PeltierFridgeWorking

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.

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.

The exterior received the same treatment, but with two layers, as I had some remaining space.

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.

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.