HP 45W USB-C Charger on a MacBook Air: Measured
HP's 45W USB-C charger measured on a MacBook Air: 41.8 W delivered. Every profile it offers sits at exactly 3 A, and it stops at 15 V - so it hits 45 W without ever needing a 5A cable.
HP’s 45W USB-C power adapter, tested against a MacBook Air with a low battery, per the methodology. It turned out to be one of the more unusual profile ladders in the series.
The numbers
| Rated | 45 W |
| Negotiated | 45 W (15 V up to 3 A) |
| Live draw | 41.8 W (14.8 V at 2.82 A) |
| Protocol | USB PD 3.0 |
| Identifies as | HP |
Profile menu:
| Profile | Rail |
|---|---|
| 15 W | 5 V up to 3 A |
| 27 W | 9 V up to 3 A |
| 36 W | 12 V up to 3 A |
| 45 W | 15 V up to 3 A (active) |
No PPS.
Every rung is exactly 3 amps
Look down the current column. 3 A, 3 A, 3 A, 3 A. Every profile this charger offers pushes the full 3 amps, and the wattage climbs purely by raising the voltage.
That is not how most chargers are built. A typical ladder mixes currents - 2.22 A here, 1.67 A there - because the designer is fitting each rung under a fixed power budget. HP instead pinned the current at the maximum an ordinary cable can carry and stepped the voltage: 5, 9, 12, 15.
The practical payoff is the cable. 3 A is the limit of a USB-C cable with no e-marker chip, which is to say almost every cable you own. Because this adapter never asks for more than 3 A on any rung, it reaches its full 45 W through a plain cable. Chargers that climb past 3 A need a 5A e-marked cable to hit their rating, and quietly drop to 60 W without one. This one has no such trapdoor.
No 20 V step
The other half of the story is what is missing. The ladder stops at 15 V. There is no 20 V rail, which is the rung laptops normally settle on.
That caps it at 45 W by design - 15 V times 3 A. For a MacBook Air, 45 W is real charging, comfortably more than half of what the machine will take. For a larger laptop it is a top-up rather than a fast charge. The absence of a 20 V rail is also why this charger can keep the “3 A everywhere” trick: to go past 45 W at 3 A, it would have needed the 20 V step.
It names itself
The app reports this one as HP. That puts it in the minority of third-party chargers that answer the Mac’s standard PD Discover Identity request with a real brand rather than staying anonymous. Plenty of chargers in this series show up as nothing more than “PD Charger”.