smelly catalytic converter?

Maybe the voltage regulator is stuck check your charging voltage , engine running. No accessories on . Should show no more than 14.7- 14.8 volts . Any higher and you have an overcharging issue. Be careful . An overcharging battery is giving off a buttload of hydrogen , any sparks could ignite it and result in a battery explosion. Hose off the battery with a gallon of water and fan the area surrounding it to dissipate any dangerous gasses. Looks and sounds silly , but believe me you don't want that to happen.