Why this answer matters
A 45W adapter alone does not prove the phone is receiving 45W at every moment. USB-C charging is negotiated and battery management reduces power when conditions require it.
3 requirements3 verification steps2 primary sources
Requirements
What has to be true
- A compatible 45W USB-C power adapter.
- A cable suitable for the required current/power path.
- Charging conditions that allow the phone to use its faster charging profile.
Verify it yourself
Use this test sequence
Change one variable at a time so you know which requirement made the difference.
- 1
Confirm the exact phone model is S25 Ultra rather than base S25.
- 2
Test with a known-good compatible cable and charger before treating the USB-C port as faulty.
- 3
Compare charge behavior at low battery percentage and with the screen/device workload reduced.
Limits
What this answer does not prove
- The maximum supported charging class is not a constant real-time draw.
- Browser tools cannot read Samsung's protected charging telemetry directly.
Relevant DeviceOK checks
Test the part you can observe
Charger Wattage MatchCompare a device's entered power requirement with a charger's rated wattage while keeping USB-PD/PPS and voltage-profile limits explicit.
→USB-C Cable Power Rating CheckCompare an entered cable wattage rating with the power you want to carry, while keeping protocol/e-marker limits explicit.
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