Why is there no sound when the smart charger of electric vehicle is charging?

I have answered this question countless times. Your electric car is not fully charged, but the electrolyte in the battery has evaporated. If you want to add it, do you feel your battery case burning? It should be hot! You can't ride the original distance now because the battery will be scrapped if the electrolyte is not replenished in time. Open the battery box and have a look, the battery may bulge! Suggestions.