If you have the battery charger set at a higher amp rating and not just trickle charge the battery should charge fully within 2 to 4 hours of being hooked up to the battery charger.
If the battery is really low then it could take 4 hours to fully charge the battery up again.
If the battery is only partially dead and just a bit low then it can take only 2 hours to fully charge the battery.
Just don't leave the battery charger on the car battery longer than 8 to 10 hours or it could cause the battery to overcharge.
If you plan to leave the battery charger on the car battery longer than 10 hours you should charge the battery on the trickle charge setting.
The trickle charger setting will charge the battery slower at lower amps and will allow you to leave the charger on the battery longer without risk of overcharging the battery.
For me in my experience when I need to charge a battery on a vehicle it takes around 4 hours to get a full charge into the battery when the battery is really low.
If the battery has a dead cell in it then it may not recharge properly and then in that case you would need to replace the battery.