How long does it take to charge a car battery?

I havent used my car for a couple months and the batterys gone dead so i borrowed my friends car battery charger and let it charge overnight and its still not charged?How long does it take to charge a car battery?
It's probably one of those cheap **** chargers. You might be better off attempting to get a jumpstart and let it run for a while.
Mad Jack is right about taking longer for a badly discharged battery. Also most portable "Home type" chargers are only trickle chargers and take forever on a badly discharged battery. If it doesn't come up in a bit longer try taking it somewhere where they have a full service charger that can do first a high level charge then a taper charge to finish up. Further, if the battery was connected to the system the entire time it may be so far discharged that it's no longer serviceable and needs to be replaced. If you know you aren't going to drive for several months it's best to remove the negative lead from the battery.How long does it take to charge a car battery?
The battery should be fully charged after 8 hours. The battery could be defective. I would suggest that you make sure that the battery charger is properly connected and that it is making a good connection.



The simplest method for checking your connection is to use the headlights.



First, turn on the headlights before you connect the battery charger. They should be very dim or not working at all if the battery is completely dead.



Next connect the battery charger and turn it on. (It will probably spark right when you connect it, that is normal, however, if it continues to spark or starts smoking, unplug the battery charger from the wall outlet)



If the headlights come on or get brighter when the charger comes on, you know that you have a good connection. If this is the case, turn the headlights back off and let the battery charge for a few hours.



If the lights do not get brighter, then you have another problem, such as a defective charger, bad connection, or bad battery. Be sure your battery cables are snugly connected to the battery and free of corrosion, as the battery cable connection is probably the most common cause of cranking issues.



Sorry I wrote you a book, but hopefully it will help.
Typical car battery holds 70 amp-hours, and typical small lunchbox sized charger is 10 amps, so 7 hours. A bit longer due to inefficiency. Check your charger and do the math. If you have one of those tiny cigarette pack sized 1 amp trickle chargers, might be longer, you guessed it, 70 hours :)



You don't need to fully charge the battery to start the car. As long as it starts, once it's started it will recharge the battery.



How old is the battery? Lead-acid car batteries tend to wear out after about 5 years give or take. If it's older, it may just be shot and need replacing.



Make sure you're charging it properly, i.e. the ammeter shows a strong charge at first and then tapers off.



Make sure the area you're doing this is well ventilated. Batteries put out hydrogen gas when charging, especially if the battery is worn out. If you think that gas might have accumulated, don't do anything to make a spark, i.e. don't unhook the charger. Ventilate the room to outside.How long does it take to charge a car battery?
Can you pop off the maintenance caps? Can you see the fluid level inside? If low, top up with distilled water. If you trickle charged it for a long period, and it's still no good, have it professionally load tested. Conventional car batteries dislike being fully discharged. Your battery may be toast.
If the battery has completely failed, it may not take a charge.



The amount of time it takes to charge an automotive battery depends on how discharged the battery is, the amperage rating of the battery, and the charging rate of the battery charger you are using.



Many of the new fully automatic electronic battery chargers will not charge a battery if it is bad. If the battery is too dead or fails initial tests this type of battery charger will switch to desulfation mode. In this mode it will send high frequency electronic pulses through the battery plates to remove sulfur deposits. Then it will attempt to charge the battery. If the charger still detects problems with the battery it will not charge the battery and a fail light will illuminate on the battery charger. If the battery is good it will take about 8 to 10 hours to fully charge the battery and this type of automatic battery charger will stop charging so the battery is not over charged.



If you use a older style manual or automatic battery charger it will still take some time to charge a battery. As a very general amount a time it will take about 8 to 10 hours to fully charge a car battery with a 10 amp automotive battery charger.
Yes, take it off and try it. You've got nothing to loose....



Without knowing how many amps you are using here



it's hard to say how long. Even a slow 2 amp charger should



have brought it back enough to start the car.



Go for it...
Depends on how many amps the charger puts out. 2amp charger, may take well over a day. 10amp should charge overnight.
It should take a few hours for it to get a good charge.