12v 2a can power 12v 3a?

I ordered an ifi ipower x 12v 2a to power my router which is 12v 3a. Is it a problem or it should work?

You could end up with a burnt power supply, and/or the router itself might not function correctly.

It could work if the router is rated very conservatively, but buying an underrated power supply is a mistake.

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You´re right. It depends on what current the router consumes. @frenchrooster What router are you talking about?

The router is a commercial tv/ Ethernet/ phone fiber box, that provides internet.
The real specs, I checked under the SMPS, are : 12v. 2,5 a.
Do you think that the Ifi power, 12v 2a, will be enough?

No, if the router consumes 2,5 A in real life the ifi PSU is definetly too small. But if I have a look at the fiber box I´ve got from my ISP the manual states it consumes 20 watts when operated, what would make the ifi PSU a quite good fit.

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Ok, will cancel my order. Thanks.

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Current ratings marked on equipment can be very misleading, they are usually too high. A few years ago I spent a bit of time measuring stuff around the office and at home importantly during different operation conditions, startup, full load and quiescent conditions, plus summed averages.
So if you can measure the load that would be helpful.

Either way I would not size a LV power supply close to the Actual load, give it some headroom.

Audiophonics. 12v / 5a

Caractéristiques :

  • Boîtier : 100% Aluminium brossé et sablé
  • Anodisé noir
  • Tension d’entrée: AC 220V
  • Tension / courant de sortie: 12V 5A DC (7,5A en crête)
  • 1 sortie Jack DC 5.5 / 2.1mm
  • 1 sortie jack DC 5.5 / 2.5mm
  • Embase IEC avec porte fusible
  • Transformateur 100VA
  • Régulateur de tension LT1083

Should it power correctly 12v / 2a?

Given that most will have neither the means nor the inclination to go around their house taking measurements, I would suggest when selecting an alternative PSU just to stick to the simple rule: check the output of the supplied PSU, or the input spec of the device. One or the other is nearly always printed on the device. Then select your alternative to have the same voltage, and the same or slightly higher Amp output.

As 5A is higher than 2A, yes, although I’m not sure why they also quote a 7.5A max.

Yes. The voltage must be matched, so 12V and 12V. The current required by your device, 3A must be available from the power supply, so a minimum of 3A. 5A gives you some headroom. So basically the V ratings must be equal and the A rating of the power supply needs to be at least equal to and ideally a bit higher than the A requirement of the device. (Don’t get carried away and have a 100A power supply on a 1A device.)
This just covers the specs, it does not say if the power supply is any good.

Of course in the interests of safety I agree, one has to make a judgement of ones own abilities.

However you can buy ‘Meter’ plug adaptors which allow you to plug your Mains appliance In to it, then plug the ‘Meter’ into the wall socket, this allows the average home owner To work out how much power each appliance uses In the interests of working out the worst offenders. They can read out in power which gives a good insight.

Headroom? It’s positive or negative?

Sorry, I should have been clearer. The current (A) rating on the device is the amount it needs. The current (A) rating on the power supply is the amount it can deliver. So the A value on the power supply must be equal to or higher than the A value of the device.

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Exactly as he said

Provided the voltage is correct, a power supply will not ‘push’ more amps (current) than the unit can take, but the power supply must be capable of ‘giving’ the current (amps) That the unit uses, or might use at peak demand. So the power supply can safely have a bigger current (amp) capability than the unit it is to power, not the other way round.

I think that means a peak power, so 5A constant and OK if it goes to 7.5A briefly sometimes, although I don’t understand en créte in that context.



Crête is Pic current. Just the translation, not the understanding.

It says the voltage regulators are designed to deliver 5 A at 12V but with the given transformer (100VA = 100 watts) the output current requested over a very short period (in order to manage peaks in consumption) can be higher (up to 7,5A).

This PSU is heavily overdosed for a simple ISPs router. However it will work but beeing far away from something pragmatic and efficient.

Can you please post the name and model of your router?

You need to really check the specs for the router to determine the true power requirements or, as mentioned, use one of those cheap mains power measuring plug in thingies. Often manufacturers will standardize on one power supply for all their products so they’ll simply stock any power supply which is powerful enough for all their products - means a better qty price and simplifies stock control. Further they will often simply get any power supply which is cheapest even if it’s over speced for the job. So you might well find it doesn’t need a 2.5 or 3A PSU.

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