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#204758 - 01/05/12 08:24 PM DC battery and earth ground
frank Offline
Member

Registered: 05/29/01
Posts: 361
Loc: windsor ontario canada
Will a car battery slowly discharge if the positive is left diconnected and the negetive treminal is connected to a ground rod.No circuit would be made back to the source so no current would flow is my first intuition but then the how do you expain capasitive circuits.Since earth ground is 0 reference would there not be a potential for electron flow?


Edited by frank (01/05/12 08:24 PM)

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#204759 - 01/05/12 09:50 PM Re: DC battery and earth ground [Re: frank]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
The short answer is no. You just have to be sure there is no discharge path. The capacitive effect is nil on a DC circuit. It only affects a changing voltage. Any DC current you see across a capacitor is actually a fault.
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#204760 - 01/05/12 10:39 PM Re: DC battery and earth ground [Re: frank]
frank Offline
Member

Registered: 05/29/01
Posts: 361
Loc: windsor ontario canada
Greg,
Thanks for you response.I hate to be a pain but could you elaborate on what you mean by "You just have to be sure there is no discharge path"DC theory has never been my strong suit and I want to fully understand this question as pointless as it is.Believe it or not two electrical engineers came up with a definitive "I don't know" after mulling it over.Sorry for my atrocious spelling as I was in a hurry typing my last post.


Edited by frank (01/05/12 10:41 PM)

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#204763 - 01/06/12 07:39 AM Re: DC battery and earth ground [Re: frank]
jdevlin Offline
Member

Registered: 08/07/02
Posts: 402
Loc: welland ontario canada
In theory it would not. However batteries are a chemical reaction that is ongoing. A battery will slowly lose its charge just from internal losses.
You can also lose charge if the battery is dirty on top. There can be discharge across the top of the battery through the dirt.

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#204764 - 01/06/12 11:37 AM Re: DC battery and earth ground [Re: frank]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
Mr Devlin has summed it up well, If the top of the battery is dirty, it can create a fault path that will slowly discharge a battery, even if one terminal is disconnected.
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Greg Fretwell

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#204783 - 01/09/12 05:00 PM Re: DC battery and earth ground [Re: frank]
mikesh Offline
Member

Registered: 06/07/06
Posts: 614
Loc: Victoria, BC, Canada
Batteries do self discharge. Even very stable batteries like lithium have a shelf life and eventually will die on the shelf.

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#204784 - 01/09/12 05:56 PM Re: DC battery and earth ground [Re: frank]
JoeTestingEngr Offline
Member

Registered: 11/04/05
Posts: 786
Loc: Chicago, Il.
So if you want the battery to be any good many months from now, a float charge is in order. It doesn't take much current after the battery is topped off. That is with a battery cable removed.
Joe

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