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The charger that came with my iPad Air the square adapter that plugs into the socket stays warm even when nothing is connected other than that it works perfectly fine.

I was wondering if this phenomena is normal or is not good worse yet. My biggest fear is it a fire hazard?

While my iPad is connected the charger stays the same warm temperature. It doesn't get hot per se, or else I haven't noticed get too too hot but it stays warm whether I'm charging my iPad or not.

So what's up? Is this normal? Should I be concerned? Is is safe to leave the iPad charger plugged into the socket all the time?

  • 1
    It'd be helpful if people who have both an iPad (air), and a wattage meter supplied some actual values for standby power usage. My old iPad (v1) charger pulls 0.0 watts from the wall when nothing is plugged into it. Good wall warts are like that. I'd be suspicious of anything that pulls enough juice to stay warm, much less hot when it's not doing anything. – Wayfaring Stranger Jun 23 '14 at 14:45
  • @WayfaringStranger - best answer here: let's get the watt meter readings, rather than "it's normal" – tim Aug 30 '14 at 23:15
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Assuming that the wall socket is providing power (or the switch for the socket is on) it is normal, or rather common, for power adapters of devices to be a bit warm when connected to the wall socket (mains) without a device connected to the other end (iPad, iPhone, laptop, etc.). In many cases, the charger would be considerably warmer while actively charging a device than when it's not.

Here's additional information broken down into bullet points:

  • The amount of heat produced primarily depends on the size of the adapter, its charging capacity and its build quality (there are other secondary factors as well).
  • Heat is a product of resistance in electrical and electronic circuits, and is observed in every electrical/electronic equipment to varying degrees.
  • All power adapters have a "transformer" that first converts the high mains AC (alternating current) voltage, which would be 230V or 110V, to a much lower voltage, which is then converted to DC (direct current) and fed to the device.
  • An ideal transformer and power supply would not produce heat when nothing is consuming power on the other end. But practically, all transformers (and power supplies) have losses of different kinds (although this has improved over time), and this not only results in heat, but also results in minuscule amounts of power being used even when no device is connected to the adapter.
  • If you find the adapter being too hot to touch, then it's malfunctioning or failing. If it's only a bit warm, there's nothing to worry about except for an increase in your electricity bills (however small).
  • As for fire hazard, it's always better to turn off the mains switch (or unplug if there's no switch to control it) on all electrical equipment when not in use and also keep them away from flammable items (or items that may catch fire after prolonged exposure to heat).
  • If the charger overheats during usage, Apple's genuine chargers have built-in protection to turn them off.

For more information, see:

  1. Wikipedia article - Real transformer - deviations from ideal
  2. iPad charger teardown (Ken Shirriff's blog)
  • Actually, AC power supplies these days are usually switched mode: they use electronics and rectifiers rather than a transformer. These are smaller and lighter but the main advantage is that such a power supply can work with multiple voltages (e.g., 110V in north America and 230V in Europe). If the adaptor did use a transformer then an adaptor that produced 5V in north America would produce 10+V in Europe, potentially frying your equipment. Also, unlike transformers, even an idealised switched mode power supply draws current when idle. – David Richerby Jun 23 '14 at 12:17
  • @DavidRicherby Still, they do use smaller transformers before their switching circuit. And, IIRC, the 110/220V switch switches the input of the transformer, not some control input of switching cicuit — at least in the supplies I disassembled. – Ruslan Jun 23 '14 at 13:15
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    @DavidRicherby, there are transformers in power supplies. It's just that they're no longer as bulky as they used to be before the advent of switched mode power supplies. I'm adding this link that shows a tear down of an iPad charger (from May 2014) to the answer for clarity: righto.com/2014/05/a-look-inside-ipad-chargers-pricey.html – M K Jun 23 '14 at 14:50
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Getting warm is pretty normal, as 230 Volt or 110 Volt are converted to the iPhone/ipad needs.

On top of that, if it's fire hazard the charger shouldn't work anymore or work very poorly, but since you didn't write that as problem you can exclude fire hazard (at this stage).

I would recommend not leaving any charger plugged in if you're not using it (for charging purposes) at that current time.

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Testing iPad square adapter (Model A1401).

Left plugged-in but not connected to iPad for 12 hours.

Consumption = 0 watts (measured by Belkin watt meter power socket).

So perhaps they've improved the design. But this was cold to the touch and consuming zero standby power.

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protected by bmike Mar 9 '15 at 17:35

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