Author ：Iflowpower – Portable Power Station Supplier
The commercial emergency light has over-conservation function, but there is often no discharge protection. If the battery is excessively discharged, the sulfate crystals will be made larger, which not only adds the electrical resistance of the plate, but it is difficult to make it restore during charging, directly affect the capacity and life of the battery. The circuit supplied here can protect the battery from overcharge and over-discharge.
When the AC power is active, the load powers from the regulator; if the AC power is invalid, the load is automatically transferred to the 6V battery. When the AC power is restored, the load returns to power by the regulator, and the battery starts charging. The entire circuit can be divided into four parts: power supply, switching circuit, excessive discharge protection circuit and overcharge protection circuit.
The AC power supply of the power supply passes through the transformer X1 buck, the bridge rectifier BR1 is rectified, and the capacitor C1 is filtered, and the chip 7806 (IC1) is stabilized into a 6V power supply. The switching circuit consists of transistor T1 and relay RL1 components. When the AC power is active, T1 is turned on, so that RL1 (6V, 100Ω) is absorbed, green LED1 illuminates, indicates that AC power is effective.
At the same time, the regulator outputs the normally closed contact N / C and RL3 of the RL1 to connect to the load, while the 6V battery is charged via the normally closed contact N / C of RL2. T1 is closed when the AC power is invalid. RL1 release.
Results The load changes from the normally closed contact N / C of RL1 from the 6V battery, at which time the LED1 is off, indicating that the AC power is not existed. The excessive discharge protection circuit of the battery consists of IC3, T3, RL3 and other components. When the battery is excessively discharged (less than 5.
5V), the voltage on the IC3 inverted input (2) is higher than the voltage on its homogenic input (3), and the IC3 output is low, T3 is turned on, RL3 (5V, 100Ω, the load is disconnected from the 6V battery due to the contact N / C separation, thereby preventing over-discharge. At the same time, LED3 illuminates, indicating that the battery is over-discharged. When the AC power is restored, the battery is charged by RJ2 contact N / C.
When the battery voltage reaches 5.5V. The output of the IC3 returns to a high potential.
T3 is closed, RL3 is released, and the load is connected to the output of the regulator. Excessive charging protection circuit of the battery consists of IC2, T2, RL2 and other components. When the AC power is valid, and the battery voltage is below 6.
6V. Since the voltage on the IC2 inverting input 2 is higher than the voltage on the same phase input 3, the output of the IC2 is low, T2 is closed, and the RL2 (6V.100Ω) remains in the release state.
At this time, the battery is continuously charged through the N / C contact of RL2. Once the battery voltage reaches 6.6V.
The output of IC2 is high, T2 is turned on, RJ2 is absorbed, and charging is stopped. At this time, LED2 illuminates, indicating that the battery is over-charging. In the drawings, D2, D3 protects RL2, RL3 from the impact of the anti-electromotive force.
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