3LED Battery Level Indicator Circuit

提出的3个LED电池电量指示器通常可用于通过3个不同的LED照明来监视12 V铅酸电池电荷水平。整个电路仅使用几个BJT，几个齐纳二极管，电阻和LED构建。

检查电池电压的不同方法

比重计可能是检查铅酸电池状况的最有效方法。另一方面，水文计具有多种缺点。因为它们是由玻璃制成的，所以它们很细腻，在开车时使用可能是危险的。

由于液滴和蒸气腐蚀了大多数金属和物质，因此在它们上持续的少量电池酸会构成存储问题。这些可能对车库有好处，但是证明其在房屋工作场所罕见使用的成本通常是不切实际的。

Measuring the voltage with load connected is yet another way to verify the battery's status. Under a typical functional load, a lead-acid car battery in an acceptable state of charge (Soc) will have a voltage level between 11.6 and 14.2 volts. When a battery's voltage level falls beneath 11.6 volts, its capacity is drastically reduced, and it discharges fast.

This situation might not allow to turn the starting motor for too long, most of the time! If the voltage on load, on the other hand, is more than 14.5 volts, the battery is completely charged! If it stays in this condition for an extended period of time while the car is being driven, the alternator-regulator system may go faulty, and the battery could well be destroyed due to overcharging.

There are several methods for确定电池电压。A digital panel meter arranged as a voltmeter might be used. However, their disadvantage is that they are approximately 10 times more expensive than a hydrometer!

Using a 'expanded-scale voltmeter' is another best option.

需要进行斜视练习，以在米面上显示11至15伏之间的电压范围，以0-16伏的校准。在0-30伏量表上，情况甚至更糟，这在当代的多项式上很常见。

尺度下端的尺寸为11伏的仪表，在秤的极端尺寸为16伏特，可实现完美的效果。结果，创造了“扩展尺度”一词。

However, you wouldn't want to be staring at a meter on the dashboard while driving in traffic. The voltage range in which your battery is most effective is just about 2 volts.

实际需要的是一种指示，表明只有一眼，不需要任何“分析”。这正是我们在这个项目中试图实现的目标。

Making a 3 LED Indicator

我们创建了一个简单的3 LED电池指示器电路，显示以下内容：

• Yellow indicates that the battery is 'low'.
• Green indicates that the battery is in good condition.
• Red indicates that the battery has been overcharged.

A yellow indicator illuminates when the battery voltage falls below 11.6 volts. This implies that the battery is either undercharged or that a large load (such as high-powered driving lights) is draining too much power.

When the voltage is between 11.7 and 14.2 volts, the green LED light turns on, indicating that everything is well. When the red indicator illuminates, which it would if the voltage exceeds 14.2 volts, the vehicle's voltage regulator may need to be adjusted, or there may be another issue.

Circuit Description

The working of this 3 LED battery indicator circuit is dependent on the varying voltage drops across the different color LEDs. The voltage drops across red, yellow, and green LEDs at 20 mA are generally 1.7V, 3.0V, and 2.3 volts. Q1 and Q2 are turned off by R3 and R5 when the vehicle battery voltage becomes extremely low for either ZD1/ZD2 or ZD3 to conduct.

在这些条件下，黄色LED是向前偏置的，并通过D1进行操作，在点A处产生约3.7伏的电压（请参见电路图）。ZD3一旦供应电压增加11.6伏，就开始进行ZD3，偏置Q2。绿色引导由于其低向前电压规格而产生照明，将点A的电压降低到2.6伏左右。

Because this isn't enough to turn on D1/LED3, the yellow LED turns off. The yellow LED's bias is 'stolen' by the green LED.

Q1 is biased on when the supply voltage exceeds 14.2 volts, and the red LED 'robs' the bias from the green LED. The red LED alone conducts when the voltage at point A drops to two volts.

电流通过LED受R1的限制。Q1碱电流受R2和R4的限制。

另一个简单的设计

Just three LEDs are utilized to indicate the battery state of the automobile (or boat). The LEDs are lit in the following manner:

D3 – 12 volts

12…13 V = D3 + D4

D4 = 13…14V

D4和D5 > 14 V

Preset P2 determines the voltage at which D3 turns off (13 V); PI determines the voltage at which D4 turns on (12 V); and P1 determines the voltage at which D5 turns on (13 V) (14 V). Because the different changes influence each other, the setting up procedure is very important and will need to be done multiple times. The author's prototype is shown in the image.