Two 12V devices not working from single 12V 2A adapter

Thread Starter

Tom gayle

Joined Sep 20, 2021
15
Hi,I have two devices 12v 0.18a and 12v 6a(max) and I powered those devices through 12v 2a adapter but that 2 devices didn't work properly.but if I powered one device (12v 0.18a) through 12v 2a adapter it worked more efficient.please say.. what's the reason for 2 devices not working properly?what can I do?please..
 

William Ketel

Joined Jan 23, 2018
16
Was that second device really six amps? If the max is six then the average is probably much more than two amps.
The ratings on the current output of "AC adapters" are usually the absolute max that they can deliver. So there is no way that the six amp device can work with a two amp power supply.
 

Thread Starter

Tom gayle

Joined Sep 20, 2021
15
Was that second device really six amps? If the max is six then the average is probably much more than two amps.
The ratings on the current output of "AC adapters" are usually the absolute max that they can deliver. So there is no way that the six amp device can work with a two amp power supply.
Thank you
 

Thread Starter

Tom gayle

Joined Sep 20, 2021
15
Was that second device really six amps? If the max is six then the average is probably much more than two amps.
The ratings on the current output of "AC adapters" are usually the absolute max that they can deliver. So there is no way that the six amp device can work with a two amp power supply.
Was that second device really six amps? If the max is six then the average is probably much more than two amps.
The ratings on the current output of "AC adapters" are usually the absolute max that they can deliver. So there is no way that the six amp device can work with a two amp power supply.
So,how many volts and amps adapter should I use ?
 

William Ketel

Joined Jan 23, 2018
16
So,how many volts and amps adapter should I use ?
If the device is rated to require 12 volts, then a 12 volt supply is what it should have. As for the required adapter current rating, you stated that it said "6A max". But since we have no information about what the device is or what it's average current requirement is, suggesting an adapter rated at less than six amps carries a bit of risk.
Will the device draw six amps frequently or seldom is unknown until we know what it is. You may get away with an adapter rated for 5 amps..
 

Thread Starter

Tom gayle

Joined Sep 20, 2021
15
AC
If the device is rated to require 12 volts, then a 12 volt supply is what it should have. As for the required adapter current rating, you stated that it said "6A max". But since we have no information about what the device is or what it's average current requirement is, suggesting an adapter rated at less than six amps carries a bit of risk.
Will the device draw six amps frequently or seldom is unknown until we know what it is. You may get away with an adapter rated for 5 amps..
Actually,one device is peltier thermoelectric and another is heatsink with fan.so how many amps should I Power to those devices?
 

Thread Starter

Tom gayle

Joined Sep 20, 2021
15
not really, dont forget he wants to run two devices, a 6A, and a .2A
Personally I wouldn't use less than a 10A supply. An 8A supply would likely work, but without knowing the average draw of the 6A device, it might be risky.
Actually,one device is peltier thermoelectric and another is heatsink with fan.so how many amps should I Power to those devices?
 

Thread Starter

Tom gayle

Joined Sep 20, 2021
15
not really, dont forget he wants to run two devices, a 6A, and a .2A
Personally I wouldn't use less than a 10A supply. An 8A supply would likely work, but without knowing the average draw of the 6A device, it might be risky.
Actually,one device is peltier thermoelectric and another is heatsink with fan.so how many amps should I Power to those devices?
 

ThePanMan

Joined Mar 13, 2020
94
First thing that came to my mind is the 6 amp thing on a 2 amp supply. Not going to work. 6A Max ? ? ? Confusing.

What would happen if you took your lawn mower engine and put it in your car? Could you drive it using a 6 horse lawn mower engine? Probably not. Not enough power.

You mention Peltier module(s). Haven't any experience with those, so perhaps under "Max" conditions it could draw 6 amps. So when engineering a solution you should always strive for "Overkill". If your circuit draws 6 amps then you should design for a minimum of 9 amps (150%). Plus the fan you want to drive, 9A would be sufficient. But keep in mind that some power supplies come from dubious sources and can represent false facts. I've seen 10 amp supplies that couldn't push more than 6 amps. I make a random example, but this is the sort of thing I've seen. Go with reputable sources.

If you want to test your circuit to see if it works - go to your car and connect to the car battery. I bet everything works as you want it to.
 

William Ketel

Joined Jan 23, 2018
16
The Peltier cooler will draw a fair amount of current, and that "6a max" is because the makers had no idea what the specific device would draw, because the cheap ones do vary. So the reality is that it will draw some current constantly that might be as much as 6 amps. The fan on the heatsink will draw it's rated current or very close to that. Quite likely a six amp supply will work. It does not need to be a regulated supply, just a fairly close to 12 volt is OK. AND it does not need to be well filtered, because the Peltier cooler does not care about ripple on DC.
 

Thread Starter

Tom gayle

Joined Sep 20, 2021
15
The Peltier cooler will draw a fair amount of current, and that "6a max" is because the makers had no idea what the specific device would draw, because the cheap ones do vary. So the reality is that it will draw some current constantly that might be as much as 6 amps. The fan on the heatsink will draw it's rated current or very close to that. Quite likely a six amp supply will work. It does not need to be a regulated supply, just a fairly close to 12 volt is OK. AND it does not need to be well filtered, because the Peltier cooler does not care about ripple on DC.
So,can I use 6a or 3a or 5a or 8a?and also my heatsink fan takes 0.18a.therefore how many amp is required?
 

William Ketel

Joined Jan 23, 2018
16
So,can I use 6a or 3a or 5a or 8a?and also my heatsink fan takes 0.18a.therefore how many amp is required?
Certainly an 8amp supply would be adequate, the load will only draw what current it requires. And if the peltier cooler draws exactly 6.00 amps then with the fan drawing an additional 0.180 amps there will be a bit of spare capacity.
 

djsfantasi

Joined Apr 11, 2010
7,867
So,can I use 6a or 3a or 5a or 8a?and also my heatsink fan takes 0.18a.therefore how many amp is required?
I definitely wouldn’t use a 3A or 5A supply. Neither are MORE than 6A. Note that when selecting a power supply, the amp rating needs to be MORE than the amps required. If they are matched it MIGHT work for SOME time, but can’t be guaranteed to work reliably. Hence, IMHO I’d never use a 6A supply for a 6.18A load.

That leaves the 8A or greater supply, that’s been tested to actually provide 8A.

Or you can pick another supply and hope that it works.
 

Travm

Joined Aug 16, 2016
348
There are some nifty text books on this website that will educate you on how electricity works. You should spend a few hours reading these before you burn your house down.

My recommendation is 10A. Especially if you will be using this for any amount of time more than quick on, then turn off.
 

vu2nan

Joined Sep 11, 2014
188
The following typical specifications of a Peltier element would help in sizing the power supply.
  1. Model number: TEC1-12706
  2. Operating Voltage: 12V
  3. Maximum Voltage Umax (V) : 15.4V
  4. Maximum Current Imax (A) : 6A
  5. Maximum Power: 92 W
Exceeding the maximum ratings would damage the element (15.4 x 6 = 92.4).

A study of the performance specifications shows that the Peltier element behaves like a resistor with a positive temperature coefficient.

1.JPG

The graphs show only a marginal influence of hot / cold side temperatures (∆ T) on the current consumption (4.5 A at 12 V).

The calculated value is = (12 / 15.4) * 6 = 4.68 A.

It would not be wrong to conclude that a regulated 12 V DC 6A power supply would be more than ample to power the module as well as the cooling fan.

Nandu.
 
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