CHARGER FOR LITHIUM ION SECONDARY BATTERY, AND METHOD OF CHARGING THE SAME
First Claim
1. A charger for lithium ion secondary battery comprising:
- a series circuit of a reverse-current preventive switch, a charging switch and a current-detecting resistor, connected between a lithium ion secondary battery to be charged and the ground;
a charging control circuit controlling said reverse-current preventive switch and said charging switch, so as to make said lithium ion secondary battery repeat charging and opening at regular intervals, and so as to detect voltage difference between the specified voltage and the open circuit voltage of said lithium ion secondary battery during said opening; and
a constant-current/constant-voltage control circuit commanding constant-current charging at a first set voltage which is set relatively high in a range not exceeding the upper limit voltage of said lithium ion secondary battery, so far as said voltage difference does not exceed a predetermined change-over voltage difference, and commanding constant-voltage charging at a second set voltage, which is lowered from said first set voltage, when said voltage difference becomes smaller than said change-over voltage difference.
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Accused Products
Abstract
A charger for a lithium ion secondary battery includes a series circuit of a reverse-current preventive switch, a charging switch and a current-detecting resistor, connected between the battery and the ground a charging control circuit controlling the reverse-current preventive switch and the charging switch, so as to make the battery repeat charging and opening at regular intervals, and so as to detect voltage difference between the specified voltage and the open circuit voltage of the battery during the opening; and a constant-current/constant-voltage control circuit commanding constant-current charging at a first set voltage set relatively high in a range not exceeding the upper limit voltage of the battery, so far as the voltage difference does not exceed a predetermined change-over voltage difference, and commanding constant-voltage charging at a second set voltage, which is lowered from the first set voltage, when the voltage difference becomes smaller than the change-over voltage difference.
19 Citations
6 Claims
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1. A charger for lithium ion secondary battery comprising:
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a series circuit of a reverse-current preventive switch, a charging switch and a current-detecting resistor, connected between a lithium ion secondary battery to be charged and the ground; a charging control circuit controlling said reverse-current preventive switch and said charging switch, so as to make said lithium ion secondary battery repeat charging and opening at regular intervals, and so as to detect voltage difference between the specified voltage and the open circuit voltage of said lithium ion secondary battery during said opening; and a constant-current/constant-voltage control circuit commanding constant-current charging at a first set voltage which is set relatively high in a range not exceeding the upper limit voltage of said lithium ion secondary battery, so far as said voltage difference does not exceed a predetermined change-over voltage difference, and commanding constant-voltage charging at a second set voltage, which is lowered from said first set voltage, when said voltage difference becomes smaller than said change-over voltage difference. - View Dependent Claims (2, 3, 4)
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5. A method of charging a lithium ion secondary battery for repeating charging and opening of the lithium ion secondary battery at regular intervals, the method comprising the steps of:
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detecting voltage difference between the specified voltage and the open circuit voltage of said lithium ion secondary battery during said opening; performing constant-current charging at a first set voltage which is set relatively high in a range not exceeding the upper limit voltage of said lithium ion secondary battery, so far as said voltage difference does not exceed a predetermined change-over voltage difference; performing constant-voltage charging at a second set voltage, which is lowered from said first set voltage, when said voltage difference becomes smaller than said change-over voltage difference; and terminating the charging when said voltage difference becomes smaller than said predetermined change-over voltage difference. - View Dependent Claims (6)
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Specification