Peltier device kinda sucks

I bought one of those mini fridges from Craigslist and took the Peltier and heatsinks out of it. Installed it in a medium size insulated grow box (36"wideX24"deepX48"tall) with the cold heatsink and fan inaside the box and the hot side heatsink, fan and power supply outside the box. I kicked it on during lights off to test it out and it lowered the temp from 77 to 71 in about 6 hours.

That seems pretty useless it must be too small for a room that size. The whole system draws 68 watts total. Each fan takes 2 watts so I assume the peltier itself is a 46 watter and it is running at 12v so maybe drawing a bit less, the rest is waste in the power supply.

So maybe it would be helpful in a micro grow or if I got a beefier one it could affect a medium size box during lights on. The peltiers are cheap as dirt and easy to get, the problem is finding heatsinks and AC-DC power supply that is big enough and efficienct (PC power supply is probably where its at).

SupraSPL said:

I bought one of those mini fridges from Craigslist and took the Peltier and heatsinks out of it. Installed it in a medium size insulated grow box (36"wideX24"deepX48"tall) with the cold heatsink and fan inaside the box and the hot side heatsink, fan and power supply outside the box. I kicked it on during lights off to test it out and it lowered the temp from 77 to 71 in about 6 hours.

That seems pretty useless it must be too small for a room that size. The whole system draws 68 watts total. Each fan takes 2 watts so I assume the peltier itself is a 46 watter and it is running at 12v so maybe drawing a bit less, the rest is waste in the power supply.

So maybe it would be helpful in a micro grow or if I got a beefier one it could affect a medium size box during lights on. The peltiers are cheap as dirt and easy to get, the problem is finding heatsinks and AC-DC power supply that is big enough and efficienct (PC power supply is probably where its at).

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you're not going to do much using a 46w pelt. secondly, if you are using an air cooled heatsink to cool the hot side of the pelt, then you can almost guartantee that it's not going to be doing much. even in a home computer a pelt is going to be around 125w and being cooled by a dedicated high end liquid cooling loop.

the kit that you find in those cheap mini fridges, and most fridges unless you're looking commercial walk-in etc, is designed for nothing more than to keep food/drink at a constant temperature, an easy task, they are not designed to be constantly trying to keep a temperature down, and as such it's almmost guaranteed to fail after a relatively small period of time. so as such you would not want it to be an important part of your grow.

and with regard to the general natire of your title, in the right hands, under the right conditions, under the correct application, pelts and TEC's can be frigging insane. take your delta T, figure out what you are requiring and you should be able to cool it as is required

You're right I should have said mini fridge pelt sucks. I was only looking for a few degrees of temp drop just to take the edge off on the hottest summer days. I also bought a compressor style mini fridge but I doubt I will be able to take it apart and put it in the bat cave. It only draws 100 watts and it kicks the crap out of the 68 watt peltier setup. The pelt fridge struggled for hours to bring the temp of an empty fridge from 75 to 45 (although it did eventually and cooled my beer perfectly!)but the compressor fridge reached 37 degrees in minutes and has a freezer section. So considering that, I can see that the efficiency on this particular peltier setup is relatively poor. Maybe efficiency can be increased if it was powered by DC power and water cooling for the hot side like you suggested.