The problem I am having is that I take a 9V battery on the input side and set the booster to output 12V out the other side. When I hook up the peltier unit http://www.icstation.com/product_info.php?products_id=1510#.U1g02FcllYp to the other side the notification led on the booster board bogs down from nice and bright to dim and the board gets really hot to the point if i let it go it would more then likely burn you. Am I creating a short circuit? by hooking it directly to the board like that? How do I fix the problem I am having?
My main goal is to create a little mini fridge that runs off my laptop USB port just boosted enough to support everything I need to run peltier unit, pro mini arduino, led, temp sensor.
Your project is not possible, simply because the output power of a PCs USB port is far too low to run
any kind of peltier based cooling system.
Peltier coolers are power hungry, the particular model you are using pulls 60 Watts which is far beyond the capacity of any
USB port.
Your DC - DC converter is being grossly overloaded.
Thank you guys. This is why im a newbie. I always think things will be easier then they actually really are.
I though it would be possible because of the projects I have seen on the net like this one http://www.instructables.com/id/5-Mini-USB-Fridge!/?ALLSTEPS I guess I could just use a low 5V right off the USB to keep it semi cool? just not to its full potential, or is this a bad idea? I just figured i could boost it between the usb and peltier unit but I guess that is a no go.
This site states running off a usb also Cyber Monday PC component deals | TechRadar. Like I said i just figured instead of the low USB power I could boost it but that is not happening.
I have another idea but i will have to dig out a old laptop charger and see what that output maybe I can just use that and rig something up to suit my needs and have a fridge that plugs in instead of USB. That or lower 12V drill charger for those crappy walmart drills or something.
Let me know if this is plausible or if I should just toss this idea into the trash
The article is very vague about a lot of things.
For example, the type of peltier used.
Most PC USB ports can only supply 500 ma, so a peltier that tries to draw more than 500 ma will cause the USB hub to current limit
or worse, possubly damage it.
5V at 500 ma is only 2.5 watts ,and the normal efficiency of a peltier is around 50% when cooling, so at best the total cooling power available would be only 1.25 watts, which is next to none.
Assuming a 375 ml can of coke and wanting to cool it from 25C to 10C.
The specific heat of water, which coke mainly is , is 4.2 J/G/C needs 4.2 X 375 X 15 = 23625 joules or 23625/1.25 = 5.25 hours to cool the coke down.
This assumes also that the cabinet is perfectly insulated.
You can make peltier coolers, but you need far more power than a USB port can provide, and you need an extremely good
heatsink on the hot side to keep the temperature down.
defcon618:
My main goal is to create a little mini fridge that runs off my laptop USB port just boosted enough to support everything I need to run peltier unit, pro mini arduino, led, temp sensor.
Presumably it will be thermally insulated and have a thermostat so you don't need it to be continuously powered.
You could charge up a big capacitor from your voltage booster then discharge it through the Peltier in huge pulses. All you need is a couple of MOSFETs to control it.
Peltiers are very good conductors of heat when powered down, so for a fridge they
have to be continusously powered otherwise you've just got a coke-can connected
to an external heatsink!
You also need more current to sustain a larger temperature difference across the
device, meaning that running a peltier at 10% nominal level is fairly pointless for
a fridge. Without some mechanical means of decoupling the peltier thermally
you cannot employ a duty-cycle style cooling regime like a standard fridge.
A peltier coupled to a coolant loop with a pump would permit running the peltier
at best efficiency point on a duty-cycle basis, but even so they are woefully inefficient
compared to standard refrigeration technology.