Apple in a support document detailing best practices for its MagSafe Duo charger, said that users will not be able to simultaneously charge an iPhone 12 and Apple Watch with the company’s 29W power adapter.
MagSafe is a new feature on all iPhone 12 models that allows for magnetic accessories to be attached to the back of the devices, including Apple’s MagSafe Charger for more precise wireless charging.
According to the support document, Apple’s older 29W USB-C power adapter is not compatible with the MagSafe Duo, presumably because that adapter does not support the necessary 5V/3A or 9V/1.67A power ratings.
Due to this when the MagSafe Duo is connected to the 29W adapter, it can only charge either an iPhone or Apple Watch, rather than both devices simultaneously.
Earlier, Apple indicated that its new MagSafe Charger will be limited to 12W peak power delivery when used with iPhone 12 mini, compared to up to 15W for other iPhone 12 models.
When Lightning accessories such as EarPods are connected to any iPhone 12 model, the MagSafe Charger is limited to 7.5W charging to comply with regulatory standards.
Apple said that one should connect the MagSafe charger with the power source and then put the iPhone 12 on it.
This lets the charger verify that it is safe to deliver maximum power.