battery capacity

Discussion in 'Homework Help' started by petercl14, Oct 5, 2012.

  1. petercl14

    Thread Starter New Member

    Sep 29, 2012
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    I have been using deep cycle lead acid and ni-mh batteries and it has become quite clear to me now that a new battery needs to be used quite a few times before its capacity increases to a maximum. this capacity seems to be 50% or more from its new capacity.
    for instance I have a new 6,800 mah ni-mh battery which is not lasting as long as my well used 4,600 mah ni-mh battery. I would have said that the 6,800 battery was not really this capacity if I didn't know better. the 4,600 mah was also depleting rapidly when new and not storing much charge in the first place.
    It is the same with my 55 a/h agm battery. When new it was not lasting long at all but now I get a very good result from it after using it quite a few times.
    I don't know if this is well known or not, but I have never seen anything on it. Does anyone know the reason for this and would I be able to understand the explanation if it is not a complicated chemical engineering problem. a battery is of course a chemical reaction delivering a electric current
    Anybody else noticed this in batteries and knows the reason? is there any good literature on this giving for instance the number of times the battery has to cycled before it reaches its maximum storage capacity?
     
  2. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    I have never heard of this problem with lead acid (AGM) batteries. Ni-Mh should not be doing it either. Lead acid typically show max capacity new and gradually decline with cycles. I am not sure why yours are doing this.

    The only thing I can think of is perhaps the "new" cells sat on the shelf too long and grew some internal bridges that were current paths to degrade capacity and they burned away with cycling.
     
  3. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
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    Most recommend doing an initial charge on a new battery.
     
  4. petercl14

    Thread Starter New Member

    Sep 29, 2012
    3
    0
    that sounds like a distinct possibility" bounty hunter." I obtained the batteries through e-bay and got them cheaper than normal probably because they had been in the sellers possession for too long.
    does that really happen i.e. internal bridges in the battery? anyway your explanation certainly would explain the facts.
    does anyone else out there have any further ideas or agree with bounty hunter.
     
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
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    I know older Ni-Cads and NI-Mh grow internal bridges after the separators degrade over time.

    I did get a new lead acid motorcycle battery once (shipped dry) that had an internal bridge of some kind. When I added the acid, it got very hot without any charging (I quickly set it way out in the back yard by the fence). It cooled down but would not take a charge. I let it set a week and then charged it up and down a few times and it then worked normally.
     
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