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 of the battery should not be allowed, since this reduces the density and, accordingly, increases the freezing temperature of the electrolyte.

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 of the 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 operating principle of the controller is as follows: as long as 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.

“After charging the battery, the indicator on the lid began to glow white - what should I do?”

Charge indicator battery- What is this? How is it built?

This is a simple hydrometer. A lens and a ball in a tube that changes its position under the influence of an electrolyte. When the electrolyte density is 1.27-1.29 (the battery is charged), the ball floats to the very top and occupies the center visible through the lens. In this case, we see the lens as completely green (green with stripes, other options). When the battery is discharged, the density of the electrolyte decreases, the float ball begins to fall and the lens turns black (turns red or changes color to another).

The ball is lowered to the lowest position if the electrolyte level has become too low and the ball is in the air. In this case, the indicator signals the need to add distilled water to the battery.

The color designation of the eye indicator states is usually reflected in a legend printed next to it on the label.

For example, it could be like this:
Green - full charge;
White - the battery needs to be recharged;
Red with a black dot - the battery is completely discharged;
Red - add water.

Unfortunately, the indicators are designed in such a way that they allow a very rough estimate of the density of the electrolyte. It is impossible to find out exactly the percentage of battery charge using such an indicator. It only detects a complete discharge, and then only in one of the six battery cells. A 50% discharged or fully charged battery is no different for the eye indicator.

By and large, this is a toy. But many manufacturers introduce it into the design, since the absence of a peephole is perceived by most consumers as a disadvantage.

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Most modern car batteries from manufacturers are equipped with built-in battery charge indicator eyes. You can also purchase a battery in which the peephole is not built-in, but removable and screwed in instead of one of the six plugs. Some motorists believe that there is a light bulb installed there, but they are mistaken. The principle of the car battery eye is more like a float that shows 3 battery states. Let's look at each one separately.

Battery eye green

This indicator color indicates that the battery is OK. The density of the electrolyte is higher than 12.5, so the lighter indicator ball, which is green, fits closely to the eye.

Indicator eye red

The red color of the battery charge indicator means that the density of the battery has dropped below 12.5, the indicator ball has sunk in the electrolyte and the electrolyte allows the red color to pass through the eye, which is located at the bottom of the indicator.

Indicator eye white or black

Typically, these colors mean that the ball is at the very bottom of the indicator due to low electrolyte levels. And since the indicator itself is located outside the electrolyte (which is a light conductor for the indicator), you cannot see the red color of the bottom of the indicator.

Please note that some battery manufacturers have a different color indicator from the examples given in the article. For example, for Aktech and Zver batteries, a red indicator indicates a low electrolyte level, and a black indicator indicates a low battery discharge.

All about batteries

A battery is a chemical source of current, for which certain chemical processes must occur to function properly. As the battery discharges, sulfuric acid “sticks” to the negative electrode, forming insoluble lead sulfate, leaving

Very often you can hear recommendations about hybrid batteries from salespeople in car dealerships. So what is a hybrid battery? A hybrid battery for a car is externally indistinguishable from other acid batteries, except for the ethical designation

Every motorist sooner or later becomes interested in the design of a car battery and the principle of its operation. A car battery serves as the heart of any modern car - thanks to it we start the engine, listen to music in the car.

Guest

To make it easier to visually determine the operating condition of the battery, there are special indicators on it. (By the way, the appearance of the indicator is somewhat similar to a hydrometer). The indicator displays the state inside the container in one of three colors: green – everything is fine, black – urgently charge, white – “Bobby is dead”. Everything seems to be in order: after all, convenience is obvious! By the way, in the past it was necessary to unscrew the caps of “cans” quite often in order to see the condition inside the container. Today everything is much simpler. But many car owners have one question: how accurate is the “diagnosis” of the indicator? Could he be wrong? Well, let's watch. So!

Unfortunately, the indicator cannot accurately display the full depth of the battery condition. Example: you see your indicator - it shows green. Everything seems to be fine, right? But there is a nuance: your indicator will be green both at a charge level of 100% and at 60%. Did you feel the difference? 40% difference is a bit much, but the indicator is in no hurry to tell you about it. On the one hand, there is nothing strange here, since even with such a charge, your car will start normally. True, only in very warm seasons. What if it’s winter outside? Does the indicator show that everything is ok? Did you know that in winter the engine may not start even with a 75% battery charge - where does 60% compare? It turns out to be a paradox: even a half-dead battery will show that everything is in order. But this would not be so bad if it were not for such a thing as cranking at startup: even an experienced “driver” does not always understand that cranking is a consequence of insufficient battery power and often mistakes it for a defective starter.

As a matter of fact, if you simply take into account such points as the density of the electrolyte and the air temperature, then we can say the following: the indicator is not an accurate indicator of the actual state of the battery capacity! What do density and temperature have to do with it? And despite the fact that the density of the electrolyte decreases depending on the air temperature!

However, if your indicator shows you a “white card” (that is, white), then further use of the battery should be stopped immediately! Why? The battery can explode, and in the most literal sense of the word. An explosive mixture of hydrogen and oxygen forms in the container of a “dead” battery. The slightest spark and - “momento more” (instantly in the sea).

Finally, one more point: the indicator shows the status of only one battery cell – in which it is built! Thus, this is another factor that indicates the failure of this “device”.

In general, comrades, an indicator is an indicator, but it is better to use proven methods of checking the battery - with special devices. But more on this in the next article. Good luck!

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 set. 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 of the printed circuit board: 43 by 20 millimeters.