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Author Topic: What is/are the difference(s) between a 'flat' and a 'dead' battery?  (Read 5723 times)

Offline Chemistry4me

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You can jump start a dead battery right? But not a flat one? So what is/are the difference between the two?

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Oh yeah, and by battery I mean the lead-acid ones in your car.
« Last Edit: 28/05/2009 07:26:32 by Chemistry4me »


 

Offline techmind

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You can jump start a dead battery right? But not a flat one? So what is/are the difference between the two?

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Oh yeah, and by battery I mean the lead-acid ones in your car.

I doubt that 'dead' and 'flat' should be taken to have too specific a meaning.

That said, there is a difference between a battery which is simply run-down and would wholly recover if charged (you might call that 'flat')
and one which is worn out, its electrodes are buckled and damaged, there's sludge in the bottom, and it won't hold much charge even if you try (you might call that 'dead').

I'm no expert on Pb-acid batteries, but I believe that leaving them flat for extended periods of time hastens their becoming 'dead' (irrecoverably damaged).
 

Offline Chemistry4me

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I'm no expert on Pb-acid batteries, but I believe that leaving them flat for extended periods of time hastens their becoming 'dead' (irrecoverably damaged).
When all the lead sulphate falls off the electrodes right?  [xx(]
 

Offline Don_1

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I think I would go along with techmind's explanation.

Dead - Cannot be re-charged
Flat - Can be re-charged.
 

Offline Chemistry4me

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Okay, so I've got it the wrong way round.
 


Offline Chemistry4me

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Thank you. :)
 

lyner

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It's a bummer but I understand that most 12V accumulator batteries will soon be 'dead' if you discharge them to below Half their stated capacity. That, to my mind, offends trades description laws but they all do it!
 

Offline techmind

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It's a bummer but I understand that most 12V accumulator batteries will soon be 'dead' if you discharge them to below Half their stated capacity. That, to my mind, offends trades description laws but they all do it!

I thought it was ok as long as you only fully discharged them occasionally and then recharged them pretty soon - but Pb-acid is not my speciality. Pb-acid likes to be kept topped-up and fully charged.

All batteries have their quirks.

Li-Ion on the other hand degrades over time (capacity fall c.30% per year) almost irrespective of how much you use them - but with even quicker deterioration if you keep 'em topped up. They die and become incendiary if they get too flat (metallic Lithium), and lose capacity fast if kept fully charged. This is why they supply them about 35% charged when they leave the factory...
 

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