By that we mean that you can charge your Series 7 watch on the MagSafe Duo, but if you do, then don’t expect fast charging to work. According to Apple’s support document, it says, “MagSafe Duo Charger doesn’t support fast charging with Apple Watch Series 7. To fast charge your Apple Watch Series 7, use the Apple USB-C Magnetic Fast Charging Cable.”
It was recently discovered that Apple had updated the Apple Watch Series 7’s charging puck where not only is it made out of aluminum, but it is also USB-C instead of USB-A. This means that it will work with Apple’s 20W charging brick that will support fast charging. This is a bit of a bummer for those who bought the MagSafe Duo, more so when you consider that the accessory costs $129.
We’re not sure why Apple did not plan ahead for this or if this could be a sign that they might update the MagSafe Duo for fast charging compatibility, but either way if you care about fast charging, then this is not the accessory for you.