light. At 600mV input the current draw was 6mA, at 1.5V in the current draw was  about 70mA, and at 2.1V the current draw was a little over 100mA.

The amazing thing was without the LEDs connected I was seeing peak voltages >100V with the 2.1V input voltage. Running this circuit without a load is not recommend because it was exceeding the absolute max voltage rating of the collector to emitter of the transistor.

I was using OSRAM Hyper PointLEDs that are rated for about 800mcd, and they are tiny at 1.9mmx3.5mm. See the LW P4SG Datasheet, these LEDs and many other LEDs will be available for purchase in the products section when the commerce section of the MSH website goes live later this year.

The next step of this project will be to experiment on the printed circuit board. I still have to order parts for the surface mount version so I expect to do some more lab work on this in a couple of weeks.

I spent time laying out the thru-hole Joule Thief PCB today. This board is designed so that you can experiment with different component values so I made the board as rugged as possible so that the parts can be removed and replaced many times without worrying about damaging the PCB (so long as good soldering practices are followed). This board measures 0.775″ x 0.795″ (19.7mm x 20.2mm).  This kit will be offered with complete parts or as individual components. The introductory price for the individual PCB will be $2.99 or as a complete kit with a toroid core, 80 inches of magnet wire (40inches red, 40 inches green), a transistor, an ultra bright white LED and resistor for about $5.99