The older AW charging cables will not fast charge, only the one that comes with the watch. It wont fast charge older AW. Oh an you should get the 20W brick that apple sells
www.theverge.com
If you want to use the Apple Watch Series 7’s new fast charging, make sure to use the cable in the box
Use the right charger.
️ charger will hurt the series 7 battery? I know it won’t fast charge, but wondered if it would be bad for it.