How many Peltier elements can I use in my power outlet?

[HomeExperiement]

Hi!

I want to build some cooling with peltier elements. At home I get 230V from power outlet and the maximum allowed power consumption is 15A. However, when I look at peltier elements at online store I notice that amps go up fast. Like some 12V 180W peltier is already 15A. Does this mean that I can really only connect 1 peltier per outlet? I heard once one hint that 15A @ 230V is not same as 15A @ 12V. But now I would like to know what are my limits then? For example if I buy myself 600W PSU and connect there 3x 180W peltier. The load would be 540W which is below what PSU is rated for. So there should be a problem? However what makes me worried is that when I look at amps, then it would be 3x15 = 45 Amps. So my question is what would happen if I plugged in 600W PSU with 3x 15A peltier elements? Would it burn down my house or not? In other words, would my 230V outlet get 3x15=45A load? Or would converting it to 12V do some magic that I am not aware of it and it would be ok to plug it in?

 

[russ_watters]

Welcome to PF!

I want to build some cooling with peltier elements.

To cool what?

At home I get 230V from power outlet and the maximum allowed power consumption is 15A. However, when I look at peltier elements at online store I notice that amps go up fast. Like some 12V 180W peltier is already 15A. Does this mean that I can really only connect 1 peltier per outlet?

Yikes! Peltier modules are DC current, not AC current. You *cannot* plug them directly into power outlets.

I heard once one hint that 15A @ 230V is not same as 15A @ 12V.

Certainly no. It seems like you don't know the very basics of electricity, and you really need to before tacking even a low voltage project. You should learn about what voltage, current, resistance and power are and what their relationships are. Go through at least the first three sections of this:
https://www.allaboutcircuits.com/textbook/direct-current/chpt-2/voltage-current-resistance-relate/

But now I would like to know what are my limits then? For example if I buy myself 600W PSU and connect there 3x 180W peltier. The load would be 540W which is below what PSU is rated for. So there should be a problem? However what makes me worried is that when I look at amps, then it would be 3x15 = 45 Amps. So my question is what would happen if I plugged in 600W PSU with 3x 15A peltier elements? Would it burn down my house or not? In other words, would my 230V outlet get 3x15=45A load? Or would converting it to 12V do some magic that I am not aware of it and it would be ok to plug it in?

I'm going to let you take a shot at answering that yourself after you take some time to go through the online textbook I linked above.

 

[HomeExperiement]

To cool what?

It's not important at the moment, let's keep the topic at original question. Otherwise we will have millions of opinions on whether or not peltier elements are suitable or not while the original question is still unanswered.

Certainly no. It seems like you don't know the very basics of electricity,

An you certainly did not read my post. Can you find a place where it says that I plan to connect these directly to wall outlet? Do you know that such thing as PSU exists? Can you guess why I mentioned it?
You start judging before you even read to the end. You certainly didnt even try to understand the question. I would encourage you to first read and understand my entire post, not just one sentence of before you start to type something.

Thank you.

 

[russ_watters]

An you certainly did not read my post. Can you find a place where it says that I plan to connect these directly to wall outlet?

It's right here:
"At home I get 230V from power outlet and the maximum allowed power consumption is 15A. However, when I look at peltier elements at online store I notice that amps go up fast. Like some 12V 180W peltier is already 15A. Does this mean that I can really only connect 1 peltier per outlet?"

These sentences show a misunderstanding of electricity, but it isn't totally clear what that misunderstanding is. Since you haven't mentioned the PSU at that point, reading them alone implies you may be intending to connect them directly to the outlet. It is best to describe completely your setup before asking your question.

Do you know that such thing as PSU exists?

Certainly. But it seems from your question that you don't know what a PSU is or what it does. That seems like the main focus of your question.

You start judging before you even read to the end. You certainly didnt even try to understand the question. I would encourage you to first read and understand my entire post, not just one sentence of it and then post replies here.

So, now that we've cleared-up that you are using a PSU, nothing else about my reply changes. Look: you're here because there are things you don't know. And you may not even know how much you don't know. Or how not knowing inhibits your ability to communicate what you know and don't know. There's nothing inherently wrong with that, but you can't simultaneously be wanting help to correct your misunderstandings and get mad about those misunderstandings. So would you like help or not?

 

[anorlunda]

Settle down. @russ_watters was trying to help you.

I know what a power supply is, but I had to Google the acronym PSU.

The basic electricity fact you're missing is power = voltage times current. So 120V * 15 A = 1800 watts.
Conservatively estimate the PSU is 50% efficient.
You take it from there.

 

[russ_watters]

It's not important at the moment, let's keep the topic at original question. Otherwise we will have millions of opinions on whether or not peltier elements are suitable or not while the original question is still unanswered.

Fair enough. I'm a mechanical engineer and I've done several Peltier cooling projects, so I may be able to provide some help with the project itself you want that at some point.

 

[HomeExperiement]

So would you like help or not?

yes, I would like to get help. But maybe from someone else.

As I mentioned above PSU. And how I plan to connect peltiers there and my question about it.

 

[Guineafowl]

Hi!

I want to build some cooling with peltier elements. At home I get 230V from power outlet and the maximum allowed power consumption is 15A. Power is not measured in amps. However, when I look at peltier elements at online store I notice that amps go up fast. Like some 12V 180W peltier is already 15A. Does this mean that I can really only connect 1 peltier per outlet? I heard once one hint that 15A @ 230V is not same as 15A @ 12V. This is correct, but if you didn’t know that, but only heard it, this reinforces Russ’ opinion. But now I would like to know what are my limits then? For example if I buy myself 600W PSU and connect there 3x 180W peltier. The load would be 540W which is below what PSU is rated for. So there should be a problem? However what makes me worried is that when I look at amps, then it would be 3x15 = 45 Amps. So my question is what would happen if I plugged in 600W PSU with 3x 15A peltier elements? Would it burn down my house or not? In other words, would my 230V outlet get 3x15=45A load? Elementary knowledge of P=IV would give you the answer. Or would converting it to 12V do some magic that I am not aware of it and it would be ok to plug it in?

Russ wasn’t getting at you, but there are significant gaps in your knowledge that are apparent from your questions. We all have to start somewhere - have a good look at the links he’s provided.

 

[russ_watters]

The basic electricity fact you're missing is power = voltage times current. So 120V * 15 A = 1800 watts.
Conservatively estimate the PSU is 50% efficient.
You take it from there.

I'll add to that, that one essential component of a power supply is a transformer, which should help explain what it is doing (for the OP): https://en.wikipedia.org/wiki/Transformer

 

[Guineafowl]

Here are some numbers for you:

At the outlet, you have 230V and 15A. P = IV = 15x230 = 3450W.
The 12V and 15A Peltier draws P = IV = 12x15 = 180W.

So there is plenty of power available at the socket to run several Peltiers.

Power is a rate of delivery of energy and is measured in joules per second, or watts. Electrical power is the product of voltage and current (P=IV) and so both need to be taken into account when assessing power requirements.

A useful aide-memoire from school physics was PIV-VIR-QIT (pronounced ‘pivverkit’) and helps you remember P=IV, V=IR and Q=IT.
P is power (W)
I is current (A)
V is voltage (V)
R is resistance (ohms)
Q is charge (coulombs)
T is time (seconds).

 

[HomeExperiement]

I know what a power supply is, but I had to Google the acronym PSU.

The basic electricity fact you're missing is power = voltage times current. So 120V * 15 A = 1800 watts.
Conservatively estimate the PSU is 50% efficient.
You take it from there.

120V *15A = 1800W. If PSU is 50% efficient then through PSU. I can get 900W power right? So in theory I can plug there 5x 180W peltier? Well to avoid loading it to max let's say 4x.

And wall socket where PSU is connected doesn't see it as 4x15=60A load? The reason I am asking this is because I want to be sure. I don't just want to read the theory and then assume that now I can start doing stuff. In other words, I could read these articles in the world and in real life still mess something up and that's why I came to ask here.

 

[Guineafowl]

120V *15A = 1800W. If PSU is 50% efficient then through PSU. I can get 900W power right? So in theory I can plug there 5x 180W peltier? Well to avoid loading it to max let's say 4x.

And wall socket where PSU is connected doesn't see it as 4x15=60A load? The reason I am asking this is because I want to be sure. I don't just want to read the theory and then assume that now I can start doing stuff. In other words, I could read these articles in the world and in real life still mess something up and that's why I came to ask here.

Your supply is 230V, so adjust calcs to suit. Assuming 100% efficiency, you can run just over 19 Peltiers on one socket (3450W/180W). Even at 50% it’s still 9 or so.

The wall socket does not ‘see’ the 15A, 12V load as equivalent to 15A, 230V, no. When you drop the voltage (230V->12V) you can increase the current. P=IV P=IV P=IV. Burn the equation into your brain.

 

[HomeExperiement]

Btw how should I unerstand 50% efficiency of PSU? Does it mean 100W PSU at max load consumes 100W from power socket and gives me out 50W? Or does it mean that 100W PSU gives me 100W at max load but draws 200W from my wall?

Also what happens if I plug 200W peltier in 100W PSU? Does PSU burn in or does it simply run peltier on half of it's power or does some firmware simply turn them off?

 

[CWatters]

Btw how should I unerstand 50% efficiency of PSU? Does it mean 100W PSU at max load consumes 100W from power socket and gives me out 50W? Or does it mean that 100W PSU gives me 100W at max load but draws 200W from my wall?

Eff% = 100 * power out/power in

So both situations are 50% efficient.

Power supplies are normally rated on their output so a 100w PSU can output 100w. If you connect a 100w load it will draw 200w from the mains. If you connect a 75w load it will draw 150w. Etc.

Also what happens if I plug 200W peltier in 100W PSU? Does PSU burn in or does it simply run peltier on half of it's power or does some firmware simply turn them off?

It depends on the PSU. It might switch off. It might blow a fuse. _If_ it is designed correctly to modern safety standards it should not catch fire but it's not a good idea to test this.

 

[anorlunda]

I removed a side-topic that IMO was too advanced for the OP to perform safely. We have many experts on these forums, but we must be careful to not recommend an expert solution to beginners.

 

[HomeExperiement]

I removed a side-topic that IMO was too advanced for the OP to perform safely. We have many experts on these forums, but we must be careful to not recommend an expert solution to beginners.

Basically my question was if PC PSU is fine to power peltiers?

 

[CWatters]

Basically my question was if PC PSU is fine to power peltiers?

Yes. You can power 12V peltiers from the 12V rail of a PC Power supply. They should all be connected in parallel.

However before you buy a 600W power supply check how much current you are allowed to draw from the 12V rail(s). The 600W power figure is the total for all voltage rails. Not all power supplies will let you draw the full 600W (= 50A) from the 12V rail.

Some power supplies also get unhappy if there is no load on the other outputs (eg there is a minimum current draw as well as a max.).

You will also need to link two pins on the connector to get it to turn on...

https://www.overclockersclub.com/guides/atx_psu_startup/

PS: Some power supplies have one 12V rail inside feeding several output wires. Other power supplies have multiple 12V rails inside. If yours has more than one 12V rail you need to share the load across all of them.

 

[Lord Crc]

I'd be more worried about how to get rid of the heat from 4x180W peltiers. The solder in the ones I've got starts to melt at 138 degrees C...

 

[metiman]

Yes well I predict tall heatsinks with loudly buzzing fans in his future. The whole point of the things is to give off heat. How about buying a bunch of water blocks and using water cooling?

 

[HomeExperiement]

However before you buy a 600W power supply check how much current you are allowed to draw from the 12V rail(s). The 600W power figure is the total for all voltage rails. Not all power supplies will let you draw the full 600W (= 50A) from the 12V rail.

Did you mean from single 12V rail? Not exactly sure what rail is because english isn't my first language but I guess its a plug where I can get 12V? Doesn't computer PSU have several of these? That way single PSU socket would not have to deal with 50A. Also what happens when I put more than 12V peltier in PSU? Like 15V?

 

[Lord Crc]

A typical ATX computer PSU has indeed several cables with connectors supplying 12V. However internally some PSUs connect them all to a single point ("single 12V rail") so they all share the same regulator, while others split them into typically two or three groups, where each group has its own regulator ("split 12V rails").

With a split rail design you're limited to how much each regulator can supply. Typically you'll see "12V1 20A / 12V2 10A" or something along those lines on the side of the PSU. Here the second 12V group is limited to only 10A.

 

[Lord Crc]

Also what happens when I put more than 12V peltier in PSU? Like 15V?

A Peltier element acts as a resistor (with a large temperature coefficient). The 15V rating is the maximum supply voltage.

It's entirely fine to supply less than the maximum. In that case the current will be reduced as well.

edit: Typically the datasheet will show performance curves for various voltages.Note that the resistive losses (I^2*R) means that if you have inadequate cooling of the hot side you'll be better off running the element with a reduced current (and thus voltage).

 

[HomeExperiement]

PSU has indeed several cables with connectors supplying 12V. However internally some PSUs connect them all to a single point

But how those cable manage 600W? I mean ok they all connect to single point that is designed to withstand 600W but what about the individual cables? I was just afraid that connecting 600W to single cable might melt insulation on wires as these cable doesn't seem to be too big in diameter. like 1 or 2 mm diameter or so.

 

[CWatters]

600W is 50A at 12V.

You only need 5 wires carrying 10A each or 4 wires carrying 12A each. No problem.

 

[Lord Crc]

This is the reason powerful graphics cards have one or two extra power connectors. Each connector has 6 or 8 pins, and deliver several 12V cables each (the remaining cables are ground). for a maximum of 75W (6 pins) or 150W (8 pins).

Lots of details here: http://www.playtool.com/pages/psuconnectors/connectors.html

 

[Guineafowl]

But how those cable manage 600W? I mean ok they all connect to single point that is designed to withstand 600W but what about the individual cables? I was just afraid that connecting 600W to single cable might melt insulation on wires as these cable doesn't seem to be too big in diameter. like 1 or 2 mm diameter or so.

You need to consider current when assessing cables, not power.

Let’s say the cables have a resistance of 0.2 ohm

Imagine 600W being carried as 1A at 600V. Power dissipation (heating) will be 1².0.2 = 0.2 W.
Imagine 600W being carried as 600A at 1V. P=I²R = 600².0.2 = 72 kW.

BIG difference.

 

[davenn]

But how those cable manage 600W? I mean ok they all connect to single point that is designed to withstand 600W but what about the individual cables? I was just afraid that connecting 600W to single cable might melt insulation on wires as these cable doesn't seem to be too big in diameter. like 1 or 2 mm diameter or so.

you didn't read the response given to you on page 1 of the thread

eg. A 600W PC PSU is the total rating
NOT the rating of anyone of the DC rails ... 3.3V, 5V, 12V etc

Usually the 5V and the 3.3V rails have the highest current capabilities the +12V somewhat lower and the -12V very low current capability

lets look at an example ...

OK on this particular one, you can see that it has 2 x +12V outputs, each one capable of 17A
so there is your max and you DO NOT want to run at that max of 17A each ... it will shorten the life of the PSU

So you could run 2 x 12V / 15A peltiers, one on each line

Get a higher rated PSU and you may be able to get a second peltier on each 12V rail

600W is 50A at 12V.
You only need 5 wires carrying 10A each or 4 wires carrying 12A each. No problem.

see my previous comments in this post ... that 600W is the total capability of a particular PC PSU

If @HomeExperiement really need many high current peltier units and not just a couple then he needs to look at a
specific 230AC-12VDC PSU that is capable of supplying the needed currentDave

edited for extra comments

 

[davenn]

I know what a power supply is, but I had to Google the acronym PSU.

ohh my, really ?

 

[sophiecentaur]

Did you mean from single 12V rail? Not exactly sure what rail is because english isn't my first language but I guess its a plug where I can get 12V? Doesn't computer PSU have several of these? That way single PSU socket would not have to deal with 50A. Also what happens when I put more than 12V peltier in PSU? Like 15V?

I am fresh into this thread but, having read your posts and you reaction to being 'corrected' I would say that you risk spending a lot of money here and get nowhere useful. You still seem not to understand fully that a low voltage, high current PSU will take a low current from a high voltage (mains) supply. If you want any success in Electrical Projects, there are a number of basics that you really need to understand. I can see that many of the responses you have been given here are probably too hard for you to understand fully - that tends to happen on PF. In my opinion, what you need is a source of basic information about Electrical Theory. The best choice for you will depend on your first language but you are sure to be able to get hold of a School Text Book which is aimed at, say 14 years upwards. If the easy stuff is too trivial for you than never mind - you can find other stuff in the book or move upwards.
I make this comment on a frequent basis: "Question and Answer is not the way to learn any of Science effectively." Q and A may work well to supplement an existing learning course.

 

[HomeExperiement]

In my opinion, what you need is a source of basic information about Electrical Theory. The best choice for you will depend on your first language but you are sure to be able to get hold of a School Text Book which is aimed at, say 14 years upwards.

Books be like "Ok, here are 300 pages of formulas, now go ahead and figure all your projects out by yourself." And by the end of the book you'd still be asking here the same questions lo learn how things actually work. In these replies to my topic there weren't a formula that I did not learn at school.

 

[sophiecentaur]

Books be like "Ok, here are 300 pages of formulas, now go ahead and figure all your projects out by yourself." And by the end of the book you'd still be asking here the same questions lo learn how things actually work. In these replies to my topic there weren't a formula that I did not learn at school.

You are making assumptions about 'all books'. You may not like the Maths of Science but, if you agree that it helps a lot to use arithmetic to keep tabs on your finances then the same thing applies to 'Scientific' projects. They all need some formulae and calculations - if you want to avoid a dumpster full of failed equipment.

 

[krater]

P=IV P=IV P=IV. Burn the equation into your brain.

Easier to do with this equation: P=IE

P=IE P=IE P=IE

Come on now which of these series are easier to remember?

 

[sophiecentaur]

Easier to do with this equation: P=IE

P=IE P=IE P=IE

Come on now which of these series are easier to remember?

I'm very partial to a bit of Steak and Kidney PIV and chips, aamof.

 

[Guineafowl]

Easier to do with this equation: P=IE

P=IE P=IE P=IE

Come on now which of these series are easier to remember?

Which is better:

PIVVIRQIT
Or
PIEEIRQIT

?!