Deactivating-battery-sensor

The sensing circuit quickly disconnects the battery voltage and load when the voltage falls below a predetermined threshold. The one-way operation ensures that the circuit does not reconnect the load if the voltage subsequently rises above the threshold. Component Cl prevents the circuit from activating during the connection to the battery; if the connections are accidentally reversed, Di will block the relay from turning on. After connecting the battery, no action occurs until pushbutton switch Sl is pressed, allowing relay Kl to energize. When Sl is released, the relay remains activated only if the battery voltage exceeds the minimum level. This threshold can be preset to 31.5 V for testing 36-V batteries using resistor R4. As the battery voltage decreases, Ql starts to turn off. Once the threshold is reached, Q2 also begins to turn off, and its increasing collector voltage provides positive feedback to the base of Ql, hastening its turn-off. When Q2 is fully off, the relay deactivates, disconnecting the battery from its load.

The described sensing circuit is a protective mechanism designed to ensure that a battery is not subjected to excessively low voltage conditions, which could lead to damage or reduced lifespan. The circuit employs a relay (Kl) to control the connection to the load, ensuring that power is only supplied when the battery voltage is above a safe operating level.

The operation begins with the connection of the battery, at which point no current flows until the user presses the pushbutton switch (Sl). This action energizes the relay (Kl), allowing current to flow to the load. The circuit is designed to maintain this state as long as the battery voltage remains above the preset threshold of 31.5 V, which can be adjusted through resistor R4.

As the battery discharges and the voltage approaches the threshold, transistor Ql begins to turn off. This transition is crucial because it initiates a feedback loop through Q2. When Ql starts to deactivate, the voltage at the collector of Q2 rises, providing positive feedback to the base of Ql, which accelerates its turn-off process. This rapid response is essential for protecting the battery from going below the critical voltage threshold.

Once Q2 turns off completely, the relay (Kl) is de-energized, which disconnects the load from the battery. This disconnection is a critical safety feature, preventing further discharge of the battery and potential damage. The use of diode Di ensures that even if the battery connections are reversed, the circuit will remain safe and not allow the relay to activate, thereby protecting the components from reverse polarity damage.

Overall, this sensing circuit is an effective solution for battery management, ensuring safe operation by disconnecting the load under low voltage conditions while providing a simple user interface through the pushbutton switch.The sensing circuit rapidly disconnects the battery voltage and load whenever the voltage drops below a preset threshold. One-way operation prevents the circuit from reconnecting the load if the voltage should then rise above the threshold.

Cl ensures that the circuit doesn"t activate while making connections to the battery; if you accidentally reverse these connections, Dl will block the turn on the relay. After you connect the battery, nothing happens until you depress pushbutton switch Sl, which allows relay Kl to energize.

When you release Sl, the relay remains on only if the battery voltage is above the minimum level. You preset this threshold-to 31.5 V when testing 36-V batteries, for example-using R4. Ql begins to turn off as the battery voltage drops. Once the threshold level is reached, Q2 also begins to turn off, and its rising collector voltage provides positive feedback to the base of Ql, accelerating the turn off. When Q2 turns off, the relay drops out, disconnecting the battery from its load. 🔗 External reference