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Battery power for portable application

Discussion in 'Electronic Design' started by mook johnson, Jul 22, 2004.

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  1. mook johnson

    mook johnson Guest

    I have a 150mW(avg) 3.3V design that I need to run off as small a battery as
    possible and provide at least 16 hours of service. I will be using a boost
    or buck or switched cap converter (80+% efficient) to convert the battery
    voltage to 3.3Vdc throughout its discharge.

    Looking at coin cell(2) lithium (very low current ratings), AAA Duracell's
    or as a last resort as 9V.

    How do I choose the smallest battery possible? Price difference between
    these is not an obstacle.
     
  2. Ian Stirling

    Ian Stirling Guest


    Be carefull abvout the selection.
    If using a 1.5V battery, a lot of the switchers sticker efficiancy
    is very misleading, as if you look at the graphs, it's horrible
    efficiency at the lower end of 1.5, as the power devices response
    degrades.
    You pick the smallest battery possible that will deliver 150mW for 16
    hours.

    Zinc-Air is probably the smallest way to get 2400mWh.
    However, it won't generally support being drained as fast as 16 hours.

    Is price a consideration?
    An AA lithium 1.5V cell will do the job.
    I don't think you'll get there with AAA 1.5V.

    For a smaller one (27mm long, 15.6mm dia), 3 volt camera batteries
    (DLCR2) are available that might suit.
     
  3. I read in sci.electronics.design that Ian Stirling
    reader01.plus.net>) about 'Battery power for portable application', on
    Thu, 22 Jul 2004:
    Well, not 16 hours continuous, but is 'continuous' a requirement. 16
    hours intermittently is probably OK
     
  4. Ian Stirling

    Ian Stirling Guest

    IIRC, if you drain them at a rate which is shorter than 24 hours or so,
    then they perform very poorly.
    Also they only live some weeks/months if not used and open.
     
  5. Joerg

    Joerg Guest

    Hi Mook,

    Take a look at the popular camera battery Panasonic CR-V3. It should pack enough energy but is a bit expensive. The nice Li discharge curve might allow the switcher to add just the 0.3V on top of Vbat unless you could live with 3V instead of 3.3V.

    Regards, Joerg
     
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