Battery charger with three different charging rates

Claim 2

A three level battery charging circuit comprising: a dual rate charging circuit connectable across the terminals of a battery to be charged and including an automatic switch means for automatically switching from a first charge rate to a second lower charge rate in response to a sensed battery voltage in excess of a first predetermined threshold voltage; a further charging circuit providing charging current at a third rate higher than said first rate and connected in parallel with said dual rate charging circuit; and control means connected to control said further charging circuit so as to switch it to active condition in response to a sensed battery voltage in excess of a second predetermined threshold voltage which is less than said first threshold; whereby, for a fully discharged battery, the following sequence of charging rates is provided: (a) said first rate, (b) the combination of said first rate and said third rate, (c) the combination of said second rate and said third rate, and (d) said second rate.

Claim 3

A three level battery charging circuit as in claim 1 wherein said dual rate charging circuit comprises: a voltage reference connected to a voltage comparator and switch circuit including first and second resistances connected in series with the battery to be charged and shorting switch connected in parallel with at least one of said resistances.

Claim 4

A three level charging circuit as in claim 2 wherein said control means includes means for automatically turning said further charging circuit on and off in response to sensed battery voltage and temperature conditions so that said third charge rate is applied to the battery only under predetermined conditions of temperature and sensed battery voltage.

Claim 5

A three level battery charging circuit comprising: first means for applying continuous battery charging at a first rate for bringing a battery from a fully discharged state to a predetermined level for receiving a higher charge rate; second means for applying battery charge at a second rate higher than said first rate for rapid battery recharge; and third means for applying continuous battery charge at a third rate lower than said first rate to sustain full charge on the battery once a predetermined battery voltage is reached said first, second and third means being interconnected and inter-related to produce the following sequence of charging rates for a fully discharged battery: (a) said first rate, (b) said second rate, and (c) said third rate.

Claim 6

A three level battery charging circuit comprising: first means for applying continuous battery charging at a first rate for bringing a battery from a fully discharged state to a predetermined level for receiving a higher charge rate; second means for applying battery charge at a second rate higher than said first rate for rapid battery recharge; and third means for applying continuous battery charge at a third rate lower than said first rate to sustain full charge on the battery once a predetermined battery voltage is reached said first, second and third means being interconnected and inter-related to produce the following sequence of charging rates for a fully discharged battery: (a) said first rate, (b) said second rate, and (c) said third rate.

Claim 7

A circuit for charging a battery at differing combinations of three charging rates: (a) a first charging rate for bringing battery from discharged state to a predetermined level for high rate charge; (b) a second rate charge higher than said first rate for rapid battery recharge, and (c) a third charging rate lower than said first rate to sustain full charge on the battery once charging to a predetermined battery voltage is reached, said circuit comprising: rate control means for (1) determining when said battery is within predetermined limits for said second rate changing, and (2) applying said second rate charge to said battery while said battery is within said predetermined limits; voltage comparator means for comparing said battery voltage with a reference voltage; source means for applying a continuous charging voltage and current to a battery; first and second resistance means for series limiting the continuous charging current applied by said source means; said first and second resistance means being connected in series with each other and in series with the battery and said source means to provide said first charging rate when at least one of asid resistance means is bypassed and otherwise to provide said third charging rate; and switching means for bypassing at least one of said first and second resistance means when said voltage comparator means detects said battery voltage increase beyond said reference voltage whereby, for a fully discharged battery, the following sequence of charging rates is provided: (a) said first rate, (b) the combination of said first and second rates, (c) the combination of said second and third rates, and (d) said third rate.

Claim 8

A circuit for charging a battery at differing combinations of three charging rates: (a) a first charging rate for bringing battery from discharged state to a predetermined level for high rate charge; (b) a second rate charge higher than said first rate for rapid battery recharge, and (c) a third charging rate lower than said first rate to sustain full charge on the battery once charging to a predetermined battery voltage is reached, said circuit comprising: rate control means for (1) determining when said battery is within predetermined limits for said second rate changing, and (2) applying said second rate charge to said battery while said battery is within said predetermined limits; voltage comparator means for comparing said battery voltage with a reference voltage; source means for applying a continuous charging voltage and current to a battery; first and second resistance means for series limiting the continuous charging current applied by said source means; said first and second resistance means being connected in series with each other and in series with the battery and said source means to provide said first charging rate when at least one of asid resistance means is bypassed and otherwise to provide said third charging rate; and switching means for bypassing at least one of said first and second resistance means when said voltage comparator means detects said battery voltage increase beyond said reference voltage whereby, for a fully discharged battery, the following sequence of charging rates is provided: (a) said first rate, (b) the combination of said first and second rates, (c) the combination of said second and third rates, and (d) said third rate.

Claim 9

A circuit as in claim 5 wherein said voltage comparator means comprises a transistor with a zener diode connected between said transistor emitter and ground, said transistor turning on when the voltage on the base of said transistor is greater than the base emitter voltage of said transistor plus the voltage across said zener diode.

Claim 10

A circuit as in claim 6 wherein said switching means comprises a transistor.

Claim 11

A battery charger system for charging each of a plurality of batteries at different combinations of three charging rates comprising: measuring means for measuring the voltage of each of said batteries and the temperature of each of said batteries; control means for determining whether the voltage of each of said batteries and the temperature of each of said batteries is within a predetermined region for applying a predetermined rate charge thereto; first charging means fo applying said predetermined current charge rate to each of asid batteries, said first charging means being externally controllable in response to said control means, for turning on and off said first charging means; second charging means for applying a further rate of charge to each of said batteries which is less than said predetermined current charge rate; first resistance means for initially limiting the charge from said further charging means to a first rate; second resistance means for subsequently limiting the charge from said further charging means to a second rate which is lower than said first rate; comparator means for detecting the voltage on each of said batteries and comparing it with a known reference voltage; and switching means for switching between said first and said second resistance means in response to the signal from said voltage comparator means whereby, for a fully discharged battery, the following sequence of charging rates is provided: (a) said first rate, (b) the combination of said first rate and said predetermined rate (c) the combination of said second rate and said predetermined rate, and (d) said second rate.

Claim 12

A battery charger system for charging each of a plurality of batteries at different combinations of three charging rates comprising: measuring means for measuring the voltage of each of said batteries and the temperature of each of said batteries; control means for determining whether the voltage of each of said batteries and the temperature of each of said batteries is within a predetermined region for applying a predetermined rate charge thereto; first charging means fo applying said predetermined current charge rate to each of asid batteries, said first charging means being externally controllable in response to said control means, for turning on and off said first charging means; second charging means for applying a further rate of charge to each of said batteries which is less than said predetermined current charge rate; first resistance means for initially limiting the charge from said further charging means to a first rate; second resistance means for subsequently limiting the charge from said further charging means to a second rate which is lower than said first rate; comparator means for detecting the voltage on each of said batteries and comparing it with a known reference voltage; and switching means for switching between said first and said second resistance means in response to the signal from said voltage comparator means whereby, for a fully discharged battery, the following sequence of charging rates is provided: (a) said first rate, (b) the combination of said first rate and said predetermined rate (c) the combination of said second rate and said predetermined rate, and (d) said second rate.

Claim 13

A high rate charging system for a battery comprising: means for monitoring the temperature of said battery; means for monitoring the voltage of said battery; first charging means for supplying a predetermined rate charge to said battery; control means for: (1) determining if said battery is in a predetermined condition for charging at said predetermined rate based on the temperature and voltage readings obtained from said means for monitoring temperature and voltage; (2) initiating and terminating the operation of said first charging means based on said temperature and voltage readings according to a predetermined control sequence; and (3) suspending said predetermined charging operation temporarily and monitoring said voltage reading only during said suspension; and bi-level rate further charging means for charging said battery even when said first charging means is not operating: (a) initially at a first rate and (b) subsequently at a second rate which is lower than said first rate so as to maintain full battery charge the following sequence of charging rates being provided for a fully discharged battery: (a) said first rate, (b) the combination of said first rate and said predetermined rate, (c) the combination of said second rate and said predetermined rate, and (d) said second rate.

Claim 14

A high rate charging system for a battery comprising: means for monitoring the temperature of said battery; means for monitoring the voltage of said battery; first charging means for supplying a predetermined rate charge to said battery; control means for: (1) determining if said battery is in a predetermined condition for charging at said predetermined rate based on the temperature and voltage readings obtained from said means for monitoring temperature and voltage; (2) initiating and terminating the operation of said first charging means based on said temperature and voltage readings according to a predetermined control sequence; and (3) suspending said predetermined charging operation temporarily and monitoring said voltage reading only during said suspension; and bi-level rate further charging means for charging said battery even when said first charging means is not operating: (a) initially at a first rate and (b) subsequently at a second rate which is lower than said first rate so as to maintain full battery charge the following sequence of charging rates being provided for a fully discharged battery: (a) said first rate, (b) the combination of said first rate and said predetermined rate, (c) the combination of said second rate and said predetermined rate, and (d) said second rate.

Claim 15

A system as in claim 9 wherein said control means further comprises (4) means for operating an indicator based on the temperature of said battery, said indicator being in one state when said battery is overheating, and a second state when said battery is too cold.

Claim 16

A system as in claim 10 wherein said one state is a steady state, and said second state is a "flashing" state.

Claim 19

A method as in claim 12 wherein said recurrently testing step comprises the steps of: (1) sensing the temperature of said battery and suppressing said second charging step if the temperature of said battery is a predetermined amount in excess of ambient temperature; (2) applying said second rapid rate charge at a predetermined duty cycle if the temperature of said battery is a predetermined amount less than ambient temperature; and (3) beginning said second rapid rate charge if said battery is within safe temperature limits.

Claim 20

A method as in claim 13 wherein said recurrently testing step further comprises the steps of: terminating said charging for a short predetermined time within a longer predetermined time period; and testing the terminal voltage at said battery during this short predetermined time.