Choosing A battery

Discussion in 'General Electronics Chat' started by RodneyB, Apr 3, 2015.

  1. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
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    I need to choose a battery pack for a project I am working on. The stand by current is 40mA and the operating current can go as high as 2Amps albeit for less than a second.

    In the past I have used batteries purchased over the counter but it has dawned on me that possibly often the battery is an overkill.

    I understand the connection of cells in series and parallel, and a battery has a Ah capacity which determines your back up time.

    What I am trying now to find out is how I use a battery and what I look for. I know I can join 4 x 3.7 Volt AA cells together to get 14.8 Volts but I cant run a high current drawing device from it. So I want to understand when looking at a battery just what I must be looking for. Then How to work out the back up time .
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    you can put cells in parallel to give higher capacity, so for example two cells 3.7V @ 1800maH , will give 3.7V @3600maH ,
    whereas in series would give 7.4V @1800maH,

    so choose a battery that gives you the desired voltage and current and put them in series or parallel if needed.
     
    RodneyB likes this.
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    cmartinez, dl324 and RodneyB like this.
  4. PlasmaT

    Member

    Feb 19, 2015
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    If the 2 amps is the inrush current, you could try using a high value capacitor in parallel to the source.
     
  5. Ramussons

    Active Member

    May 3, 2013
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    You beat me to it :D
     
  6. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
    633
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    The current is not the in rush current. The datasheet states the unit can reach 2 amps during operation. So far I have not seen it go over 30ma but then I have not checked all the features
     
  7. PlasmaT

    Member

    Feb 19, 2015
    40
    6
    So its not the inrush current...., but the current is not very high too, so I suggest going for a 6V lead acid battery with a booster to get to the required voltage.
    :rolleyes: how much voltage you need anyway? It is 14.8V?:confused:
     
  8. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
    633
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    Size is also a big thing here. I am yet to get the unit to operate over 100mA
     
  9. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
    633
    13
    Thanks Mike Good information.

    The GSM Module manufacture eventually answered my email and said this

    "It is perfect to run the GSM directly from the battery.
    Current consumption can be 2A but during GSM transmit only for a couple of microseconds.
    Some power supply can not handle this, but battery can."

    My question was could I use a 14.8 Volt 800mA LI-ION battery.

    Still don't have an answer
     
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