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  1. #1
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    Lead Acid + Super-Capacitor + DC/DC Converter

    Is it possible to combine lead-acid batteries with super-capacitor cells in a DC-DC converter? I have gone through few research articles at IEEE but could not find a simple practical system for EVs.

    What I need is to maintain the lead-acid battery capacity when high current is drawn (Peukert Law) and, that current should be supplied by the super-capacitor bank. All this should be combined in a 3kW DC-DC converter for Vin = 24V and Vout = 60V.

    Any suggestion for design or reference to some research article with measurement results or, reference design will be appreciated.

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  2. #2
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    Re: Lead Acid + Super-Capacitor + DC/DC Converter

    Check the data sheets on your super caps - only the very best ones - read expensive - have low internal ESR.

    for 3kW 24Vin this is 125 amps, for a super cap to supply this efficiently its total ESR will have to be 6.4milli-ohm for 100 watt internal dissipation

    let me know if you find a combination of paralleled super caps that can do this

    even at 50A from the super caps and 10W internal this is 4 m-ohm

    "Super" caps are not that super ....



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  3. #3
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    Re: Lead Acid + Super-Capacitor + DC/DC Converter

    To produce your desired power and step-up ratio, you'll probably need to make the boost converter draw some supply current at all times. Input filtering may provide only slight benefit.

    Here is a simulation. 24V supply. Output is 60V @ 50A.

    Click image for larger version. 

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    Scope traces show it's possible to adjust frequency and duty cycle so that supply current doesn't shut off entirely.



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