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Impedance matching for battery charging?

  1. May 8, 2015 #1
    Hi all, I am wondering if there is a need for impedance matching to charge a battery from the source? Thank you
  2. jcsd
  3. May 8, 2015 #2


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    No need for impedance matching of the transmission line type but the charging source impedance/resistance usually should be relatively in range of battery internal charging resistance to deliver the maximum recommended current at the needed difference in charging voltage from the flat battery voltage when fully discharged. This is usually handled by 'circuit' using a current source set to max charge current with a voltage limit set to max charging voltage. This 'circuit' doesn't have to be strictly electronic, a properly designed 'battery charging' transformer and rectifier can have the same effect.
  4. May 9, 2015 #3
    Thank you Nsaspook :)
  5. May 11, 2015 #4


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    Lot depends what you are doing. The charging algorithm you need depends on the type of battery. Some need/prefer constant current, others are ok with constant voltage and a current limit. The way you detect the full state also varies depending on the cell type and the speed of charging. Some can tolerate long term overcharge, others can't. Some cells should not be charged when very cold. Some shouldn't be fast charged if they are hot or have been discharged below a certain voltage.
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