Beeping battery
 

I installed a new battery in my 2000 Intruder 800 early Fall 2019 and always keep the bike hooked up to the battery tender when not in use. This past weekend I went into my bike shed and heard an intermittent, faint beeping sound. A quick sound check located it near the battery area. The occasional (every 10 seconds or so) beeping stopped when I unplugged the battery tender and started up again when I plugged it back in. I've never noticed this before. I decided to leave the tender unplugged, but don't like the idea of doing that all winter. Any idea what this could be?

Haven't received a reply from anyone yet, so I decided to take another look at things... After being off the battery tender for a week, the battery's voltage is holding steady at 12.6. With the tender hooked up it is 14.4. There are no aftermarket devices installed, the tenders are about four years old and the battery is new as of a few months ago.The same high pitch noise was observed coming from the battery "area," stronger from the left side of the bike, when hooked up to the tender. I tried making audio and video/audio recordings, but the noise is so faint I don't think you'll be able to hear it. When I disconnect the battery tender, the noise stops, and when I reconnect it, it starts again.... a soft, faint, high pitch hum or beep that lasts several seconds, stops for a second and starts up again.

I switched the tender on my bike with the one on my son's bike. My tender on his bike made no noise. His tender on my bike didn't hum/beep, but instead made a faint bubbling sound (like boiling, but no heat to the touch, so I assume it was electrolisis or something like that in the battery).

Hopefully you'll be able to hear these clips with the volume turned up:

These are with my tender on the bike:
1-video and audio with tender one
2-audio with tender oneAnd this one is when I switched tenders and put my son's on my bike:
3-audio with tender twoIn case the links above are not clickable, you can copy and paste these:

1: https://drive.google.com/file/d/1y2n...FhV4dkwFf/view

2: https://drive.google.com/file/d/1PpH...ew?usp=sharing

3:https://drive.google.com/file/d/12gq...ew?usp=sharing

Really curious to hear any guesses about what might be happening.