Thermoelectric USB Charger - Off Grid Electricity.

This strange looking pan is a device to generate power from a low temperature heat source. By using the seebeck effect, it is able to produce enough electricity to charge a cell phone and other USB devices. The best part about this contraption is that it has no moving parts.

The device has a nimh power pack which stores electrical energy for use whenever you need it, the power pack can be detached for use anywhere. The output is 5V through a USB port. This device would work especially well were there is snow available for extra cooling – for example off grid cabins in remote (snowy) locations. It could serve as dual purpose - melting snow for water and producing electricity ? The bigger the temperature difference between the two sides of the peltier the greater the power output.

This idea is not new, it has been around for a long time. See here for some very
old thermoelectric generators

The peltiers produce 0.6W of power to recharge the battery pack.

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Here's what you'll need :

Video  guide to making the pan :

Step 1: Tools and Materials

What you'll need :

Materials

• 2 x TEC-12706 Peltier Modules
• DC-DC USB Step Up converter
• Small switch
• Project box
• Small scrap of vero board
• 4 x 3000mah nimh/ni-cd batteries
• 1N4001 diode.
• Battery holders for the batteries
• Miscellaneous wire, solder etc.
• Thermal compound
• Aluminium or copper milk pan
• PC CPU Heatsink
• 4 M4 x 12 bolts
• 4 Long (>75 mm) M6 bolts for the feet
• Electrical connectors (screw terminal type)
• Silicone tubing.

Tools:

• Drill & drill bits
• Multimeter
• M4 Tap
• Soldering iron
• Files
• Screwdrivers
• Spanners to suit the bolts

Notes: The PC heat-sink must be big enough for the two peltiers to sit on.
I bought the DC-DC converter on ebay, it has an integral USB port.

Step 2: Mark Out Holes in the Pan for the Heat-sink Bolts

The heat-sink will be bolted to the milk pan. Mark 4 holes to for bolts to go through the milk pan into the heat sink. The sizing of these holes will depend entirely on the heat-sink

Step 3: Drill Holes in the Pan to Attach the Heat-sink

Drill out the holes you marked. The drill size should be 4mm

Step 4: Drill and Tap Holes in the Heat-sink for the M4 Bolts

Drill matching holes in the heat-sink with a 3.2mm and cut an M4 thread in these holes.

Step 5: Lay Out the Peltiers

Lay the peltiers onto the heat-sink, ready for the dry fit. It's best to do a dry fit first to make sure that everything lines up properly. When you're ready to assemble the pan for good, apply thermal compound to both sides of the peltiers.

Step 6: Bolt It Together

Bolt the pan to the heat-sink using the M4 bolts. Make sure the peltiers are sandwiched neatly in between.

Take care not to overtighten the bolts as this could crush the peltier chips.

Step 7: Slip Some Silicone Tubing Over the Wires

Slip some silicone tubing over the electrical wires to help protect them from the heat. This also makes the wires a bit neater.

Step 8: Add Legs

Drill four 6mm holes around the edge of the pan for the feet (bolts).

Step 9: Attach the Legs

Bolt the four legs onto the pan.

Step 10: Attach the Screw Terminal Blocks

Bolt the screw terminal to the side of the pan using two M3 x 20mm bolts.

Step 11: Connect It All Up and Test

Connect the two peltier chips in series using the screw terminals. Light some candles underneath the thermoelectric pan and fill the pan with water.

Connect a multimeter to the output and measure the voltage. If the voltage is very low, such as 0.1 – 0.5 volts, then one of the peltiers is probably connected the wrong way around. Flip the wires around on one of the peltiers.

It will take around 5 minutes for the heat-sink to reach full temperature, at this point you should see between 3 – 7 Volts DC output.

Step 12: Build the Step Up Circuit

Solder up the circuit for the step up converter. The peltiers are connected to the battery pack through the 1N4001 diode. The step up converter is connected to the battery pack through the switch.

Note: The 3.5mm jack shown was not used in the final build.

Step 13: Fit It All Into the Project Box

Cut out the holes in the project box for the switches and USB port. The USB board is glued to the scrap of strip-board to keep it securely in place and the strip-board fits into the slots in the project box.

Comments

[Cambenora]

Excellent instructable. It's good to see Peltier cells being used in this way.

[scraptopower]

Thanks.

[masterleo]

could you please tell us how many Amps (and watts ) it produces ? ?

please add it in the instructables

[marcellinelee71]

p=v*a so there's no need for him to state wattage, he says it has a variavle of 3-7v, and there's a multimeter reading i didn't look at. the amperage is something i'd like to know though..

[masterleo]

Thanks for your reply, for things to be clear, I would like Wattage and volts and amps. Just to be sure the guy is not a Chinese layer and knows how to make the calcs. Thanks.

[keegancdr]

is this the step up dc-dc converter you used?

http://www.ebay.com/itm/USB-DC-DC-Converter-3V-to-5V-1A-Adjustable-Step-up-Boost-Power-Supply-Module-/150897682187?pt=LH_DefaultDomain_0&hash=item232233e70b#ht_4631wt_1417

[scraptopower]

Yep, that's the one.

[keegancdr]

Thanks a lot! Another question if I were camping could I leave this contraption running all night? Or untill the candles went out? Or is there a time limit to how long I can run it? I'm wondering for like leaving my phone plugged in and charging over night ( in a fire safe environment )

[marcellinelee71]

there's a design flaw, the bolts should be on the sides, not corners, which makes for a shorter peltier life span; other than that? you're good to leave it running for a decent ammt of time; just check temps of the heatsink to make sure things don't get too hot

[Lemon]

If you were worried about the candles being left overnight, you could try boiling up some water and replacing the candle with this heated water. Cooling 3 pints of water from 100 degrees to 15 degrees involves roughly the same amount of energy transfer as burning one of those candles would, so if you had a big enough campfire to boil a large amount of water during the day it could be something to consider.

[haniffwahab]

hai,
i want to ask, i have try the project, but my thermogenerator have produce only 0.5v , could u give some advice how to make thermogenerator produce 3v and how about temperature and temperature ambiance?

[marcellinelee71]

instructables says if you only receive .5v you probably have one of the peltiers backwards; just flip the wires and try again

[HarshB]

This is a excellent instructable! I was wondering however, do we need to use 2 heatsinks; one in the bottom of the pot, and one in the inside? Or just one in the bottom. Appreciate the help.

[marcellinelee71]

there's only one; it's outside, on the bottom of the pot

[Niveeee]

what will happen if we use a larger heat sink? and not a a compact one

[marcellinelee71]

probably same thing but potentially lower electrical output. if the peltier cells can't get heat, they can't put out power

[mnaderi11]

Thank you @scraptopower ;)
It was much helpful to get making.

[blamo89]

Check out the biolite camp stove its similar but you can also cook on it

[haniffwahab]

hai,
i want to ask, i have try the project, but my thermogenerator have produce only 0.5v , could u give some advice how to make thermogenerator produce 3v and how about temperature and temperature ambiance?

[mlove8]

hi