pelt quesions part deux
 

ok, i have 2 172watters, they are 24v 11amps.


i heard its not good to run them at the rated 24v, what voltage shold i run them at, and what would happen if i ran them at 24v?

also, how would they perform if i ran them at 12v a piece?


i had some more questions but i cant remember what they were now... heheeh :shrug:

Thanks
-Josh

As far as not running the pelts @ spec voltage, I've talked at length with the guys @ tedist about this. They say that is the maximum specified voltage. So while running them @ 24v is not necessarily a BAD thing, you are on the upper edge of what it can reasonably handle. That's why it is usually best to run pelts a little under what they are rated for.

When people run pelts on their 12v line, they are usually spec'd for 13 - 16 volts. So to make a long story short, you most definitely can run them at their upper rating, but dropping the voltage a bit will not have any discernable difference in performance (says the guys @ tedist), and it can increase the life of the peltier.

If you ran them at half voltage, i'm pretty sure they would work at half wattage, but I CANNOT guaruntee that.

-Kev

wow, talk about a quick reply.
thanks

i heard that it was very bad to run at the 24v so thats why i asked. i didnt see how it could be bad to run it at the rated voltage, but the guy who told me that is well known for his wc and pelt knowledge so i had to ge opinions here...

also, i'm goin to be running the pelts off of two atx psus, how could i lower the voltage a volt or two for the pelts, obviously a normal resistor would be good... hehe 172 watts 11 amps? :p
thanks

-Josh

A standard diode takes .6 - .7 volts off the line. I imagine that you could wire a couple diodes to the line the peltiers on. Can anyone verify this?

hey that sounds good, Can anyone confirm this???

thanks for the help kevin... you are the man.

how about leds? i know those eat a few volts.... or those fry if i fed them 11 amps?

yeah you need a resistor before LEDs. They typically eat about 1.4v though.
-Kev

You could use diodes, but at 11 amps you would need to get power diodes and put em on heatsinks. Most diodes that could handle that kind of current are going to be Schottkies, so they'll only drop ~0.4V.

You might be better off doing one of two things - get dirt cheap ATXes that have a pot in them so you can adjust the voltage down

or

better, get a couple of HAM radio p/s on the cheap ;)

(third alternative would be to use FETs to control the voltage and heatsink them)

Ran across this at one of my other hang outs - haven't ever used one, don't know how they are, but they looked interesting:

Variable Pelter controller using PWM

well i'm using the atx psus because they are cheap....

and that varible pelt would be hella tight if ony it werent so much.... o well....

you have any links on using the fets? that be cool to use....

I just got the vpc 225+ controller. I still don't have my pelts, so don't know how well it'll work.

at 24v they aren't very efficient, they will remove the most heat, but produce heaps too. 18v - 20v is about the best compromise

You can also play around with different load resistors at the 5v rails to get the voltage you want. Lesser ohmage higher voltage at the 12v, but the resistors get hotter so get those rated for high wattages.

what if i used 3 lm350 voltage regulators, would that give me control for the pelts since they are rated at 3 amps apeice that would be 12 amps for my 11 amp pelts....