Can any current flow out of battery if negative cable disconnected?

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Old 09-11-08, 06:44 AM
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Can any current flow out of battery if negative cable disconnected?

A lady at this apartment complex has an overnight voltage loss in her 1 year old battery. It is one of those smaller type batteries. Someone suggested to her these are junk.

I have been giving her jump starts, when I catch her home, and suggested she remove the negative cable on the battery overnight to see if the battery retains voltage of not. And yes, the battery has been leaking out. The volts were about 8.5, and it starts instantly with jumper cables, and votls become about 14.3 when idling. After key shut off after 1/2 hour of idling volts are at 12.36.

But I got wondering that if some component in a vehicle is shorting to ground and bleeding out some current overnight, that even if you disconnected the negative terminal, could current still flow out of the postive terminal, even a little bit?, into a lot of steel mass, without necessarily needing the return loop to the negative battery post?

It seems to me that with *AC* current, that if you have enough metal mass that current likewise can flow into that, without the metal being grounded.
 
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Old 09-11-08, 07:37 AM
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A battery wouldn't drain to outside the battery without the negative post grounded. However, it can be a defective battery and not hold a charge, having been charged, and left overnite without either post hooked up.
 
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Old 09-11-08, 08:18 AM
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Marbobj is correct, no connection no drain,she has a faulty battery. Now when she gets the new battery installed and it is the correct one, you can put a voltmeter in sequence and she if she has a drain that would have killed the battery.
 
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Old 09-11-08, 08:55 AM
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I have heard, but never witnessed it, that a really dirty battery could self discharge between terminals, under the proper conditions. It is probably an " old wives" tale.

You might check for a hood, glove compartment, or trunk light that is stuck on. She could take the car to someone like Autozone, who will do a free battery test to see if the battery is really bad or if something else is dragging it down.
 
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Old 09-11-08, 03:07 PM
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I have heard, but never witnessed it, that a really dirty battery could self discharge between terminals, under the proper conditions. It is probably an " old wives" tale.
Nope ....absolutely true.....The same theory holds to storing batteries on a concrete floor.....

BUT......This is more likely a case of a degraded battery....
 
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Old 09-11-08, 03:18 PM
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We do not know YET if the battery is defective. The battery has not been disconnected yet.

I wanted to find out for sure, that when I told her to disconnect the negative cable, that no current could leak out of some shorted component on the car.

Bulbs that are under the hood, on door side panels, trunk, visor, are not on.

I suggested we start by disconnecting battery, but that is up to her to get out there, or get her son or even mechanically inclined daughter-in-law out there, in the dark after she gets home at night, to do so.

At least now I feel good I told her the right thing, and no current can come out thru the positive cable. That must mean then it is okay, if the negative cable is disconnected, that you can actually ground the positive cable to your cars engine and frame, and absolutely no curent can leak out then.
 
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Old 09-11-08, 04:47 PM
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Nope ....absolutely true.....The same theory holds to storing batteries on a concrete floor.....

True back in the rubber cased battery day. Not so with today's plastics.
 
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Old 09-11-08, 06:29 PM
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True back in the rubber cased battery day. Not so with today's plastics.
Actually, Just this week, we returned 30 batteries, that were stone dead, when the vendor didnt have a Pallet to load them on.....They were only in the "Stock Hold" for maybe a week.
 
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Old 09-12-08, 06:06 AM
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What is the cause of this exactly?
 
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Old 09-12-08, 09:43 AM
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Some may find this site interesting. It relates to battery myths.

http://jgdarden.com/batteryfaq/carfaq14.htm
 
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Old 09-12-08, 09:59 AM
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Storing modern batteries on a concrete floor is NOT a problem! It is amazing how old out of date information continues to be passed out as current, up to date facts!

http://www.batteryfaq.org/


14.1. MYTH: Storing batteries on a concrete floor will discharge them.

False! All lead-acid batteries will naturally self-discharge which can result in loss of capacity from sulfation. The rate of self-discharge is most influenced by the temperature of the battery's electrolyte and the chemistry of the plates. This self-discharge is often mistaken for concrete floor causing the battery to drain. Some experts believe that storing car or deep cycle batteries on a colder concrete floor might actually slow down the self-discharge (leakage) rate because the floor acts as a heat sink and cools the battery. (Please see Section 13 for more information on storing batteries and Section 1 for more information on sulfation.

In the early 1900s, when battery cases were made of porous materials such as tar-lined wood boxes, storing batteries on concrete floor would accelerate their natural self-discharge due to external leakage. Modern battery cases are made of polypropylene or hard rubber. These cases are sealed better, so external leakage-causing discharge is no longer a problem, provided the top of the battery is clean and free from wet or dried electrolyte and the same temperature as the floor.

Large differences in temperature could cause electrolyte stratification within very large batteries (>250 AH) which could accelerate it's internal "leakage" or self-discharge if the battery is sitting on an extremely cold concrete, stone or steel floor in a warm room, boat or submarine. Stirrers or bubblers are often used on these types of large batteries to keep the electrolyte from stratifying. Undercharging will also cause electrolyte stratification, which can also result in loss of capacity from sulfation.
 
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Old 09-12-08, 03:30 PM
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14.1. MYTH: Storing batteries on a concrete floor will discharge them.
In a memo from Daimler Chrysler, We were instructed to raise all "Unused Stock" Batteries a minimum of 3 inches above the floor using wooden blocks, or other suitable "Non Conductive materials"....Wooden "Skids" Are Deemed Acceptable.
 
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