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I've borrowed a 2015 MacBook Retina to process Go Pro 360 videos because there's no Linux software to do this.

The power supply gets excessively hot and I feel this is not normal. When the laptop is idle, the power supply is barely warm, but when doing video work for 20+ minutes, this results:

Infrared image of a MacBook power adapter

Possibly related, the battery menu says "Service required" but the laptop runs on battery adequately well, considering its age.

The ambient temperature is around 18 degrees C and the exterior case of the power supply measured 83.7 degrees C.

I suspect this supply is not an Apple original. It's labelled underneath:

Replacement AC Adapter
Model No. A1222 / A1290 / A1343
INPUT AC 100V-240V~1.5A 50-60 Hz
OUTPUT: 18.5V =-= 4.6A
20V =-= 4.25A CE 85W

What are the possible consequences of running an AC adapter this hot?

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    The genuine Apple adapters are designed to blow an internal fuse long before it gets too hot to be dangerous, you’ll be safe
    – Allan
    Commented Jun 5, 2023 at 0:57
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    Be careful. I got third degree burns on my leg from one while I was asleep. It basically cooked my calf muscle and I had to get surgery. It took months to heal.
    – Kalamalka Kid
    Commented Jun 5, 2023 at 3:57
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    What is the ambient temperature and also the coolest temperature in dim purple / violet (perhaps on the corner or the cord)?
    – bmike ♦
    Commented Jun 6, 2023 at 12:29
  • @bmike ambient/background temp would be around 18 degrees C. In other words, this PSU was too hot to hold to unplug from the socket, even briefly.
    – Criggie
    Commented Jun 6, 2023 at 13:16

2 Answers 2

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Stop using it.

A charger, regardless of the brand, should never be hot to the point where it can cause injury (84°C could) or become a cause for concern.

First, stop using it. Then, I strongly recommend you to get support and eventually bring it to an Apple Store to get a clear idea of what to do (they are more likely to tell you to replace it).

What are the possible consequences?

You as well as objects in your environment could get severely burned. You might also experience, in extreme cases, your charger melting or your wire becoming frayed or burned. In this case, you will have to replace your charger for sure because of security purposes.

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    Incorrect. A charger cannot damage the battery. The service battery warning is likely due to a battery that has already failed, not this charger; which is within the safety envelope specified by IEC/UL. Why are you directing folks to support to potentially spend money on a problem which doesn’t exist?
    – Allan
    Commented Jun 5, 2023 at 19:54
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    @Allan Thx for pointing this out. I've edited the answer. Is it alright now?
    – Thinkr
    Commented Jun 6, 2023 at 5:11
  • @Thinkr don't sweat the downvotes - they're a fact of life on SE. I won't be getting Apple support on an 8 year old laptop, but a replacement PSU seems wise.
    – Criggie
    Commented Jun 6, 2023 at 13:14
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    @Criggie They still seem excessively hight for an unknown reason (4 downvotes in less than 1 day...).
    – Thinkr
    Commented Jun 6, 2023 at 13:46
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The product is within spec.

The maximum allowable temperature for IT equipment (ITE) is 95°C.

Given that the recorded temperature is a bit high at ~84°C, it’s well within the UL and IEC specifications to qualify as “safe” (with respect to the temperature test).

enter image description here

Surface Temperature Limits in Normal Conditions1

Granted, the recorded temperature is in on the high side, but that will depend on the manufacturer’s stated operating range (everything is behind a paywall including UL certifications).

Always use genuine Apple chargers

Apple does not label its adapters as replacement, so you clearly have a third party adapter. Apple parts should run cooler than yours - perhaps significantly as your ambient temperature is very cool and the 66°C (150°F) increase in temperature to dissipate the heat it's generating indicates less money went into it's design / efficiency than an Apple adapter.

All power adapters produce heat to convert AC (mains) power to the DC current the computer (Mac, in this case) uses. Part of that conversion results in energy being dissipated as heat. This is dependent on (at minimum) two factors: current flow and efficiency. The more current that flows, the more heat is generated. The less efficient the conversion, the more heat.

So, if you have a knock-off adapter not as efficient as the genuine adapter, it will generate more heat as you use it increasing the surface temperature of your device. Quality adapters are designed with switchable fuses that will trip in the event of too high a draw to prevent thermal events. Cheaper adapters won’t have this or won’t be as tolerant (higher operating temperatures).

To ensure you get the safest possible component, always go genuine or from an known good OEM supplier (i.e. Delta Electronics).

Applicable Codes

The UL60950-1 standard that covers this type of equipment:

This standard is applicable to mains-powered or battery-powered information technology equipment, including electrical business equipment and associated equipment, with a RATED VOLTAGE not exceeding 600 V and designed to be installed in accordance with the Canadian Electrical Code, Part I, CSA C22.1-12; General Requirements - Canadian Electrical Code, Part II, CSA C22.2 No. 0-10; the National Electrical Code, NFPA 70-2014; and the National Electrical Safety Code, IEEE C2-2012.

The IEC 60950 also defines this type of equipment:

This part of IEC 60950 is also applicable to:

external power supply units intended to supply other equipment within the scope of this part of IEC 60950;

1 Product safety Testing Limits Risk of Shock, Fire, and Injury, EDN.com; March 15, 2013

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  • Maybe - Consider this is the external temperature. Inside will doubtless be hotter, but unknown exactly how hot.
    – Criggie
    Commented Jun 6, 2023 at 13:13
  • @Criggie- Maybe? That’s a given; read further in the UL code for testing and there’s a section on the internal PCBs. This question and the data provided are for the external enclosure which is what this answer directly addresses.
    – Allan
    Commented Jun 6, 2023 at 13:33

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