Strange LA Charger Noise?

[Scooterman]

It's quite faint so you may have to turn up the volume. For ages I thought the noise was coming from an outside car alarm in the distance. So far I've only notice it when the charger is in it's float stage. It's not the fan because that is really noisy and shuts off after a few minutes. I can only describe the noise as being 'electronic'?

https://drive.google.com/file/d/1g6M-f_ ... sp=sharing

[Scooterman]

MP3 version

https://drive.google.com/file/d/1L-rz_D ... sp=sharing

[Burgerman]

Its something to do with the way its doing float... What you are hearing is the power on/off pulsewidth possibly. Its a square wave at some usually high frequency. Or its about to explode!

[Scooterman]

Or its about to explode!

Ooh!