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Battery charging apparatus and method

  • US 4,554,500 A
  • Filed: 03/31/1983
  • Issued: 11/19/1985
  • Est. Priority Date: 03/31/1983
  • Status: Expired due to Term
First Claim
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1. A battery charger comprising:

  • controlled current source means which can be coupled to a battery to be charged for sourcing current to said battery and having an inhibiting input for inhibiting the sourcing of current;

    counting means for generating a timing signal which changes from a first state to a second state after a time intervalmeans for generating a two-state signal responsive to the temperature of said battery being charged, said signal being in a first state when said battery is below a threshold temperature and being in a second state when said battery is above said threshold temperature, said current source means having a further input for determining, from two different constant current levels, the current sourced by said current source means to said battery, said further input responsive to said two-state signal so as to charge said battery at a first constant current rate when said two-state signal is in said first state and to charge said battery at a second, reduced constant current rate when said two-state signal is in said second state, said battery being substantially fully charged at one of the first, second or combination of the first and second current rates when said timing signal is in said first state; and

    means for generating a pulsing signal;

    said inhibiting input of said current source means responsive to said pulsing signal when said timing signal is in said second state, said current source means delivering a pulsed current to said battery when said timing signal is in said second state so as to keep said battery from self-discharging after said battery is substantially fully charged.

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