PeltierFridgeWorking

Written 2016-01-24

Tags:Peltier Woodsman Fridge 

Rationale

By converting from a standup to a chest configuration, I hoped to stop losing so much cold air every time the door opened. Since I needed to pull the cooling units to replace them anyways, it seemed easy enough to do it all in one go. And, since I want to run the fridge direct from 12 volts, I tossed the broken control board.
Peltier chest fridge

Heatsink Positioning

In the current iteration, the heatsinks are mounted to the door. While I belive this the most efficient location, the usability is not ideal, as there are fans spinning on what could instead be a usable surface. If I do this again, they will move to the top of the back wall.

Additional Insulation

I added an inch of foam insulation to the back-now-bottom of the inside of the fridge and filled the space behind it with insulating foam. Finally, some silicone seals it in.
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The exterior received the same treatment, but with two layers, as I had some remaining space.
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Door Gasket Installation

Originally I wanted to move the door gasket from the door side to the bucket side, but after doing so, there were clearance problems with the hinges, so I had to move it back.
2016-01-24_05-21-40

Performance

Over a few hours, the fridge reached 37 Fahrenheit(2.8 Celsius), and seemed to be holding well. Opening and closing the door did not trigger a large loss of cooling, which is what I was going for.

Future thoughts

  • Usability-wise, the heatsinks should be on the top of the rear wall instead of on the door
  • Peltiers tend to be less efficient than compression coolers for the sorts of temperatures I want to hit. It may be better to buy a compression mini-fridge and convert to a 12-volt compressor.
  • Running about 9 amps from my motorola power supply makes it very hot, but does not quite blow the mains fuse
  • An extra layer of insulation around the outside might help as well
  • Might want to move to 4 peltiers in a 2x2 configuration. Peltiers in series can reach lower temperatures, but in parallel can cool faster. Current configuration is 2x parallel.