A battery charge indicator is a necessary thing in the household of any motorist. The relevance of such a device increases many times over when, for some reason, a car refuses to start on a cold winter morning. In this situation, it’s worth deciding whether to call a friend to come and help you start from your battery, or whether the battery has died for a long time, having discharged below a critical level.

Why monitor your battery's condition?

A car battery consists of six batteries connected in series with a supply voltage of 2.1 - 2.16V. Normally, the battery should produce 13 - 13.5V. Significant discharge should not be allowed battery, since in this case the density decreases and, accordingly, the freezing temperature of the electrolyte increases.

The higher the battery wear, the less time it holds a charge. In the warm season, this is not critical, but in winter, side lights forgotten while turned on can completely “kill” the battery by the time it is returned, turning the contents into a piece of ice.

In the table you can see the freezing temperature of the electrolyte, depending on the degree of charge of the unit.

Dependence of the freezing temperature of the electrolyte on the state of charge of the battery
Electrolyte density, mg/cm. cube	Voltage, V (no load)	Voltage, V (with load 100 A)	Battery charge level, %	Electrolyte freezing temperature, gr. Celsius
1110	11,7	8,4	0,0	-7
1130	11,8	8,7	10,0	-9
1140	11,9	8,8	20,0	-11
1150	11,9	9,0	25,0	-13
1160	12,0	9,1	30,0	-14
1180	12,1	9,5	45,0	-18
1190	12,2	9,6	50,0	-24
1210	12,3	9,9	60,0	-32
1220	12,4	10,1	70,0	-37
1230	12,4	10,2	75,0	-42
1240	12,5	10,3	80,0	-46
1270	12,7	10,8	100,0	-60

A drop in charge level below 70% is considered critical. All automotive electrical appliances consume current, not voltage. Without load, even a severely discharged battery can show normal voltage. But at a low level, during engine startup, a strong voltage drop will be noted, which is an alarming signal.

It is possible to notice an approaching disaster in a timely manner only if an indicator is installed directly in the cabin. If, while the car is running, it constantly signals about discharge, it’s time to go to the service station.

What indicators exist

Many batteries, especially maintenance-free ones, have a built-in sensor (hygrometer), the operating principle of which is based on measuring the density of the electrolyte.

This sensor monitors the condition of the electrolyte and the relative value of its indicators. It is not very convenient to climb under the hood of a car several times to check the condition of the electrolyte in different operating modes.

Electronic devices are much more convenient for monitoring the condition of the battery.

Types of battery charge indicators

Automotive stores sell many of these devices, differing in design and functionality. Factory devices are conventionally divided into several types.

By connection method:

• to the cigarette lighter socket;
• to the on-board network.

By signal display method:

• analog;
• digital.

The principle of operation is the same, determining the battery charge level and displaying information in a visual form.

Schematic diagram indicator

How to make a battery charge indicator using LEDs?

There are dozens of different control schemes, but they produce identical results. It is possible to assemble such a device yourself from scrap materials. The choice of circuit and components depends solely on your capabilities, imagination and the assortment of the nearest radio store.

Here is a diagram to understand how the LED battery charge indicator works. This portable model can be assembled “on your knee” in a few minutes.

D809– a 9V zener diode limits the voltage on the LEDs, and the differentiator itself is assembled on three resistors. This LED indicator is triggered by current in the circuit. At a voltage of 14V and above, the current is sufficient to light up all the LEDs; at a voltage of 12-13.5V they light up VD2 And VD3, below 12V - VD1.

A more advanced option with a minimum of parts can be assembled using a budget voltage indicator - chip AN6884 (KA2284).

Circuit of LED battery charge level indicator on voltage comparator

The circuit operates on the principle of a comparator. VD1– a 7.6V zener diode, it serves as a reference voltage source. R1– voltage divider. During the initial setup, it is set to such a position that all LEDs light up at a voltage of 14V. The voltage supplied to inputs 8 and 9 is compared through a comparator, and the result is decoded into 5 levels, lighting the corresponding LEDs.

Battery charging controller

To monitor the condition of the battery while the charger is operating, we make a battery charge controller. The device circuit and components used are as accessible as possible, while at the same time providing complete control over the battery recharging process.

The principle of operation of the controller is as follows: while the voltage on the battery is below the charging voltage, the green LED lights up. As soon as the voltage is equal, the transistor opens, lighting up the red LED. Changing the resistor in front of the base of the transistor changes the voltage level required to turn on the transistor.

This is a universal monitoring circuit that can be used for both high-power car batteries and miniature lithium batteries.

In modern practice, there are still cars that do not have an on-board computer or a display with a battery charge indicator. Driving without an indicator may result in the engine stopping completely and making it impossible to start it in the future.

The battery charge indicator performs two functions: it shows the charging current of the battery from the generator and informatively the amount of charge of the battery. There are several ways to fix this problem in a car. One of them is the simplest, making a device with your own hands to indicate battery charging.

Available sources contain many proposals for manufacturing a digital current circuit for such a device. It has a fairly simple appearance. To do this, you need skills in soldering radio components and the desire to assemble the device with your own hands. Select LED, Zener diode, breadboard and resistors. The diagram of the battery charge indicator is shown in the figure below.

Operating principle

The LED indicator, thanks to the presence of three LED colors, can show different phases of charging current. Start of charging. Working middle. Process end warning. This circuit gives us the ability to control the entire operating cycle of the battery.

It’s not difficult to solder the parts yourself, but first check with a tester. If all the parts are in good order, you can make the assembly according to the diagram. The tester's nickname is LED output. We determine the low voltage output from six to eleven volts.

This is a red LED. From eleven to thirteen volts – yellow. More than thirteen - there will be a green LED. The circuit has a simple set of parts and works reliably.

Interesting! The battery supplies a certain voltage to the LED. It lights up. This is how we determine the beginning and end of battery charging.

If you don’t have any components, then you need to look at similar diagrams on the Internet and modify the device yourself. The circuit will also reliably show the battery current charge indication.

For a car, it is important that the circuit does not work all the time, but only when the driver is behind the wheel. It is recommended that after finishing the work with your own hands, you mount the resulting device under the steering wheel and connect it to the ignition switch. In this case, the indicator will only work when the car ignition is turned on.

We see that after finishing the work, you can create a battery charge indicator that is convenient and necessary for reliable operation of the car with your own hands. The cost of such a product will not be high.

Important! The reliability of the indicator and the convenience of its placement make it possible to effectively eliminate the imperfections of designers and car manufacturers.

On the one hand, any device, be it a vehicle or a simple kitchen utensil, seems perfect and refined from a technical point of view. Does not require the intervention of human thought and competent hands.

On the other hand, there will always be competent “Kulibins” for whom this device seems imperfect and requires improvement and technical refinement.

Progressive technical progress is built on this. A seemingly simple, but at the same time vitally important visual indication of the process of charging a car battery, not designed by designers, found its simple development by simple admirers of the world of science and technology.

Today we will make a simple design to help any car enthusiast. Every driver is familiar with the situation when car battery discharged at the most inconvenient moment and to guard against such cases, you need charge indicator and control car battery . Such a controller has Three built-in LED indicators - yellow, green and red.

Due to its compact size circuit board, the controller circuit can be carefully adjusted on the control panel or somewhere in the front board; in general, you need to act according to the circumstances, being guided by the features of the control panel of your car.

The device is implemented on just one chip and is powered directly from the on-board 12 Volt network.

The device itself was assembled at the request of a friend who complained about low level battery charge. The entire process is monitored by a microcircuit that works very accurately.
Zener diode - any one will do, domestic or imported, for any power. The main thing is to choose a zener diode with a stabilization voltage of 5.6 Volts. Of the most common zener diodes, KS156A, BZX55C5V6, BZX79-C5V6, BZX88C5V6 and others are excellent.

As we know, tension in the on-board network when the car is running, it does not exceed 14.4 Volts, and the voltage of the battery itself is 12-13 Volts. When everything is normal, that is, the voltage is normal, the green LED of the controller lights up, when it is above the normal limits, the red one lights up, and when the voltage on the battery is below 12 Volts, the yellow LED lights up.

When the car is running very rarely the red LED may light up, don’t worry - this is normal! When the yellow LED is on, the battery needs to be charged, but who doesn’t? chargers, no problem! On our website we have provided a huge number of charger circuits for every taste!

Regarding the housing for the indicator, I think that if you adapt the device, say, under a board, then there is no need for a housing, just fix the board with silicone or hot glue and the device will serve you faithfully for a long time.

The quality of battery charging determines how successfully the car will start. Not many drivers monitor the battery charge level. The article discusses such a useful device as a car battery charge indicator: how it works, how it works, instructions and a video on how to make it yourself.

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Characteristics of the battery charge level indicator

On modern cars with an on-board computer, the driver has the opportunity to obtain information about the level. Older models are equipped with analog voltmeters, but they do not reflect the true picture of the battery's condition. Battery voltage indicator (VIN) is an option to have operational information about the battery voltage.

Purpose and device

The IN is assigned two functions - to show how the battery is charged from the generator, and to inform about the amount of charge of the car battery. The easiest way is to assemble such a device with your own hands. Scheme homemade device simple. Having purchased the necessary parts, it is easy to assemble the indicator with your own hands. This way you can save money, since the cost of the device is low (the author of the video is AKA KASYAN).

Operating principle

The charge level indicator has three LED lights of different colors. Usually these are: red, green and blue. Each color has its own informative meaning. Red color means low charge, which is critical. Blue corresponds to the operating mode. Green color indicates the battery is fully charged.

Varieties

IN can be placed on batteries in the form of a hydrometer or in the form of separate devices with an information display. Built-in IDs are usually placed on. They are equipped with a float indicator (hydrometer). He has simple design.

Factory identification numbers are available:

1. DC-12 V. The device is a construction set. With its help, you can monitor the charge of the battery and the performance of the relay regulator.
2. For those whose car is equipped with a second battery, a panel with an indicator from TMC will be a useful device. This is an aluminum panel with a voltmeter placed on it and a switch from one battery to another.
3. ID Signature Gold Style and Faria Euro Black Style - determine the battery charge level. But their cost is too high, so there is little demand for them.

Guide to making a device at home

The simplest and cheapest option is a self-made IN. Its purpose is to control how the battery operates when the voltage in the on-board network is within the range of 6-14V.

To prevent the device from working constantly, it should be connected through the ignition switch. In this case it will work when the key is inserted.

The following parts will be needed for the diagram:

• PCB;
• resistors: 2 with a resistance of 1 kOhm, 1 with a resistance of 2 kOhm and 3 with a resistance of 220 Ohm;
• transistors: VS547 - 1 and VS557 - 1;
• Zener diodes: one for 9.1 V, one for 10 V;
• LED bulbs (RGB): red, blue, green.

For LEDs, using a tester, you need to determine and check the pins so that they match the color. The device is assembled according to the diagram.

The components are tried on the board and cut to the appropriate sizes. It is advisable to arrange the components so that they take up less space.

It is better to solder LEDs to wires rather than to a board, so that the indicators can be more conveniently placed on the dashboard.

Based on the manufactured device, it is impossible to determine specific battery voltage values; you can only navigate within what limits it is located:

• red lights up if the voltage is from 6 to 11 V;
• blue corresponds to voltage from 11 to 13 V;
• Green means fully charged, meaning the voltage is greater than 13V.

The battery voltage indicator can be installed anywhere in the cabin. It is most convenient to place it at the bottom of the steering column: the LEDs will be clearly visible and will not interfere with control. In addition, the device can be easily connected to the ignition switch. After installation, the driver will be able to always know how charged his car’s battery is and charge his battery if necessary.

What are the car battery charge indicators?

The battery plays a key role in starting a car engine. And how successful this launch will be largely depends on the state of charge of the battery. How many of us monitor the battery charge level? It’s called, answer this question for yourself. Therefore, there is a high probability that one day you will not start your car due to a dead battery. Actually, checking the state of charge itself is not difficult. You just need to periodically measure with a multimeter or voltmeter. But it would be much more convenient to have a simple indicator showing the battery charge status. Such indicators will be discussed in this material.

Technology does not stand still and automotive manufacturers are trying their best to make car travel and maintenance as comfortable as possible. Therefore, on modern cars in the on-board computer, among other functions, you can find data on the battery voltage. But not all cars have such capabilities. Older cars may have an analog voltmeter, which makes it quite difficult to understand the condition of the battery. For beginners in the automotive business, we advise you to read the material about.

Therefore, all kinds of battery charge indicators began to appear. They began to be made both on batteries in the form of hydrometers and additional information displays on the car.

Such charge indicators are also produced by third-party manufacturers. They are quite easy to place somewhere in the cabin and connect to the on-board network. In addition, on the Internet there are simple schemes for making charge indicators with your own hands.

Built-in battery charge indicator

Built-in charge indicators can be found mainly on. This is a float indicator, which is also called a hydrometer. Let's see what it consists of and how it works. In the photo below you can see how this indicator looks on the battery case.

And this is what it looks like when you take it out of the battery.

The structure of the built-in battery indicator can be schematically represented as follows.

The operating principle of most hydrometers is as follows. The indicator can show three different positions in the following situations:

• As the battery charges, the density of the electrolyte increases. In this case, a float in the shape of a green ball rises up the tube and becomes visible through the light guide into the indicator eye. Typically, the green ball floats up when the battery charge level is 65 percent or higher;
• If the ball sinks in the electrolyte, it means the density is below normal and the battery charge is insufficient. At this moment, a black indicator tube will be visible through the “eye” of the indicator. This will indicate the need to charge. Some models add a red ball that rises up the tube at a reduced density. Then the “eye” of the indicator will be red;
• And another option is to lower the electrolyte level. Then the surface of the electrolyte will be visible through the “eye” of the indicator. This will indicate the need to add distilled water. However, in the case of a maintenance-free battery, this will be problematic.

This built-in indicator allows you to make a preliminary assessment of the battery charge level. You should not rely entirely on the hydrometer readings. If you read numerous reviews about the operation of these devices, it becomes clear that they often show inaccurate data and quickly fail. And there are several reasons for this:

• The indicator is installed in only one of the six battery cells. This means that you will have data on density and degree of charge for only one jar. Since there is no communication between them, one can only guess about the situation in other banks. For example, in this cell the electrolyte level may be normal, but in some others it may be insufficient. After all, the evaporation of water from the electrolyte differs among the banks (in the extreme banks this process is more intense);
• The indicator is made of glass and plastic. Plastic parts may warp when heated or cooled. As a result, you will see distorted data;
• The density of the electrolyte depends on its temperature. The hydrometer does not take this into account in its readings. For example, on a cold electrolyte it may show normal density, although it is reduced.

Factory battery charge indicators

Today on sale you can find quite interesting devices for monitoring the battery charge level by its voltage. Let's look at some of them.

Battery charge level indicator DC-12 V

This device is sold as a construction kit. It is suitable for those who are familiar with electrical engineering and a soldering iron.

The DC-12 V indicator allows you to check the charge of the car battery and the functioning of the relay regulator. The indicator is sold as a set of spare parts and can be assembled independently. The cost of a DC-12 V device is 300-400 rubles.

Main characteristics of the DC-12 V indicator:

• Voltage range: 2.5─18 volts;
• Maximum current consumption: up to 20 mA;
• Dimensions printed circuit board: 43 by 20 millimeters.