Charger Circuit Low Current Control Timer
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Solution Overview
Problem
Existing charger circuits incorrectly determine a battery as dead if it is charged at a low rate, failing to continue charging usable batteries after a predetermined maximum charging period is reached.
Innovation Solution
A charger circuit that maintains a low charging current after the maximum charging period, using a timer and oscillator to dynamically track the charging period and switch to a low current control mode, allowing continued charging of batteries that would otherwise be deemed dead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charging current is stopped when a predetermined maximum charging period is reached, then the charger avoids charging dead batteries indefinitely, but usable batteries charged at low rates are incorrectly determined as dead
Solution Approach 1:
The charging system dynamically adjusts the charging current based on the charging period. After the maximum charging period is reached, the system transitions from normal charging current to a lower maintenance current, allowing continuous charging of usable batteries while still limiting charging of dead batteries. This dynamic adjustment resolves the contradiction by adapting the charging behavior to different battery states.
Solution Approach 2:
The patent changes the charging current parameter from normal level to a lower level after the maximum charging period is reached. This parameter change allows the system to continue charging batteries that are still usable (providing a low current to maintain functionality) while effectively limiting charging of dead batteries (where the low current is insufficient to revive them).
2Loss of time
If the charging current is stopped after maximum charging period, then the charger prevents infinite charging of dead batteries, but fails to charge usable batteries with low charging rates
Solution Approach 1:
The charging system implements periodic action by switching from normal charging current to lower maintenance current after the maximum charging period. This periodic modulation of charging intensity allows the system to respect the time constraint (maximum charging period) while maintaining charging effectiveness for usable batteries through the lower current continuation.
Solution Approach 2:
The patent maintains continuity of useful action by keeping the charging current flowing at a reduced level after the maximum charging period. This continuous low-level charging ensures that usable batteries continue to receive charge (maintaining their functionality) while the overall charging process remains time-limited, preventing infinite charging of dead batteries.
3Productivity
If a timer stops charging at maximum period, then the charger limits charging duration, but misclassifies usable low-rate batteries as dead
Solution Approach 1:
The system dynamically adjusts charging current based on timing information, transitioning from normal current to maintenance current after the maximum period. This dynamic response maintains charging efficiency by continuing to charge usable batteries at a reduced rate while preventing waste on dead batteries, thereby improving reliability of battery status determination.
Solution Approach 2:
The charging current parameter is changed from normal level to maintenance level after the maximum charging period. This parameter change allows the system to maintain productive charging of usable batteries (at lower current) while reliably identifying and limiting charging of dead batteries, thus resolving the contradiction between productivity and reliability.
Data Source
AI summary
A charger circuit comprising: a charging path coupled between an input voltage and a battery; a power switch on the charging path; a switch control circuit controlling the power switch; a timer counting a charging period; and a low current control circuit issuing a signal to the switch control circuit to control the power switch such that a charging current is maintained to be a predetermined low current when the timer counts to a predetermined maximum charging period.