16in M1 Macbook Pro keeps dinging after its fully charged

It sure sounds like a hardware issue of some sort. Try using a USB-C cable to charge the laptop instead. Do you still have this issue? This can be the cheap "fix", but the Magsafe charging issue could get worse & even affect USB-C charging. If you just purchased this laptop, then you may want to return it for a full refund. It sounds like you most likely inherited the previous owner's problems.

Did you perform a clean install of macOS when you acquired this laptop even if the previous owner had done so? If not, then see the following Apple article on what the previous owner should have done.....being the new owner, you can only start at the "Erase" step.

Jd6885 wrote:

I got a used 16 inch M1 Macbook Pro. When it's fully charged using the magsafe charger, it repeatedly makes the dinging sound you hear when you first plug in your macbook. It does this every couple of minutes or so and doesn't stop unless you take the magsafe charger out. There's no issue while it's charging. It's only when the macbook is fully charged does it keep making this sound. It's as if the macbook keeps trying to charge past 100%. I say this because right before it makes the noise, the charger light turns from green to orange like it would when it's not fully charged

verify your software is up to date—

The current stable release of Tahoe including bug fixes, security updates is macOS 26.1

Keep your Mac up to date - Apple Support

Keep your Mac up to date - Apple Support

you can unplug the power adapter from all cables and wall power for 60 secs to reset it— and plug it all back in to test.

ref: If your MagSafe cable or power adapter isn't working

If your MagSafe cable or power adapter isn't working - Apple Support

no resolve—

A SafeBoot Start up your Mac in safe mode - Apple Support will sort many anomalies

Login and test. Reboot as normal and test. Caches get rebuilt automatically.

Grant Bennet-Alder wrote:

this is likely the article:

What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

Thanks, that is the one since Apple has recently made major changes to many of their articles, this is the only one with simple clear steps listed. I guess I got distracted when writing my response (I may have thought this was another similar thread where I was assisting for the same thing).

Greatly appreciate the assist.

this is likely the article:

What to do before you sell, give away, trade in, or recycle your Mac - Apple Support