Inexpensive high current peltier power suppply

[71skylark]

I was thinking instead of spending $300+ dollars on a high current 24v supply for my peltiers, I could go old-school and build a motor generator with a 2 or 3HP electric motor and a 24v alternator. Anyone have any thoughts about wether or not this would work?

[Diggrr]

Yes, it probably would. There are two things to keep in mind while engineering it though.
The alternarnator requires current from a battery to energize its windings. It uses electromagnets to produce current flow so a constant feed from a battery of the same voltage is required to be maintained along with the system. This can be charged from the alternator as it is run, just like in your car.

Large electric motors, and especially alternators produce very large electromagnetic interference, so this setup would have to be shielded (ie. grounded metal cabinet), or kept many feet away from the computer. The EMF will interfere with the computer's operation.

Try a www.google.com search of the term homebuilt generators.

You sure could power a heap of peltiers with an alternator. I've seen them as big as 24v 240amp.

[Christoph]

If that's too much work, you could just get a cheap AT PS off ebay.

[Voodoo Rufus]

You can also get some cheap high-power bench power supplies that you might be able to fit in the case that could get up to to 400W I bet. Ebay's great for finding cheap electronics.

[71skylark]

that is where I got my last 24v 1200w power supply which promptly quit after about 10 hours of use. The wait on ebay begins again.

[FrozenInHI]

damn, 24v, eh? you might see if you can get a lower voltage peltier, they make them up to 223w for 12 to 18v, cuz then you can go with a Radio Shack ordered PSU that supplies 13.8v at 20/25a. it's only 119bucks too, go here to see all the supplies they have:

http://www.radioshack.com/category.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F008%5F001%5F000%5F000&Page=1

[Pepsi]

I don't know if this will help you. I have a 24V transformer that controls the water valve on my bong (refill as it gets low) It runs off 120V and puts out 24V with 20 amps ? Let me know I get the specs for you. Size wise it's 2.5" tall and 2.0"X 2.0" heck if they are cheap enough couldn't you tag team 2 of them together?
Just a thought
Pepsi

[71skylark]

Thanks pepsi, that would be useful info if I should try to build my own. I will also need a rectifier and about 70 farads of capacitors to go with it though, but building my own might be the route I have to take.

[ButcherUK]

70 Farads?! Christ you could probably run the thing for a week off the charge in them. Normally you spec 2,000uF per amp, by that calc you're looking for a 35,000A supply.... that's a lot of TECs :D
As for rectifiers, they're pretty easy to find, I'm using a 35A bridge on my rad fan psu atm cos I burned out the 1.5A one with a short and the 35A was to hand ;)

[ButcherUK]

As a quick note by my calcs 70F of caps would keep dual 172W TECs running for about 75s off the charge stored... you might want to scale that back a bit ;)