My V5 has gotten the low battery symbol a few times but I've never heard it beeping, nor have the other connections I have consistently run (V3 and V4). However, I never left them on a low battery for long as I would replace the battery. I hear the V2 and V3 have a special "heartbeat" feature where they make soft, consistent beeps when they are to imitate a heartbeat. One night this got to me - and it usually doesn't - so I turned off the sound and that did something. I just tested it and the heartbeat with the sound off is softer than when the sound is on, but it is still there. Chances are turning the sound off when it makes the low battery beep will do something but not completely remove it.
Nazotchi25 gave you a good suggestion to remove the battery, and this will also not cause any problems as all connection models have a download feature to start again from past data.