MacBook charger teardown: The surprising complexity inside Apple's power adapter (2015)

Original Article ↗ Hacker News Discussion ↗

Age of article & related links

  • Thread notes the teardown is from 2015 but still seen as a “classic.”
  • People link to newer GaN charger teardowns and Apple’s newer 70W GaN charger, plus ChargerLab videos and past HN threads.

GaN chargers and size/weight

  • Several commenters compare old Apple bricks to modern GaN USB‑C chargers (Anker, Dell, others) that are much smaller and lighter for equal or higher wattage.
  • GaN is credited with allowing smaller, more travel‑friendly bricks, though Apple’s GaN units are said to be less compact and less cheap than third‑party options.
  • Multi‑port GaN chargers are popular, but people warn about dynamic power sharing: you may not get full rated power to one port when others are in use.

Grounding, tingling sensations, and EMI

  • Discussion around MacBook chargers producing a “weird buzzing/tingling” sensation on ungrounded setups.
  • Explanation: class II / ungrounded supplies use Y capacitors from both mains conductors to the secondary to shunt EMI, causing a harmless but noticeable stray voltage up to about half mains on device metalwork.
  • Some users switch to 3‑prong cords to avoid tingling; others accept it as inherent to this design.

“Full speed” charging and wattage

  • Debate over what “full speed” means:
    • One view: “full speed” = what the laptop can technically draw at some part of the charge curve (e.g., 45W+ on M1 Air, 140W on some MacBook Pros).
    • Another view: “full speed” = as fast as the stock charger, so a 30W third‑party brick is “full speed” for an M1 Air that ships with 30W.
  • Higher‑watt chargers help especially when the laptop is in use; ultra‑low‑power phone chargers can cause oscillating charge/discharge cycles.

Safety and quality of cheap chargers

  • Strong caution against very cheap or no‑name chargers:
    • Risks include inadequate creepage/clearance, wrong component failure modes, electric shock, fire, and device damage.
    • Multiple anecdotes of exploding chargers, strong tingling, interference with other equipment, and unsafe designs.
  • Emphasis on buying from reputable brands and trustworthy retailers; enforcement of safety standards is seen as weak.

Reliability of Apple chargers and cables

  • The article’s conclusion that Apple chargers are well‑engineered but not perfectly reliable is echoed.
  • Internal failures and burn marks are mentioned, but some say the “bricks” themselves have generally been reliable compared to the historically fragile Apple cables.
  • Apple has moved from soft plastic to braided cables in response to past fraying issues.

Ground pin and modular “duckhead” design

  • Question about why Apple includes a ground pin on the brick but often ships only a 2‑prong adapter in the US.
  • Explanations:
    • Same brick is used in countries that require grounding.
    • Users can attach a grounded extension cable or alternate plug module for travel or to reduce tingling.

Repair vs replace philosophy

  • One commenter contrasts beautifully engineered but hard‑to‑repair sealed devices (like modern chargers) with cruder, easily repairable hardware.
  • View expressed that reliability can’t be fully known until long‑term use, and that the broader trend is toward highly integrated, “lifetime” parts that are uneconomical to repair.
  • Others note they do repair some power supplies and electronics, but acknowledge that modern designs and materials increasingly discourage repair.

Miscellaneous technical asides

  • Comment noting that even chargers and higher‑power USB‑C cables embed microcontrollers/e‑markers rivaling early computers in capability.
  • Brief side note that better‑managed/cleaner power (e.g., PDUs, surge protection) may correlate with longer device life, though continuous “clean” power effects on batteries are questioned.