AirPort Extreme (A1143/A1408) Power Supply

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Level 1

4 points

AirPort Extreme (A1143/A1408) Power Supply

I recently purchased an A1408 AirPort Extreme for my network, and realized that the INSIGNIA NS-AC1200 I've used as a replacement with the A1143, has a maximum output of 12V--1300mA (1.3A). According to the Technical Specifications, https://support.apple.com/kb/SP671?locale=en_U, it stipulates12V--1.8A (1800mA). Which even with my limited knowledge of Electrical Power, I know the amount supplied (1300mA) is about 500mA less than what is stipulated (1.8A),

However, despite the replacement adapter having insufficient power (Input: 100-120V~50/60Hz, Set Output: 12V--1300mA) to the stipulated Amperage required (Input: 100-240V~50-60Hz, Output: 12V--1.8A), my A1143 has ran without issue for over a year!

The part I don't understand is how? From what I've read insufficient power from the Power Supply, though usually does not cause harm to the Device, can cause it to be unable to function properly/power-on, as well, the Adapter to overheat/fail. Does the AirPort Extreme not actually require/need the 1.8A Apple stipulates? if not, is it less than 1.3A (1300mA)? what is the actual amount needed? Is there a device function not working/properly functioning that I am missing/unaware? Does the A1408 require the same stipulated amount? could the INSIGNIA be interchanged as the Tech Specs suggest? Do the added features/functions require a greater supply of power? or are they the same/similar between generations?

Thanks in advance in helping me understand what's going on here!!

Posted on Dec 6, 2016 7:39 AM

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Answer 1

Jan Hedlund

Level 7

24,235 points

Dec 6, 2016 12:07 PM in response to enjoy.jer

Generally speaking, the current rating for a device (such as a router) is a maximum value. The actual current used by the device could be lower (for example, depending on the network activity and radio power used at a given time).

However, the power adapter must be capable of delivering the exact DC voltage required by the device (12V for the router in your example) and at least the maximum required current (1.8A in your example). As you also indicated, the use of a power adapter with a lower current rating (for example, 1.3A could lead to overheating and failure (and to an inability to provide the required DC voltage).

In order to avoid a possible overheating, it is important to make sure that the power adapter has a correct output power rating (that is, both voltage and current).

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Answer 2

Dec 6, 2016 3:21 PM in response to enjoy.jer

Just to add..

The apple supply is rated rather higher than required.. particularly for when you need to use 500ma on the USB port.

As long as you have nothing connected to USB the 1.3A rated supply is plenty.

I will also note..

Power supply current rating is usually peak.. so it really should be run at no more than 75% of that value.

Often cheap power supplies rated at 2A are really 1A but can sustain 2A for brief periods..

Apple 1.8A is continuous.. so it is way over rated for this task.. a very good thing and good quality which is why they often outlast the router.

You can buy 12v supplies of any size really.. but 3A or 4A used for LED lights are excellent for using with most 12v routers..

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Answer 3

Jan Hedlund

Level 7

24,235 points

Dec 6, 2016 12:46 PM in response to Jan Hedlund

Addendum

AirPort Extreme 802.11n (5th Generation) - Technical Specifications

Look for labels on routers and power adapters in order to verify input and output voltages and currents.

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