A DJI Drone Remote as a Mac Charger: The First One That Failed
The USB-A port on a DJI drone remote controller, measured on a MacBook Air M5: 2.5 W at 500 mA. The first source in this series that could not charge the Mac at all.
The USB-A port on a DJI drone remote controller, tested against a MacBook Air M5 with a low battery, per the methodology.
Every source measured in this series so far has done something. Even the weakest of them slowed the battery’s decline. This is the first one that did not.
The numbers
| Rated | 3 W |
| Negotiated | ~3 W (5 V up to 0.5 A) |
| Live draw | 2.5 W (5 V at 0.5 A) |
| Protocol | USB BC 1.2, at its 500 mA tier |
Profile menu: one entry. There is nothing to negotiate.
500 milliamps is the tell
Look at the current: exactly 0.5 A. That number is not a coincidence, and it is not the remote being stingy.
macOS reports the same protocol here as on every other USB-A source in this series — USB Battery Charging 1.2 — which is the detail worth understanding, because BC 1.2 is not one thing. It defines three kinds of port:
| Port type | Allowance |
|---|---|
| Standard Downstream Port (SDP) | 500 mA - an ordinary data port |
| Charging Downstream Port (CDP) | 1.5 A, data as well |
| Dedicated Charging Port (DCP) | 1.5 A, power only |
Every other USB-A source measured here presents as a charging port and lands at 1.5 A. This remote presents as a Standard Downstream Port — the plain data socket on the side of a device — and 500 mA at 5 V is its entire allowance. That is 2.5 W, and 2.5 W is exactly what arrived.
So “it speaks BC 1.2” and “it can charge things” are not the same statement, and this is the device that makes the difference visible. The port was built to move data to and from a drone. It charges nothing because it never claimed it could.
Why it charges nothing
An M5 MacBook Air idling with the display on draws several times 2.5 W. So the arithmetic is simply unfavourable: power in is smaller than power out, and the battery percentage goes down while the cable is plugged in.
macOS still reports a power source attached, which is the confusing part — the menu bar shows something connected, and the battery keeps falling anyway. There is no fault and no warning, because nothing is broken. The remote is delivering exactly what it promised.
This is the floor of the series, below even the USB port on a 2004 AirPort Express, which manages 3.3 W - though that one gets there by advertising 7.5 W and failing to hold it, where this remote simply never claimed more than it gives.
The general rule, again
A USB-A port on a device that is not a charger is a data port that happens to supply power. Expect 2.5 W from it, and 7.5 W only if the device deliberately advertises itself as a charging port.
The list of things this covers is long and includes most of the ports people try in an emergency: a monitor, a keyboard hub, a router, an airline seat, a hotel nightstand, a drone remote. None of them will charge a laptop, and none of them are defective for failing to.
If a port cannot tell you its wattage, assume 5 W. You will never be disappointed, and occasionally you will be pleasantly surprised.
The unit
For reference, this is the DJI remote controller tested. It is a drone accessory, not a charger, and it is listed here only so you can identify the exact unit.
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Related
- The USB port on a 2004 AirPort Express - the other non-charger port
- The USB port on a desk power strip - what a real 7.5 W port looks like
- How many watts does your Mac actually need?
- Testing methodology · Gear list