is there a way to stop the beeping the phone makes when fully charged?

It shouldn't ever beep. I have owned every iPhone since the original and none of them have ever beeped when fully charged. You are probably hearing something else and confusing it for this.

Ditto. None of mine have ever done that.

They are not designed to do this. Not sure what's going on with yours.

I've never heard of that. Maybe it's some battery app you installed? Is your iPhone jailbroken?

Standard troubleshooting...

• Try a reset by pressing the home and sleep buttons until you see the Apple logo, ignoring the slider. Takes about 5-15 secs of button holding and you won't lose any data or settings.
• If still a problem restore from your backup.
• If still a problem restore as new, i.e. without your backup.
• If still a problem, it's likely a hardware issue.

Sounds like your USB charger is defective & is cycling on/off after your battery is fully charged. I've seen this before. Make an appointment at an Apple store.

Are you using a 3rd party charger?

My week old iPhone 5 has started beeping constantly when it reaches fully charged. This has been happening for the last 2 days. It didn't happen the first few days, just yesterday & today.

I don't know hy is this happening. How can I make it stop.