Extending battery life with parallel batteries?

Discussion in 'The Projects Forum' started by susannah, Apr 28, 2016.

  1. susannah

    Thread Starter Active Member

    Feb 14, 2010
    87
    0
    I want to extend time i can use my Olympus voice memo recorder.

    It uses one AAA battery.

    Can i just solder wires to battery bay + and - contacts and put many AAA batteries in parallel?
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,795
    951
    That would be acceptable. Do not mix battery types. Batteries should all have the same charge state. Don't mix old and new batteries.
     
  3. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,041
    1,671
    Yes or just use on larger battery like a AA, C or D size.
     
  4. MrAl

    Well-Known Member

    Jun 17, 2014
    2,440
    492
    Hi,

    Yes AA batteries are about twice as 'strong' as AAA batteries. They can run something two times longer.

    Also, the batteries have to all have the same voltage.

    When functioning off of one battery, the battery experiences a discharge rate of I*K where K is a constant and I the current, but when we divide the current by 2 (two equal batteries in parallel) the discharge time goes up by a factor that is greater than 2 because of the P factor of the battery, which means that the ampere hour capacity actually goes *UP* with lower current levels.
    The usual test level is C/20, and at higher currents the run time goes down by the ratio of C/20 to the actual discharge current level, minus a little more, but at lighter currents it goes up by a little bit more.
    So at lower current levels the batteries look like they are bigger than they really are. That means more than twice the run time from two equal batteries in parallel.
    Some care has to go into the matching of the two (or more) however.
     
    RamaD likes this.
  5. wayneh

    Expert

    Sep 9, 2010
    12,153
    3,059
    Be careful if you buy a commercial battery pack, such as one for holding 2 or 4 AAs. They are usually wired to put the cells in series instead of parallel. This would over-voltage your device.
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    Depending upon how long you want the device to operate, just use an AA, C, or D cell, as mentioned by tcmtech.
    They have the same capacity as about 2, 6 and 12 AAA cells respectively.
     
    RamaD likes this.
  7. MrAl

    Well-Known Member

    Jun 17, 2014
    2,440
    492
    Hi,

    I dont know if anyone has every taken a 9v alkaline battery apart, but they used to house AAAA batteries inside. Many of them now have little flat batteries stacked in series.
    The little AAAA batteries where skinnier than the AAA batteries.
     
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