Battery charging method and apparatus
First Claim
1. A gas point detection method for use in charging a battery that reaches a gassing point while being charged comprising the steps of:
- (a) measuring a charge voltage;
(b) waiting a predetermined amount of time;
(c) measuring a second charge voltage; and
(d) comparing the first voltage to the second voltage and determining a gassing phase to be a predetermined amount of voltage difference over the predetermined time period.
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Accused Products
Abstract
A battery charger employing the gassing point of a lead-acid battery to determine the end of charge time and voltage. A charging level sensor takes two voltage samples of a predetermined time period to determine the change in voltage rate. If the change in voltage rate exceeds a predetermined amount the batteries are considered to be gassing. The batteries are further charged for a predetermined amount of time after the gassing phase has been entered. The invention provides a load management control function to provide a safe DC charge voltage when a hall effect sensor senses a DC load. The charger is cut off if a house load is used while the battery is being charged. The charging circuit achieves different end of charge voltages depending on a user selected battery type. The battery charger is a constant voltage temperature compensated current limited charger.
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Citations
18 Claims
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1. A gas point detection method for use in charging a battery that reaches a gassing point while being charged comprising the steps of:
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(a) measuring a charge voltage; (b) waiting a predetermined amount of time; (c) measuring a second charge voltage; and (d) comparing the first voltage to the second voltage and determining a gassing phase to be a predetermined amount of voltage difference over the predetermined time period. - View Dependent Claims (2, 3)
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4. A charging method for a battery that gasses while being charged by a battery charger including a gas point detector circuit, a charging circuit and an overcharge timer, the method comprising the steps of:
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(a) turning the battery charger on to supply charge current to the battery; (b) measuring the charging current; (c) continuing to measure the charge current until the charge current is less than a predetermined amount; (d) turning the charger off; (e) enabling the gas point detector circuit; (f) waiting a first predetermined amount of time for the charge circuit to reach quiescence; (g) taking a first voltage sample from the charging circuit; (h) waiting a second predetermined amount of time; (i) taking a second voltage sample; (j) comparing the first voltage sample to the second voltage sample and if the difference between the two voltages is greater than a predetermined reference voltage then determining that the gas point has been reached; (k) disabling the gas point detector circuit; (l) resetting the overcharge timer to a predetermined starting time; (m) starting the overcharge timer and waiting until the overcharge timer times out after a predetermined overcharge timer time period; and (n) turning off the charger when the overcharge timer times out. - View Dependent Claims (5)
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6. A gas point detection apparatus for detecting the gassing point of a battery having battery terminals, the apparatus comprising:
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(a) a first sample and hold connected at a first input to a first battery terminal to sample the battery voltage at a first time; (b) a second sample and hold connected at a first input to the first battery terminal to sample the battery voltage at a second time; (c) a first comparator to compare the voltage of the first sample and hold from the second sample and hold having a voltage difference output; and (d) a second comparator connected to the voltage difference output, wherein the second comparator compares the voltage difference output to a predetermined reference voltage and the second comparator has a gas point detector output. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification