Solar Heated/cooled Lunch Box

by simonvp

20K7712

Intro: Solar Heated/cooled Lunch Box

Summer or winter, some lunches taste better when they're cool and fresh, other when they're hot.
To be able to heat/cool your lunch wherever you are, I made a solar heated/cooled lunch box.
The solar panels charge the batteries, hidden below it.
Half an hour before lunch starts, you press the switch, either to heat or to cool.
The power of the batteries heats up or cools down the Peltier element at the bottom of the lunch box.

Components:

-Solar panel and batteries (taken from a IKEA SUNNAN lamp)
-Peltier element (taken from a camping cooler)
-Lunch box
-Switch with 3 positions (has to be able to switch polarity)
-2 metal plates (cut out of a biscuit box)
-2 polystyrene sheets (material of a CD jewel case)
-Soldering iron
-Glue

STEP 1: Placing the Solar Panels

Draw the contour of the solar panels on the upper side of the lunch box.
Remove the inside of the contour with a cutter.
Place the solar panels.
Fix the panels to the top with glue (I prefer a glue gun).

STEP 2: Placing the Switch

Draw the contour of the switch on the upper side of the lunch box.
Remove the inside of the contour with a cutter.
Place the switch.

STEP 3: Placing the Peltier Element

Draw the contour of the Peltier element on the bottom of the lunch box.
Remove the inside of the contour with a cutter.
Glue the first metal plate on the bottom.
Glue the Peltier element inside the removed contour onto the first metal plate.
Cut out a sheet of insulation and place it around the Peltier element.
On top of the Peltier element, place the second metal plate. (These plates conduct the heat and spread it)
When everything is in place, make sure the wiring is correct and the Peltier element works (both heating and cooling).

STEP 4: Placing the Polystyrene Sheets

Glue a sheet of polystyrene (or any other plastic that is safe to be in contact with food) on top of the second metal plate and seal up the sides by melting it with an old soldering iron.
Repeat the previous step for the top of the lunch box.

STEP 5: Done!

Enjoy eating your lunch, whether it's hot or cold!

10 Comments

limayelaksh 1 year ago

Hello sir/madam, I am unable to take the proper measurement, can you please share a diagram and measurements of the components?

acuchetto 10 years ago

I can't tell how the heating element is prevented from melting the plastic and/or insulation.

simonvp 10 years ago

Hi! The Peltier element heats up to about 70° celsius. Polystyrene has a glass transition temperature of 95° celsius so no melting problems here!

Soose 1 year ago

This project is exactly what I need. Pity this was 8 yrs ago. Ikea of course no longer has a solar light. And hope you're still around. Any thoughts on this project if you were to start over today?

I have an injection med for absolutely critical for emergencies. It has to be kept cool. I use the blue ice packs but if I forget and leave the insulated lunch bag in the car overnight or on a hot afternoon when I get home, I have to toss the med. I was looking and can't find anything like this commercially available.

My better half is good on electronics. I already have a Peltier element from years ago, but it's big and the heat sync is very bulky and heavy - maybe can't be helped. I'll have to find it , not sure of the power requirements but it was not likely a small one. I also do not have any smaller solar panels other than for solar walkway lights using 2 AA batteries (I think) - will have to look.

Please, what are your thoughts for today, if you were to start from scratch? (Hope this sends notifications.)

Navytachi 9 years ago

How will I know if it is heating or cooling the food ? Like, how will I adjust it so it can cool or heat ?

mscookieninja 9 years ago

So how much did this cost to make? And could I just buy a eBay solar panel instead of the Sunnan solar panel? But I guess I would have to buy the rechargeable batteries then too if I got it off eBay. How did you hook up the wires? Like which wires go where? lol. Could you do this on a bigger cooler? Would you have to have a bigger solar panel than? Sorry for all the questions but I really have no clue when it comes to wires and making things haah. I just wanted to make this for my bf who does road construction and needs cold drinks on really hot days without the use of electricity. Plus I don't have a soldering iron... do I really need one? What could I do instead? Thanks!(:

simonvp 9 years ago

It didn't cost me anything, as I took all the components of scrap parts and used a regular lunchbox I had lying around. You can just buy a solar panel on eBay, just make sure it isn't too big and can charge your batteries. The problem with buying a regular solar panel is that you still need the components that charge your batteries (in the Sunnan solar panel they're already built in..) It's hard to explain wiring via text. Best thing is to ask it to someone you know, who knows something of electronics.. A soldering iron is strongly recommended. You kan also try to wrap the wires around each other and the components if that works out!

simonvp 9 years ago

It didn't cost me anything, as I took all the components of scrap parts and used a regular lunchbox I had lying around. You can just buy a solar panel on eBay, just make sure it isn't too big and can charge your batteries. The problem with buying a regular solar panel is that you still need the components that charge your batteries (in the Sunnan solar panel they're already built in..) It's hard to explain wiring via text. Best thing is to ask it to someone you know, who knows something of electronics.. A soldering iron is strongly recommended. You kan also try to wrap the wires around each other and the components if that works out!