Hi John
As the charging indicator returns to red upon removal from the charger, check that:
- All plastic wrap has been removed from both ends and both sides of the charging cable (check closely on the head of the charger).

- The back of your watch and the head of the charging cable are clean and dry (clean them with a lint-free cloth and retry).
- The charging head is directly aligned with the back of the watch, with the concave / curved side touching it fully:
- Some watch docks, stands, cases or protectors might hinder this.
- You are using only the genuine Apple Magnetic Charging Cable or an Apple certified magnetic charging module.
- If you are charging your watch by plugging into mains power, try using different adapters from the following:
- The genuine Apple USB Power Adapter that was supplied with the watch, or;
- A genuine Apple 5W (iPhone) or 12W (iPad) USB Power Adapter, or;
- Apple-certified (MFi) third-party 5W power adapter.
- If charging via a USB port, ensure that you use a USB 2.0 or 3.0 port, the computer remains turned on and awake and the cable is plugged directly into the computer (not into, for example, an external keyboard).
Under normal operation, charging should only take up to around 2.5 hours for a full charge.
More information:
Check your battery and charge your Apple Watch - Apple Support
If the issue persists after following these steps, contact Apple Support (mail-in service may be available) or make a Genius Bar reservation with a view to having your watch and/or power accessories checked under warranty:
https://www.apple.com/support/watch/contact/
By the way: although your query is on a related subject, it is different to the original question here, which has already been answered. A different question should be asked in a new thread. If others later have the same query, this also makes it easier for them to find - hopefully along with an answer.
More information: Find answers and ask new questions