How Long To Charge A Totally Dead Car Batt?

[joko]

i am taking my car battery to be charged up at my mums house - it is totally dead - absolutely empty - as been unused for a while

about how many hours should i charge for to be sure it wont be dead again in a few days?

thanks

[woofgang]

If its that old and has been left flat, it may not hold a charge (or even accept one) If it will hold its charge, overnight should do it.

[Hopkirk]

Sometimes a totally dead battery won't recharge properly - I believe the plates can buckle and touch.

Brace yorself for the cost of replacement.

[gingejbee]

I agree with woof...and it depends on whether it's a simple "one-rate" charger, or a modern sophisticated one that can do clever things with a completely dead battery. Either way, you're not guaranteed a successful outcome.

[Clanad]

The previous posts should be heeded, but trying to recharge a totally dead car battery can also be dangerous for the novice.

If you try, be sure to check the fluid level in the battery if it's a model that isn't sealed. You can tell by it having 6 removable plugs on the top. Use caution since the acid in the battery is very corrosive... best to use gloves and eye protection (and really old clothes). If you find one of the cells (under the cap) quite a bit lower in fluid than others then the sucsess of charging the battery is in doubt since the really low fluid indicates a possibly damaged cell.

At any rate, fill the cells to the neck below the plug with distilled water only.

Next (personally, I'd take the battery our of the car) connect the charger to the correct polarity terminals... plus (+) to plus and negative (-) to negative with the charger not plugged into an electrical outlet. Once connected to the battery, then plug it into an outlet. Watch the rate-of-charge needle on the charger. It will completely peg as the starting amperage draw is quite high and will probably remain so for some time. This is where things can become dodgy since the high amp rate can cause considerable heat, possibly causing the battery to explode. The amperage rate should taper off to a mid-reading on the gauge within a couple of hours or so. If it extends beyond that then you no doubt have a failed battery and need to buy a new one.

It'll take maybe 10 to 12 hours to fully charge the battery if it's going to work...

Be sure the terminals are clean by the way. If there's corrosion (green gunk) around the terminals, especially the positive one, clean it with a bottle of Coca Cola or 7UP poured over it... dry it with an old expendable rag once done...

Luck!

[cleggie]

just buy a new one .you know its ok not going to let you down its got some guarantee etc.

[joko]

this one is only just a year old...

[stocksman]

The important thing to remember is never ever take the charger clips on or off the battery while charger is switched on. Batteries give off highly explosive gases, even when not attached to charger and when you attach or detatch the clips it causes a spark which could cause explosion. This is not a problem providing the charger is not plugged in to mains socket. The best way is to attach positive clip to battery first and then attach negative clip to an earth point on bodywork or engine. This way if there is a spark it is not near the battery gases.