The Apple Charging Situation — Built by Grumbles

The Charging Curve

Three phases. One that matters.

0 → 50%

Full-speed constant current. Your charger matters here. Only here.

50 → 80%

Current tapers. Better charger still helps. Less than you'd think.

80 → 100%

Trickle charge. 140W and 20W finish the same. Chemistry doesn't negotiate.

Stock

The charger in the box (iPads, Macs), or a 20W USB-C (iPhones — no charger included since 2020).

Optimal

The fastest charger the device can actually use. More watts than this won't help -- the device caps out.

iPhones

No charger in the box since 2020

Device<br>Max W<br>0→50%<br>20W<br>0→50%<br>Optimal<br>Faster

iPhone 17 Pro Max (19.6 Wh)<br>40W<br>~38m<br>~20m<br>47%

iPhone 17 Pro (16.0 Wh)<br>40W<br>~31m<br>~20m<br>35%

iPhone 17 (14.0 Wh)<br>~27W<br>~28m<br>~20m<br>29%

iPhone 17e (15.4 Wh)<br>20W<br>~30m<br>~30m

iPhone 16 Pro Max (18.0 Wh)<br>30W<br>~30m<br>~26m<br>13%

iPhone 16 Plus (18.0 Wh)<br>~27W<br>~30m<br>~27m<br>10%

iPhone 16 (13.7 Wh)<br>~23W<br>~30m<br>~27m<br>10%

iPhone 15 Pro Max (17.3 Wh)<br>27W<br>~30m<br>~27m<br>10%

iPhone Air (12.3 Wh)<br>~20W<br>~30m<br>~30m

The Air and 17e both cap at 20W — a 140W charger finishes at the same speed as a basic 20W. Save the good charger for a device that can use it.

iPads

Where the right charger matters most.

Device<br>Ships<br>With<br>Max W<br>0→50%<br>Stock<br>0→50%<br>Optimal<br>Faster

iPad Pro 13" M4 (39.0 Wh)<br>20W<br>~35W<br>~1h 30m<br>~45m<br>50%

iPad Pro 11" M4 (31.3 Wh)<br>20W<br>~35W<br>~1h 15m<br>~37m<br>51%

iPad Air 13" M4 (36.6 Wh)<br>20W<br>~31W<br>~1h 25m<br>~55m<br>35%

iPad Air 11" M4 (28.9 Wh)<br>20W<br>~31W<br>~1h 10m<br>~45m<br>36%

iPad mini 7 (19.3 Wh)<br>20W<br>~20W<br>~45m<br>~45m

The Pro costs $1,299. Apple included a half-speed charger. I have feelings about this.

MacBooks

The Airs ship better. The Neo ships like an iPad.

Device<br>Ships<br>With<br>Max W<br>0→50%<br>Stock<br>0→50%<br>Optimal<br>Faster

MBP 16" (Pro/Max) (100 Wh)<br>140W<br>140W<br>~26m<br>~26m

MBP 14" (all configs) (72.4 Wh)<br>70–96W<br>96W<br>~30–35m<br>~30m<br>0–14%

Air 15" M5 (66.5 Wh)<br>40W<br>~70W<br>~52m<br>~30m<br>42%

Air 13" M5 (53.8 Wh)<br>40W<br>~70W<br>~45m<br>~26m<br>42%

MacBook Neo (36.5 Wh)<br>20W<br>30W<br>~1h 25m<br>~55m<br>35%

Airs fast-charge at 70W but now ship with 40W — better than the old 30–35W, but still almost half-speed. The Neo ships with 20W on a 30W device — the biggest gap in the laptop lineup. The base M5 and 16-core Pro ship with 70W — below their 96W fast-charge threshold. As of macOS Tahoe 26.4, Apple will literally tell you — an orange "Slow Charger" label appears in the battery menu when your adapter can't keep up.

Wearables

The cable matters more than the charger.

Apple Watch Series 11, Ultra 2 · Fast-charges to 80% in 30–45 min — but only with the Apple USB-C Magnetic Fast Charging Cable and any USB-PD adapter (5W+). Wrong cable? Roughly twice as slow.

AirPods Pro 3, 4, Max 2 (USB-C) · 3–5W. Any charger. These actually don't care.

The Apple Charging Situation

Battery Health

Everyone worries about the wrong thing.

Heat

The #1 killer. At 45°C (113°F), lifespan is halved vs. 20°C (68°F). A phone on a hot dashboard with a 5W charger degrades faster than fast-charging indoors at room temperature.

Time at 100%

High voltage stresses the cell. Optimized Battery Charging exists specifically to minimize this — holding at 80% overnight instead of sitting at 100% for hours.

Charge Depth

Shallow cycles (30–80%) are gentler than deep ones (0–100%). Apple already accounts for this in their specs. Don't obsess.

Charge Speed

Least important for Apple devices. The charge curve tapers so aggressively that "fast charging" only hits peak wattage for ~15 minutes, then throttles back on its own.

Ranked by actual impact. Most people worry about #4. They should worry about #1.

The 80% Question

Not a myth. Apple read the same papers I did.

If charging stops at<br>Battery lasts for<br>vs. 100%

100%<br>300–500 cycles<br>baseline

~90%<br>600–1,000 cycles<br>~2×

~80%<br>1,200–2,000 cycles<br>~4×

~70%<br>2,400–4,000 cycles<br>~8×

"This is the math behind Optimized Battery Charging. Every 10% Apple holds back roughly doubles battery lifespan."

Optimized Battery Charging

Learns your routine. If you unplug at 7 AM, it holds at 80% overnight and tops off at ~6:30 AM. Cuts time at max voltage from 8 hours to ~90 minutes.

Charge Limit (iOS 17+ / macOS Sequoia+)

Manual cap between 80–100% in 5% steps. Built for the "MacBook lives on the desk" crowd. If you keep devices 3+ years, this one's for you.

Thermal Throttling

Monitors temperature in real time. Reduces power when hot, pauses entirely if too hot. That steep wattage drop in the charge curve? That's this kicking in.

Cold Charging Block

Below 0°C (32°F), charging is blocked entirely — cold causes permanent damage. Between 0–10°C (32–50°F), charge speed is reduced automatically.

Slow Charger Warning (macOS Tahoe 26.4+)

Orange "Slow Charger" label in the battery menu and Battery settings when your adapter isn't delivering full power. Apple's own admission that the charger in the box might not be enough.

Above 80%, the battery is working its hardest — voltage spikes, chemistry gets stressed, wear accelerates. Apple knows. That's why...