Overvoltage and overcurrent charging protection device and lead-acid battery charging circuit

Abstract

The invention discloses an over-voltage and over-current charging protection device and a lead-acid battery charging circuit. A control module in the device charges when a first controllable switch module is switched off and the output end of a charging power supply is not over-voltage and over-current, and controls the first controllable switch module to be switched on after charging is finished; therefore, the charging power supply can charge the battery in a delayed manner. And when the first controllable switch module is switched on and the output end of the charging power supply is over-voltage and / or over-current, discharging is carried out, and after discharging is finished, the first controllable switch module is controlled to be switched off, so that delayed power-off of the battery by the charging power supply is realized. According to the scheme, for the conditions that the output voltage of the charging power supply fluctuates at a critical point, the output voltage fluctuates greatly due to damage of the charging power supply and the output current of the charging power supply is over-current, on the premise that charging protection of the battery is guaranteed, frequent switching-on and switching-off of the first controllable switch module are avoided through the time-delay processing, and the service life of the first controllable switch module is prolonged. And the practicability and the stability of the overvoltage and overcurrent charging protection device are enhanced.

Description

Technical field [0001] The present invention relates to the field of circuit protection, and more particularly to an overvoltage overflow charge protection device and a lead-acid battery charging circuit. Background technique [0002] Lead-acid batteries still occupy a considerable share market as a battery with low price and high-quality batteries. For the charging of the lead-acid battery, the following method is usually used in the prior art: one is to charge it directly to the charger or DC power supply, but the technical indicator of the charger and DC power supply is uneven, if in use, the charger is used in use When the DC power source is selected or when it is damaged, there is no corresponding protection circuit in this method, it is easy to perform long-term overvoltage or overflow charging for a lead-acid battery, which seriously affects the use of lead-acid batteries. life. [0003] The second method is to add a charging protection circuit on the charging circuit of t...

AI Technical Summary

Problems solved by technology

However, there are many problems in this method. One is that when the charging voltage fluctuates at the overvoltage critical point or the charger is damaged, the output voltage fluctuates greatly, and the comparator A1 will respond immediately to control the switch tube Q to be turned on and off. , this frequent action causes frequent charging of the lead-acid battery, and when the output current is large, the switching tube Q will generate a large switching loss, which is likely to be thermally broken down; When the output current is overcurrent, the comparator A2 will respond immediately to control the switch tube Q to be turned on and off. This frequent action also causes frequent charging of the lead-acid battery. At the same time, when the output current is large, the switch tube Q will Generates large switching losses and is likely to be thermally broken down

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