A new way to power your peltier??? read on

[mark]

Hey guys, haven't posted much, been to busy.

I have gotten myself a new AMD 3000+ with MB, I am thinking of peltier cooling it.
I am not new to peltier cooling as I am on a Slot 1 Intel Pentium 3 700e that is overclocked to 1120MHz with an 86W peltier with Alpha P3125 Heatsink.
I was playing around with my multimeter at work and was checking voltages of Laptop power adapter. Here is what I was on... Sony power adapter; output shows 19.5V DC and like 5.6 Amps. Now with the multimeter I got 19.9V DC and nearly 10 Amps If I remember corectly.

I do use a Sony power adapter (from Sony Discman) that is rated at 4.5V DC and 0.5 Amps to run 2 80mm Case fans that are mounted inside my monitor.

Has anyone tried to run a pelt with one of these adapter?

Do you think it will work?

I will probably test it with my 86W peltier, without the CPU, but still with the Heatsink to see if it blows up or anything.

Any info, comments, question?


mark

 

[LuckyBob]

Sounded like a great idea, until I did some math on it.
First off, check the rated power output on the supply; it's the most accurate safe value the thing's able to put out. I wouldn't rely on a multimeter's readings to determine safe output levels.

Anywho...
Given your upper ratings, 19.9vdc*10a = 199w. Make sure you've got a >19v TEC in the first place; if so...
Given that you were using a 120w 24.6v TEC (that was the closest I could find in a pinch that was >19v)
Imax=7.9a
Vmax=24.6v
Qmax=120w

At a glance it looks like it'll work fine. A 120w peltier on a 200w power supply is plenty of headroom. But if you do the math on the TEC, you'll notice that the actual power consumed is quite a bit higher than the heat dissipated.
24.6*7.9=194w <- that's cutting it kind of close IMO.

Granted, since the PS is capable of only 19.9v, it might just work...
19.9*7.9=157w. Sounds like that particular TEC would work. The only things that'd concern me are:
a) 120w isn't exactly enough to cool a new 3000+. I'd figgure more like 226w or so, which suck well over 300w of power.
b) I doubt that laptop power supplies are designed for consistantly high power draw - for the most part they're charging the battery and giving short bursts of power to start things spinning and whatnot. Overheating might be an issue.

Anywho, there's my two cents. Good luck.

 

[Veland]

Oh, and measuring voltages with a DMM is just fine, but measuring amps is a little different. Even though you got a reading without blowing the DMM, the 10amps output is NOT for continious use. That will destroy the power adapter.. Go for the rated values..

And many power adapters for laptops get quite hot from just charging at way below their rated max power, so will probably get burning hot if 100% power all the time.

But if you got one to spare, give it a try! Just make sure you don't leave it unattended until you're sure it won't catch fire!

 

[Crazy Jayhawk]

I would suggest using power adapters with the same voltage in parallel. That way the load from the TEC would be spread out over multiple adapters and you would have less risk of them burning out.

 

[Surreal]

Good ideal if you are trying to burn your house down for an insurance check! lol

But seriously you would be much better off geting two generic ATX PSU with 12-15A ratings on the 12v rail. If your lucky you could go to a computer shop and they might give you some AT PSUs. Gut them out, make a custom houseing, and thenyou have a nice TEC power supply.

This is a pic of two generic ATX PSU with a 14a rating. THey are powering a 226w tec. As you can see the temp is 10F. I still run those PSUs. Cost me about 15each after shipping. The place I purchased them from made about $12 in shipping. What a rip.

 

[L337 M33P]

Lol that current is in no way sustainable from an adapter that is only meant to supply 1/2 that current. Also the voltage was measured when there was no current flowing, I bet you that when you load it to 10A you will get something like half the voltage you read there. If you did make it power a peltier I think it would last 20 seconds before burning itself through the ground.

This sort of adapter is a linear voltage regulated one, i.e. it uses a standard transformer, rectifier and little regulaty thing. TEC PSUs are most often SMPS, switch mode power supplies, which are about 2x as efficient at power conversion, more so at high loads.

 

[Wolfe]

Hey! I've got the same multimeter!
Hmmm. I always thought that laptop Power supplies were switching.

 

[Black_Ops]

laptop supplies are switching, thats the only way they can be so small, but thier components were never designed to output that much current. most designers rate stuff at 5-10% lower than they can safely supply.

i would vote that it would hit a thermal protection mode and turn off before it blew up but i still wouldent try it.

 

[CrashOveride]

Good ideal if you are trying to burn your house down for an insurance check! lol

But seriously you would be much better off geting two generic ATX PSU with 12-15A ratings on the 12v rail. If your lucky you could go to a computer shop and they might give you some AT PSUs. Gut them out, make a custom houseing, and thenyou have a nice TEC power supply.

This is a pic of two generic ATX PSU with a 14a rating. THey are powering a 226w tec. As you can see the temp is 10F. I still run those PSUs. Cost me about 15each after shipping. The place I purchased them from made about $12 in shipping. What a rip.

Did you just combine the 2 12v rails and hook it up to the peltier to give 28a? or does it not work like that.

 

[L337 M33P]

heh that's incredibly dangerous to run PSUs of a switch-mode design without a cover - they have up to 300V on the mains side

Please tell me they are going to be installed in a proper case

 

[CrashOveride]

heh that's incredibly dangerous to run PSUs of a switch-mode design without a cover - they have up to 300V on the mains side

Please tell me they are going to be installed in a proper case

Its only dangerous if you touch them or have things in your house that don't know better (pets, small childern, flies).

I have my PSU in my case w/o a cover, or even a metal bottom, its basicly like those but with a plasic bottom on it, right over the CD-Drives, as long as you know the danger and act accordingly its not that bad.

 

[vonkaar]

nope! Ignore L337 M33P! Blankets make FINE cases for TEC cooling =p

 

[star882]

"heh that's incredibly dangerous to run PSUs of a switch-mode design without a cover - they have up to 300V on the mains side"
It's more like 700v P-P @ a high frequency since the flyback voltages can get very high.
I have ran several switching PSUs without a cover(and my friend Christina Mahoney has run many dozen switching PSUs without a cover(she designs, modifies, and repairs switching PSUs)).
"Did you just combine the 2 12v rails and hook it up to the peltier to give 28a? or does it not work like that."
By looking closely, it looks like that's how he did it.

 

[star882]

"And many power adapters for laptops get quite hot from just charging at way below their rated max power, so will probably get burning hot if 100% power all the time."
Maybe it's time to mod the PSU with some Delta fans.