Battery charging apparatus and method
First Claim
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.
3 Assignments
0 Petitions
Accused Products
Abstract
A battery charging apparatus and method is disclosed. The battery charger includes a programmable two level constant current source having an inhibit input. A clock signal is fed to counting stages which time out after a specified time, during which time the battery is charged with constant current. A temperature sensing circuit detects the temperature of the charging battery and will allow the battery to charge at a reduced rate for a longer time period if the temperature increases above a threshold level. Once the counting stages time out, the battery charger pulse charges the battery at the reduced current level, preferably at a 20% duty cycle, at relatively long intervals to keep the battery from self discharging.
-
Citations
25 Claims
-
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 interval means 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. - View Dependent Claims (2)
-
-
3. The battery charger recited in claim 3 wherein the magnitude of the pulses of said pulsed current is substantially the same as said second reduced constant current rate.
-
4. A method for charging a battery, comprising the steps of:
-
charging said battery in a constant current charging mode, so as to substantially fully charge said battery, including the steps of; charging said battery at a first constant current rate; generating a timing signal which changes state after a predetermined time interval; generating a signal responsive to the temperature of said battery if the temperature of said battery exceeds a predetermined temperature; said step of charging at a first constant current rate continuing for said predetermined time interval or until said signal responsive to the temperature is generated, said battery being thereafter charged, if said signal responsive to the temperature is generated, at a reduced constant current rate for a second time interval; and charging said battery with a pulsed current after said constant current charging mode has terminated so as to keep said battery from self-discharging after said battery is substantially fully charged. - View Dependent Claims (5, 6, 7, 8, 9)
-
-
10. A battery charger comprising:
-
controlled current source means which can be coupled to a battery to be charged having a first input for determining the current, from two different constant current levels, sourced by said current source means to said battery and a second input for inhibiting the sourcing of current to said battery; means for generating a first 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; counting means for generating a second signal which changes from a first state to a second state after a time interval; and means for generating a pulsing signal responsive to said second signal; said first input of said current source means responsive to said first signal and said second signal, said second input responsive to said pulsing signal when said second signal is in said second state, said current source means delivering a constant current determined by the state of said first signal when said second signal is in a first state so as to substantially fully charge said battery and delivering a pulsed current to said battery when said second signal is in said second state so as to keep said battery from self-discharging after said battery is substantially fully charged. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
21. A method for charging a battery, comprising the steps of:
-
charging said battery in a constant current charging mode, so as to substantially fully charge said battery, including the steps of; charging said battery at a first constant current rate; generating a timing signal by counting at a first timing rate so as to count for a predetermined time interval; generating a signal responsive to the temperature of said battery if the temperature of said battery exceeds a predetermined temperature; said step of charging at a first constant current rate continuing for said predetermined time interval or until said signal responsive to the temperature is generated, said battery being thereafter charged, if said signal responsive to the temperature is generated, at a reduced constant current rate for a second time intereval, said second time interval determined by counting at a second reduced timing rate, said second timing rate related to said first timing rate so as to be substantially inversely proportional to the ratio of said first current rate to said reduced current rate; and charging said battery with a pulsed current after said constant current charging mode has terminated so as to keep said battery from self-discharging after said battery is substantially fully charged. - View Dependent Claims (22, 23, 24, 25)
-
Specification