Weird smell when using ehu

Hi, has anyone ever smelt a gas like/ propane smell when using ehu.
I think my leisure battery isnt holding charge, an i checked its voltage,  reading 11.12 volts after a full nights charging, But reads 12.14 volts on charge.
Also the * indicator * button hasno  green/grey/blank symbol.

The smell will be coming from the battery being charged.  It sound like your battery needs replacing sharpish.

Ok, thanks
Will change it just to be sure, after all ir is 8+ years old and i dont have history of its usage( second hand campervan)