Plan to mod a...

[Demon-Xanth]

I got a free minifridge from Office Depot thanks to the Hot Deals forum. I opened it up and found the following:
Low quality 80mm fan that occasionally makes noise, very loose bearings.
Peltier (36W?) driven directly from a power supply.
Standard looking flat heatsink held on by two screws.

Here's the plan:
Swap out the peltier with a 72W one I have hanging around.
Put on a larger heatsink.
Put on another fan with better bearings.
Get a more powerful power brick, maybe an adjustable one so I can use it as a temperature control

Possible idea:
Add a thermostat via an RTD, comparator, and relay. And use that as a temperature control.

Edit:
A coworker just gave me a temperature controller kit.

 

[Demon-Xanth]

Parts list:
72W peltier to replace 36W: CHECK
Ball bearing fan to replace sleeve bearing fan: CHECK
Temperature control circuit: CHECK
12V Relay to control temperature: CHECK
Larger heatsink: I can either tear apart an unfinished project, or I think I can grab one from work.
Power supply: Still looking, I can use an AT power supply, but I'd rather use a fanless sealed unit.

 

[BigFatCow]

Post up when you get this done, it would be cool to chill a six pack in like 10 minutes.

 

[Demon-Xanth]

Looks like I gotta use a PC supply. The biggest 12V fanless supply I could dig up was 5.1A, I need 6A for the peltier itself. And yes, I've measured, it pulls 6A@12V.

 

[Demon-Xanth]

Okay, I got a P2 Xeon heatsink that's about the same physical size as the current one, but has many more fins.

The PS plan is to use an AT power supply w/ it's cables removed, a switch installed on the case itself, and a cigarette lighter socket and I can use the cigarette lighter power cord.

 

[Soulkeeper]

a 72w pelt sound kinda modest ( i usually use 2x 120 watters)
but in speaking about this kinda cooling condensation will and should be seen as the greatest foe.
maybe look for some good reviews/similar stuff on google to research a bit.
i also picked up a minifridge with the same kinda ideas in mind
it's just been sitting in my back yard rusting cause i'm too lazy
i was gonna maybe use it to cool the motherboard heatsink, memory, and/or vid card
i just feel that pelts and good waterblocks are the way to go for most
the possibilities are endless when talking about modding tho
should be interesting

good luck

 

[Demon-Xanth]

The current peltier is 36W. And it works. So 72W will be fine, just not with the stock 44W power brick.
Condensation was taken care of by some foam tape around the well that the peltier goes into, this can be reused.

I got all the parts together and will take first pics tonight, and might start modding the PS and building/testing/calibrating the temp controller.

BOM:
Minifridge w/ both AC and car plug: $0
72W peltier: $0
Power supply: $0
P2 Xeon heatsink: $0
80mm ball bearing fan: $0
Temp controller kit w/ sensor: $0
Relay: $0
Cigarette power socket: $7.53

Total cost: $7.53

 

[Demon-Xanth]

PICS!

 

[Soulkeeper]

looks like a fun project, let us know what kinda temps you get

 

[Demon-Xanth]

Well, results aren't encouraging. I think I'm either overdriving the peltier, or it's not designed for large temperature differentials. I went to a much larger heatsink, to the point that the fan moved outside. I'll check on it in the morning. I might be going back to a stock peltier+PS w/ upgraded cooling.

 

[Demon-Xanth]

Checked it before I went to work, got cool. Not as cold as I wanted. I'll measure it when I get home, and if it's not chilly, I got another peltier to swap in.

 

[Demon-Xanth]

END RESULT:
Temp controller couldn't drive the relay. That idea got axed.
72W peltier burned too much power to cool the fridge effectively with the Xeon HS. 44F was the baseline temp, it barely got it cool.
Used the larger heatsink in the pictures, the fan could no longer fit inside. Still only got down to 46F.
Used a 48W peltier, with the big heatsink. It drew enough to use the stock power brick.
End result: 37F.

Not as stellar as I was expecting, but the drinks end up noticably cooler because of the 7F drop.

 

[BW86]

awesome

 

[Demon-Xanth]

Update:
I was loading up some more sodas, and the area around the peltier inside is covered with a thick sheet of ice.

..aww yeah.

 

[canadageek]

wonder what a 200W peltier would do to that thing

 

[rammstein junkie]

umm pop some soda cans

 

[canadageek]

wonder how hard it'd be to make my own slurpee machine with one of those...mount it in my case, redbull slurpee anytime i want!

 

[Demon-Xanth]

The 200W peltier would make it hot. The 72W performed worse than the 36W, the 48W works great though.