Galaxy Watch 9 and Galaxy Watch Ultra 2 owners are experiencing charging times ranging from two to four hours, significantly missing Samsung’s advertised windows of 80 to 90 minutes, according to reports collected by Android Authority. Technical analysis points toward aggressive thermal throttling and possible charger compatibility issues as the primary drivers behind the unexpected delays.
Real-World Charging Speeds vs. Manufacturer Claims
Samsung officially rates the 40mm Galaxy Watch 9 at 80 minutes for a complete 0% to 100% charge. Larger variants, including the 44mm Galaxy Watch 9 and the Galaxy Watch Ultra 2, carry an official rating of 90 minutes. However, early adopters on Reddit and official forums report starkly different outcomes under normal room conditions. According to Android Authority, a 40mm Watch 9 user documented a full cycle taking well over two hours, while a Watch Ultra 2 owner logged a four-hour wait.
Contrasting testing reveals additional variance depending on power delivery equipment. As reported by SammyGuru, PhoneArena testing utilizing Samsung’s official 25W adapter required more than four hours to fill a Galaxy Watch Ultra 2, reaching only 18% in 30 minutes and 30% after a full hour. Conversely, testing by SammyGuru using a 45W USB-C charging brick completed a 1% to 100% charge in approximately 1 hour and 34 minutes. Jeff Springer of SammyGuru noted that the original Galaxy Watch Ultra models required roughly 1 hour and 48 minutes on the same 45W brick, despite featuring a smaller 590mAh battery compared to the Ultra 2’s 800mAh capacity.
Pro Tip: Charging results can vary dramatically based on the power brick used. Outlet testing indicates that pairing the device with a higher-capacity 45W USB-C brick yields significantly faster results than bundled or lower-wattage official adapters, according to SammyGuru’s hardware evaluations.
Thermal Throttling and Power Management Complications
Behind the sluggish replenishment times, thermal management appears to heavily restrict power delivery. Android Authority reports that the wearables repeatedly throttle charging speeds—dropping power from 5.5W down to 3.5W or lower—as internal temperatures rise during active sessions. To counteract this heat buildup, some users have resorted to external cooling hacks to maintain faster power intake.
Beyond heat regulation, hardware handshake complications add to the friction. Reports on the US Samsung Community forum cited by Android Authority indicate that backwards compatibility with older Galaxy Watch 8 chargers and third-party docks is frequently broken. Affected devices routinely display “slow charging” alerts or reject power sources entirely. Interestingly, some users discovered that plugging into an older Galaxy Watch 6 puck delivered faster results than the included fast-charging cable, pointing toward firmware communication errors rather than pure hardware limitations.
Did You Know? The Galaxy Watch Ultra 2 features an 800mAh battery—a roughly 35% capacity increase over the 590mAh cell found in the original Galaxy Watch Ultra—yet properly powered units can complete a full charge in roughly 94 minutes, according to SammyGuru testing.
Frequently Asked Questions
How long should the Galaxy Watch 9 and Watch Ultra 2 take to charge?
Samsung officially rates the 40mm Watch 9 at 80 minutes and the larger 44mm Watch 9 and Watch Ultra 2 at 90 minutes. However, real-world user reports compiled by Android Authority show actual times stretching from two to four hours depending on hardware and thermal conditions.
Does the choice of wall adapter affect charging speed?
Yes. Testing highlighted by SammyGuru shows that using a 45W USB-C charging brick charges the Watch Ultra 2 in about 1 hour and 34 minutes, whereas using Samsung’s official 25W adapter resulted in charging times exceeding four hours in comparative tests.
What causes the slow charging speeds on newer Samsung watches?
According to Android Authority, primary factors include aggressive thermal throttling—where the watch drops power from 5.5W to 3.5W or lower as heat builds—alongside firmware handshake issues affecting compatibility with older chargers and third-party docks.
Have you experienced slow charging times on your Samsung wearable, or did a different power brick solve the issue for you? Share your experience in the comments below, and explore our archives for more hardware analysis and device guides.
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