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If a MagSafe charger can charge at 15W using a 20W Apple charger, that's a 75 percent charge efficiency. The charger itself is about 80 percent efficient conver
by selectodude 6y ago
If a MagSafe charger can charge at 15W using a 20W Apple charger, that's a 75 percent charge efficiency. The charger itself is about 80 percent efficient converting from the wall, so the whole thing is about 60 percent efficient. An iPhone 12 has a 15 wh battery, so you need about 25 wh to charge the battery fully vs 19 wh. So the losses for 17,000 full charges using MagSafe over a regular cable would equal the charge in a 100kwh Tesla Model S.
ETA: the total charging loss from ten million iPhones charging 0-100 percent via MagSafe every day for a year would be 21,505 teslas.
- jiofih 6y agoYour numbers are a bit high, wired chargers have become more efficient and barely waste any energy, see here: (14wh spent to charge a 13wh battery) https://www.researchgate.net/publication/309917872_Improving_wireless_charging_energy_efficiency_of_mobile_phones_Analysis_of_key_practices https://www.researchgate.net/publication/309917872_Improving... The last bit is also wrong, 6wh * 10M = 600 Teslas. You can also read as “600 Teslas can provide phone charging for ten million people for an entire year”, take it as you wish... Your fridge can easily use 100kWh a month. You’ll save far more energy by closing the door a couple seconds early every time you open it. Phone charging is a drop in the bucket.