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Muti chemistry charger..

Discussion in 'Electronic Design' started by cafm, Jul 6, 2005.

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  1. cafm

    cafm Guest

    Hi guys,

    i am doing my 4th year..7th sem... garduate degree in Electronics and
    Communication and am looking to do a good project that will have some
    practical use.
    on of the peojects i studied the feasibilty was of a a multi chemistry
    charger. I read up on the chemistry of batter charging and here are
    some points.
    (*)Intended Chemistry
    (1) NiCd
    (2) NiMH
    (3) Li Ion
    The reason for excluding SLA sealed lead acid is the ratings that i am
    planning to build for is around 15v tops (+2 differential) and around
    2-3 A.

    (*) Smartness
    some pretty straight forward chargeing and discharging sampling should
    allow for chemisty detection but this is currently a stumbling block
    since there are no experiment data available

    (*) Efficieny...plan to get the constat current by PWM switching in a
    feedback control sytem with uC as intelligentce....should be enough

    (*) Cost???...
    (*) Noise...Swithcing noise will be eliminated using a proper filter..
    (*) Battery life...may implement pulse charging to increase life
    (*) Speed Fast charging with proper EOC...

    currenlty the only charger that i could find that indentifies and
    charges properly is
    bq2000 Programmable Multi-Chemistry Fast-Charge Management IC
    a similar thread is "Battery Charger IC's"
    i plan to improve on any of its trade offs

    cost for this is about 1.7 $ per KU but requires external switching
    supply

    dicrete implementaion may not present a cost saving though


    currenly i am trying to figure out chemistly identification part.

    any suggetions are welcome in any area

    any other good projects ideas are also welcome...i have some free time
    on my hands and dont want to waste it all up on football manager 2005
    and Age of conqurors...lol

    thank you
    cafm
     
  2. Excellent subject.
    http://www.seabird.com/pdf_documents/manuals/NiMH_001.pdf
    section 5
    These people actually measure the Kjoules charged, rather on A/H. Many
    users need a reasonably accurate measure of how much battery life is
    remaining. This, I think, is quite a challenge.
    Have a look at www.TI.com for INA138, or similar at www.linear.com

    Many laptop batteries have EEPROMS embedded in them, mainly to prevent
    us using non original replacements. Consider putting an open source
    "charge status" in something similar. It's probably been done, but
    worth investigating


    martin
     
  3. cafm

    cafm Guest

    thank you...will follow up on that....and post what i get....
     
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