Old Apple Watch Chargers Can’t Fast Charge the New Series 7

If you’ve got a few old Apple Watch chargers lying around and are thinking of getting in line for the new Series 7—which is available for order starting today—you better mark them with a tag or something before you bring your new watch home.

There is a reason for this, dear readers. See, one of the Series 7’s improvements this year is its faster charging time. According to Apple, the Series 7 can be charged 33% faster when compared to previous models, reaching an 80% charge in about 45 minutes. For people like me, who keep their Apple Watch around the house and only use it to go to the gym and burn baby burn, this is good news. There’s nothing worse than realizing your watch has low battery when you’re getting ready to head out.

However, fast charging will only be available for people who use Apple’s new USB-C magnetic fast charger with the Series 7, which is equipped with a new charging architecture. Don’t worry, this cable is included in the box, but since it looks just like the older cables, it’s important to be able to tell them apart to get the charging speeds you’re expecting.

That doesn’t mean that the Series 7 won’t charge if connected to an older Apple Watch charger. It just means that it won’t be able to use fast charging. Likewise, you can use the new USB fast charging cable with old Apple Watch models, but they’ll charge at their regular speeds. For comparison’s sake, the Series 6 can be fully charged in an hour and a half.

Apple doesn’t want you to get confused, so it’s decided to no longer sell the old watch chargers on its website. It now only sells fast chargers for $29. However, as pointed out by the Verge, old Apple Watch chargers are still sold third party sites like Amazon. It’s no cause for panic, of course, but it’s good to know that you need a new fast charger to take advantage of all the Series 7’s offerings and that your old chargers won’t work as expected.

The Apple Watch Series 7 starts at $399 and will be available in stores beginning on Oct. 15. If you’re wondering whether you should upgrade, check out our handy guide.