Power from a PPE 9v battery

Discussion in 'The Projects Forum' started by stevy123, Mar 9, 2008.

  1. stevy123

    Thread Starter Active Member

    Nov 19, 2007
    61
    0
    Hi All

    I have a circuit which i am powering from a 9V PPE battery. The circuit is drawing 300mA, how long should i expect the battery to last?

    Anyone know the formula to work this out?
    How much longer would i get if i was using 8 AA 1.5 batteries to give me 12V?

    Thanks in advance
    Steve
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    What is the meaning of PPE?

    hgmjr
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I think Steve is talking about PP3 9V "Transistor" batteries.
    How long the battery will last depends upon the construction of the battery.
    Typical Capacity
    (mAh)
    565 (alkaline)
    400 (carbon-zinc)
    1200 (Lithium)
    120 (NiCd)
    175 to 300 (NiMH)
    500 (Lithium polymer rechrg)

    Let's say you use a lithium cell. 1200/300 = 4 hours - not long.

    You could use six 2500mAh AA batteries to get just over 8 hours of operating time.
     
  4. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    If you are referring to PP3 then based on the mAh (milliamp-hour) ratings that sgtwookie has provided then you can estimate the duration of an alkaline type 9V battery with a load of 300 milliamps to last approximately 565/300 = 1.88 hours or 113 minutes.

    The same means of calculation can be used to estimate the duration of for each of the battery types that sgtrwookie has listed.

    hgmjr
     
  5. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Why not look at the datasheet of a 9V battery like Energizer's alkaline battery. www.energizer.com
    1) Its voltage does not stay at 9V, It drops quickly to about 7.2V then drops slower to nothing.
    2) Its capacity with only a 25ma load is 625mAh but then its voltage has dropped to 4.8V.
    3) With a 300mA load, it reaches 6V in a little less than 1 hour.

    Here is its voltage curve with a 250mA load.
     
  6. stevy123

    Thread Starter Active Member

    Nov 19, 2007
    61
    0
    thanks for your replies guys, most helpful :)
     
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