Hissing battery

[Jepri]

I just fired up my laptop and heard an odd hissing noise.  After 
checking the exhaust fan, drive etc, I realised that the sound was 
coming from the battery.  Putting my ear against it confirmed it.  I 
then realised I had my face pressed against a hissing battery...

The laptop appears to be overcharging the NiMH battery, and I guess 
that means it was venting hydrogen.  Scary.

I'm not sure there was a point to this post, it's just weird, and a 
little scary.