Explainers
How cables, speeds, and Power Delivery actually work.
How I Test Chargers: The Watt Check Methodology
The complete test rig and methodology behind the Watt Check charger series - what's measured, what's controlled for, and why a USB 2.0 cable is the right call for power testing.
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USB-C Charging Speed and Data Speed Are Independent - Here's Why That Matters
Your 240W charging cable might only do USB 2.0 data. Your speedy USB 3.2 cable might cap at 60W charging. These specs are independent - here's why, and what to look for.
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Why Is My Device Connecting at USB 2.0 Speed? How to Diagnose a Slow USB-C Connection
A USB 3.x device stuck at 480 Mbps is almost always caused by a USB 2.0 cable. Here's how to confirm it and what to replace.
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Why Only Apple Chargers Show Their Name on Mac
Apple's chargers are the only USB-C chargers that fully identify themselves to macOS - name, model, firmware, serial. Here's why third-party chargers appear as generic 'Power Supply' and what the app shows in that case.
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Setapp vs Mac App Store: Where to get USB Connection Information
We're bringing USB Connection Information to Setapp's new Standalone store. Here is a breakdown of the differences between purchasing through the Mac App Store versus Setapp.
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Can You Charge a MacBook With an Old Apple iPad Charger? (Measured)
I tested an Apple 5W, 10W, and 12W USB-A brick against an M1 MacBook Air through a USB-C adapter. Spoiler: macOS falls back to USB BC 1.2 and caps at 7.5W regardless of the brick's rating.
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Why Are Some USB-C Cables Limited to 100W? EPR and USB PD 3.1 Explained
100W used to be the top of USB-C charging. USB PD 3.1 pushed the ceiling to 240W - but only with new EPR-rated cables. Here's why, and how to tell which ceiling your cable hits.
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USB-C Cables With and Without eMarker Chips: What's the Difference?
The chip inside a USB-C cable decides whether you get 60W or 240W charging, and USB 2.0 or USB 4 data. Here's how eMarkers work and how to tell which kind you have.
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Is My iPhone Connected via USB 2.0 or USB 3? How to Check
Your iPhone 15 Pro or 16 Pro supports 10 Gbps transfers - but the cable in the box is USB 2.0. Here's how to tell which speed you're actually getting, and the ~20× real-world difference.
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Thunderbolt 4 vs. USB4: Identifying Your Connection Type
Same plug, same marketing buzzwords - but Thunderbolt 4 and USB4 are not the same. Here's how to identify what you actually have.
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Why is my Mac Charging Slowly? Monitoring USB-C Power Delivery (PD)
Mac charging slowly? It's probably a Power Delivery negotiation mismatch. Here's how PD works and how to see the profiles your charger actually advertises.
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How to Check USB-C Cable Speed & Data Transfer Rate
Identical-looking USB-C cables can run at 480 Mbps or 10 Gbps - here's how to verify the real negotiated speed on Mac and Windows.
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Tested
Real chargers measured on a MacBook Air. Advertised profiles, negotiated contract, live draw.
Apple 96W USB-C Power Adapter on a MacBook Air: Measured
Negotiates 94 W at 4.7 A - the largest contract in the series. Swap to a non-e-marked cable and the same adapter drops to 60 W, with the app naming exactly what's missing.
See the measurements →Apple 40W Dynamic Power Adapter (60W Max) on a MacBook Air: Measured
One charger with two ratings. It offers 40 W sustained and a 60 W peak marked DPS, and the Mac negotiates the peak - drawing 56.1 W live.
See the measurements →Dell WD22TB4 Thunderbolt Dock on a MacBook Air: Measured
Negotiates 90 W at 4.5 A while simultaneously carrying Thunderbolt 4 at 40 Gbps and a Realtek gigabit LAN adapter. One cable doing what a charger cannot.
See the measurements →Anker 20,000mAh Power Bank on a MacBook Air: Measured
Delivers 62.3 W to a laptop from a battery, with five fixed profiles and PPS up to 5 A. It also identifies itself as Chipsea Technologies - the PD controller chipmaker, not Anker.
See the measurements →UGREEN 30W Charger on a MacBook Air: Measured
Delivers its full 30 W and offers that rating three times over - at 12 V, 15 V and 20 V. The most flexible fixed-profile menu in the series.
See the measurements →AUKEY 20W Charger on a MacBook Air: Measured
Delivers its full 20 W, but over a 12 V rail rather than the usual 9 V - and offers that rating on both. Includes PPS up to 2 A.
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