Battery system and protection apparatus thereof

A battery system includes a battery and a battery protection apparatus. The battery protection apparatus protects the battery from over-discharge. The battery protection apparatus includes a voltage controlled switch, a start switch, and a voltage detecting unit. The voltage controlled switch establishes an electrical connection between the battery and the load. The start switch turns on the voltage controlled switch when actuated. The voltage detecting unit detects a battery voltage of the battery and generates a detecting voltage according to the battery voltage. The voltage controlled switch is turned off when the detecting voltage is lower than a predetermined value.

BACKGROUND

1. Technical Field

The present disclosure relates to batteries, and particularly to a rechargeable battery system and a battery protection apparatus.

2. Description of Related Art

Rechargeable batteries tend to over-discharge when used incorrectly. For example, when a battery has discharged to the manufacturer specification and power is still being drawn from the battery, over-discharge will be the result.

It is found that, over-discharge may cause damage to rechargeable batteries, especially at heavy current or repeated over-discharge. Commonly over-discharge raises the inner pressure of the rechargeable battery, and the reversibility of the rechargeable battery will be damaged. When recharging an over-charged battery the capacity of the rechargeable battery is reduced.

Therefore, a battery system and a battery protection apparatus for preventing the battery over-discharge is desired.

DETAILED DESCRIPTION

Referring to the FIGURE, a battery system100is configured for supplying electrical power to an electronic device200or other loads. In the embodiment, the battery system100supplies a direct current (DC) voltage to the electronic device200. The battery system100includes at least one battery Vcc and a battery protection apparatus10coupled to the at least one battery Vcc. In the embodiment, the battery Vcc is a rechargeable battery, such as a lithium-ion battery. The battery protection apparatus10is configured to protect the battery Vcc from over-discharge, so as to prevent the battery from damage caused by the over-discharge. The battery protection apparatus10is also configured to establish and discontinue an electrical connection between the battery Vcc and the electronic device200according to user inputs.

The battery protection apparatus10includes a first input terminal IN1, a second input terminal IN2, a start switch SW1, a voltage controlled switch SWv, a voltage detecting unit101, a first output terminal OUT1, a second output terminal OUT2, a stop switch SW2, and a diode D1.

The battery protection apparatus10receives a battery voltage supplied by the battery Vcc via the first input terminal IN1connecting to an anode of the battery Vcc and the second terminal IN2connecting to a cathode of the battery Vcc. The first and the second output terminals OUT1, OUT2supply the battery voltage processed by the battery protection apparatus10to the electronic device200. The second input terminal IN2is connected to the second output terminal OUT2.

The voltage controlled SWv is configured for establishing the electrical connection between the battery Vcc and the electronic device200. The start switch SW1is configured for closing (turn on) the voltage controlled switch SWv when actuated, thereby, establishing the electrical connection. The voltage detecting unit101is configured for detecting the battery voltage supplied from the battery Vcc after the start switch SW1is actuated, and generating a detected voltage according to the battery voltage. When the detecting voltage is lower than a predetermined value, the battery Vcc has over-discharged. In this case, the voltage detecting unit101outputs a signal to open (turn off) the voltage controlled switch SWv that the electrical connection is discontinued. The stop switch SW2is configured for opening the voltage controlled switch SW1to discontinue the electrical connection when actuated.

The start switch SW1is a normally open switch. The start switch SW1is connected between the first input terminal IN1and the voltage detecting unit101.

The voltage controlled switch SWv includes a relay J1and a bipolar junction transistor (BJT) Q1. The relay J1includes a relay coil L, and a normally open relay switch SWr. The relay switch SWr is connected between the first input terminal IN1and the first output terminal OUT1. One terminal of the relay coil L is connected to the first input terminal IN1, and the other terminal of the relay coil L is connected to the collector of the BJT Q1. The emitter of the BJT Q1is connected to the second input terminal IN2. The base of the BJT Q1is connected to the voltage detecting unit101. In other embodiments, a field effect transistor may replace the BJT Q1.

When the electronic device200needs to be turned off, the stop switch SW2is turned on. As a result, the base of the BJT Q1connects to the emitter of BJT Q1, and the BJT Q1is deactivated. The relay J1is powered off, the relay switch SWr is opened, and the battery Vcc and the electronic device200are disconnected. The battery Vcc does not supply the battery voltage to the electronic device200.

The stop switch SW2is also a normally open switch. The stop switch SW2is connected between the base and the emitter of the BJT Q1. The cathode of the diode D1is connected to the first input terminal IN1, and the anode of the diode D1is connected to the collector of the BJT Q1.

The voltage detecting unit101includes a first resistor R1, a second resistor R2, and a third resistor R3. One end of the second resistor R2is connected to the relay switch SWr and the first output terminal OUT1, and the other end of the second resistor R2is connected to the second input terminal IN2via the first resistor R1. One end of the third resistor R3is connected to the start switch SW1, and the other end of the third resistor R3is connected to a node N1located between the first and the second resistors R1, R2. The node N1between the first and second resistors R1, R2is also connected to the base of the BJT Q1.

In operation, when the start switch SW1is closed, a battery voltage is supplied from the battery Vcc to the base of the BJT Q1via the resistor R3, and the BJT Q1activated. As a result, the relay J1is triggered, and the relay switch SWr is closed. The battery voltage is supplied to the electronic device200and the voltage detecting unit101. The voltage detecting unit101generates the detected voltage based on the battery voltage, and supplies the detecting voltage to the base of the BJT Q1. When the detecting voltage is higher than the predetermined value, the battery Vcc has not over-discharged, and the BJT Q1remains in an on-state. When the detecting voltage is lower than the predetermined value, it is determined that the battery Vcc is over-discharged, and the BJT Q1is turned off. As a result, the relay is powered off, the relay switch SWr is opened, and the electrical connection between the battery Vcc and the electronic device200is discontinued. Thus, the battery Vcc is protected from over-discharge. Furthermore, the diode D1prevents damage to the relay J1, caused by transient high voltage applied to the relay J1.

When the electronic device200needs to be turned off, the stop switch SW2is switched off. As a result, the base of the BJT Q1connects to the emitter of BJT Q1, and the BJT Q1is deactivated. The relay J1is powered off, the relay switch SWr is opened, and the battery Vcc and the electronic device200are disconnected. The battery Vcc does not supply the battery voltage to the electronic device200.