Galaxy Watch 7 and Watch Ultra need bundled charger for fastest charging

But that's not all. The redesigned sensor also makes it impossible for the Galaxy Watch 7 and Galaxy Watch Ultra to charge at the maximum speed with chargers that came with older Galaxy smartwatches.

Older chargers are supported, but work slower

You need to use the charger bundled with the Watch 7 and Watch Ultra for optimal charging speeds. As Samsung notes, the change in the sensor's design and the shape of the back glass “increased the distance between the internal wireless charging coil of your Watch and the wireless charger, which may result in slower charging and higher heat generation.”

In simpler terms, the upgraded health sensor—officially called the BioActive sensor—and the glass that covers it have a curvier shape, which essentially means the back is not as flat as it was on previous models. So, compared to chargers for previous models, Samsung redesigned the Watch 7 and Watch Ultra charger to be more curvy for better contact with the back of the watch.

Some Samsung fans may feel disappointed by the charging-related limitations on the Watch 7 and Watch Ultra. However, as we discovered when reviewing the latter, the improved health and fitness tracking is well worth the compromise. You can read our detailed Galaxy Watch Ultra review here.