high pitched sound when charging car battery

[yuriythebest]

Hello! I have a 12v CA lead acid battery, when charging it using a smart charger, at the point where the indicator says it’s close to full, there is a faint high-pitched electronic sound ( like from voltage) - is this bad for the battery and should I stop charging at this point? After stopping charging, the battery showed 12.7v for a bit, then went to 12.6 - thanks in advance!

 

[kindai]

It was likely the charger just providing a low level voltage and that just happens at a frequency you can hear.

 

[Dis86]

Pretty normal

 

[theone8181]

I thought that was the desulfanation part.

 

[Rich1988]

Transformer whine, totally normal for chargers