The density of the electrolyte in the battery - when does a car owner become a chemist? Hydrometer: principle of operation and known varieties Purpose and rules for working with a hydrometer

Surely every car owner has encountered the problem of a bad start vehicle in winter time. There may be several reasons for this. But in most cases, the battery is the culprit. The fact is that key feature its performance is the density of the electrolyte. The battery charge, its voltage and the quality of the engine start depend on this parameter. Periodically it is recommended to check the density of this liquid. For this, a special measuring tool. In today's article, we will look at what a hydrometer is, and also learn how to correctly measure the density of the electrolyte in the battery and antifreeze in the cooling system. This information will be useful to every car owner.

Characteristic

So what is a hydrometer? This is an instrument that serves to measure the density of solids and liquids. The principle of operation of the hydrometer is based on the law of Archimedes. Externally, this device is glass flask, the lower part of which is filled with shot to obtain the desired mass.

At the top (in the narrow part of the tube) there is a scale. It is graduated according to the density of the solution. At the moment, there are two types of hydrometers - constant mass and constant volume.

How it works?

This device operates thanks to a special float. It is he who determines exact density liquids. How to use a battery hydrometer? Note that you only need to start measuring when room temperature. You need to draw liquid from each “can”, of which there are six in the car’s battery (including on trucks). Then the float will automatically rise and show the current density of the measured liquid.

How to read testimony? For this, a special scale is provided with values ​​that correspond to immersion to a specific division. Part of the float will be above the surface. The value of the division on the offshoot will determine the current density of the electrolyte.

Kinds

Today there are several types of data measuring devices:

• Mechanical hydrometer.
• Electronic.

The first type is a round flask with a float inside. In digital, the scheme is somewhat different. An electronic hydrometer is a kind of probe with a metal end. At the top there is a digital display. Such a device works on ordinary batteries, thanks to sensors. However, there is little demand for such devices on the market due to their high cost. A mechanical analogue costs 10-15 times cheaper, and therefore is used most often.

Why is it so important to monitor density?

What is a hydrometer, we have already found out. At first glance it may seem that this device is not needed. But it is he who allows you to notice in time low level density and prevent serious consequences. If we talk about antifreeze, it can freeze at near-minus temperatures. As you know, coolant, in which there is a lot of water, expands when it freezes. As a result, the pipes burst and the radiator is deformed. Naturally, you can not continue to move on such a machine.

If we talk about the battery, with a low density of the electrolyte, such a battery is not able to quickly restore the charge. As a result, the battery voltage is always below normal - 11.0-11.5 volts. When starting the engine, the starter takes another 2 volts, which leads to a deep discharge of the battery. All this significantly reduces battery life. That's why it's important to know how to use a hydrometer. Below we will look at how to take measurements.

Making measurements on the battery

Consider how to use a hydrometer for a battery. To do this, it is necessary to provide access to the banks of the battery. The covers can be unscrewed with a thick slotted screwdriver. Next, we immerse the glass flask-tube inside and take part of the liquid with a pear. The float must float freely and be vertical. How to know the result? The density level is considered to be the place where the scale is in contact with the electrolyte. Having measured the data on one bank, we move on to the next. Please note that after measurements, the pumped out electrolyte is returned to the jar from which it was taken.

Safety

Before checking the density of the electrolyte with a hydrometer, you should put on rubber gloves. It is also important to protect the sleeves as this fluid is very corrosive. If the electrolyte comes into contact with the skin, immediately rinse the damaged area under running water.

This liquid aggressively affects not only the skin, but also clothing. It is better to use things made of dense fabric, since the electrolyte can partially corrode them. Be careful not to get liquid in your eyes. Goggles will not be superfluous.

How to level up?

The ideal result is a density of 1.27 grams per cubic centimeter. If this parameter is 1.23 or lower, the density must be urgently increased. How to do it? To do this, you should purchase an electrolyte (it is available in any automotive store). If the density is extremely low (less than 1.18 grams per cubic centimeter), it is better to completely pour out the electrolyte present in the battery, further washing the insides with distilled water. Work should be done with rubber gloves, otherwise serious burns are possible.

After that, we pour a new electrolyte into each of the cans until it completely covers the surface of the plates. It is desirable that its level be 1.0–1.5 cm higher than the lead plates. Next, put the battery on charge. The charger must be set to low current. Without twisting the lids, we wait until some of the liquid has boiled away. After a couple of hours, remove the battery from the charger. After waiting another hour, we freeze. The density should be between 1.27 and 1.29 grams per cubic centimeter.

Hydrometer for antifreeze

Also in stores there are similar meters for coolant. They operate on the same principle, based on the law of Archimedes. How to use such a hydrometer? The instruction is practically no different from measuring the density of the electrolyte.

So, we need to unscrew the lid expansion tank and take some liquid from there. It should fill at least half the volume of the flask. Next, we will notice how the float begins to rise up. The place where it comes into contact with the liquid will be our result. The ideal value is 1.07 or 1.10 grams per cubic centimeter. In this case, the freezing point of the liquid will be -40 degrees Celsius. If the value approaches one, crystallization will occur earlier - up to zero degrees.

Also note that some models have a scale that changes its shade depending on the suitability of the antifreeze for use. So, the green scale indicates that the liquid is suitable for winter period. Partial or complete loss of frost resistance is determined by the yellow or red scale.

How to return the density of antifreeze?

Here the technology is somewhat different. In order for the antifreeze not to freeze at near-minus temperatures, a concentrate should be added to it. It usually has a crystallization temperature of -80 degrees and is sold in liter bottles. Often one eggplant is enough to shift the freezing threshold by 10-15 degrees. Having added the required amount of liquid, you can safely proceed to operation.

About cost

If we talk about mechanical products, their cost varies from 140 to 320 rubles. The cost of digital ones starts from 5 thousand rubles.

Note that the devices are strictly divided by scope. On sale there are hydrometers for electrolyte and for antifreeze.

Conclusion

So, we found out what a hydrometer is and how to use it. As you can see, it's quite useful thing useful for every car owner. It is worth having two hydrometers available - for antifreeze and for electrolyte. Density measurements in the battery are recommended to be done at least once a year. And as for the coolant, you need to check it only after mixing it with distilled water (when the antifreeze level was previously low). It is worth remembering that the greater the percentage of water in the coolant, the lower its crystallization threshold.

Measuring the density of the electrolyte in a battery is an essential part of battery maintenance. In order to periodically perform this check, special methods and devices are used. However, there are many things to consider in this case.

In order to verify the density of the electrolyte in the battery, it is necessary to use a device called a hydrometer. In some cases, it is called a densimeter, but this concept is not accurate enough.

Most hydrometers consist of the following parts:

It should be remembered that when checking the density of the electrolyte, the hydrometer must be at rest, without touching glass walls, so it must be held vertically in front of the face.

Instructions: how to check the density correctly

1. The first step is to start by assembling the device itself. The float is placed in a glass flask, on one side of which a pear is put on, and on the other, a tip and a stopper.
2. Next, draw the liquid into the flask. Squeeze the pear, gradually loosening the grip. The result should be a calmly floating in the liquid in vertical position float.
3. Read the value on the scale, at the point where the device comes into contact with the liquid.
4. The final destination will be the mandatory flushing of the device. This will not allow the readings to be mistaken during further operation of the device.

Care should not be taken when handling the electrolyte, as sulfuric acid is hazardous to health!

Principle of operation: determination of the ratio of the mass of liquid to the volume of the float-pycnometer

The density of the electrolyte, which is a sulfuric acid solution, in the battery is measured in g / cm3. It depends on the concentration of the solution itself, as well as on the degree of charge of the battery, since when the battery is discharged, a certain amount of sulfuric acid moves into the plates and the density will decrease.

For this reason, the battery density must be measured at a temperature of about 25 °C and with a fully charged battery. In a new charged battery, it should be 1.28±0.01 g/cm3. Depending on the climate and season, readings may vary. Standard values ​​for the density of acids and alkalis used as an electrolyte are from 1.22 to 1.29 g/cm3 at a temperature of 20 to 30 °C.

As the battery discharges, the density will decrease in readings. When the battery is discharged to half the exponential density, it will be about 1.20 ± 0.01 g / cm3. When fully discharged, the density will be no more than 1.10±0.01 g/cm3.

Density drops by 0.01 g/cm3 from normal when the battery is 5 percent discharged. Frequent recharging can harm the operation of the device, so you can normalize the density of the liquid with distilled water.

One of the varieties of hydrometer for motorists is a device with a set of floats of different masses and with an identical volume in glass vessel. Each of them is equipped with one label. The principle of this mechanism is that the float with the closest value will rise when the others sink.

Important! With a stable overestimated density of the electrolyte, the life of the battery is shortened.

Features and measurement accuracy

When reading indicators from a hydrometer, one should take into account small feature. A more accurate indicator is shown not at the point of contact between the water and the float, but from the meniscus. This is the name of the lower part of the curvature of the surface of the liquid. Indicators should be written off from this lower part, so the information will be more reliable.

Device disadvantages:

• Somewhat large amount of fluid being measured
• The scale is non-linear
• A small range of values ​​that are measured is limited to the initial section of the scale.
• The outer surface of the cylindrical float is subject to contamination
• The capillary characteristics of liquids are different, which adversely affects the result of the test.

If the indications for the desired temperature by measuring the density of the electrolyte are not met, it is necessary to make calculations referring to the following data:

Detectable problems

One of the advantages of a hydrometer is the safety of measuring the density of liquids with an accuracy of 0.05-0.1%. Moreover, this method requires a large number substances to measure.

The battery in the car regularly performs its work with such an indication of the electrolyte: at a temperature of 25 degrees 1.28 g / cm3. A similar result in the values ​​\u200b\u200bis available for new batteries, with proper certification.

In the event that the readings on the density of the electrolyte in one of the cans of the battery are lower, this indicates a short circuit: the closing of the lead plates and, as a result, a breakdown battery.

If the density is below normal in the entire battery, this may indicate problems such as:

If the electrolyte density readings are incorrect, the problems should be corrected. It is worth remembering that if the density is low in only one of the cans, the battery cannot be repaired and should be replaced.

The exact cause of the problem will help to establish additional voltage measurements with and without load.

Attention! During operation, the batteries lose some of the water, thereby reducing the level of liquid above the plates, increasing the concentration of acid. For this reason, the electrolyte level must be checked before testing. The level accepted as the norm is 10-15 mm above the upper line of the separators.

Why is verification so important?

Checking the electrolyte density regularly will help you anticipate and troubleshoot problems with your device. Over time, the operation of the battery, one way or another, it will work worse than on the first day after purchase. Therefore, you should take care of him and follow him, then he can live up to 10 years.

Important! Topping up electrolyte from other batteries should be avoided, as this will reduce the life of the device.

The density of the electrolyte in winter should be 1.27 g/cm3. A lower indicator affects the operation of the device, the car will be more difficult to start, sometimes leading to freezing of the electrolyte.

Using a battery with a low charge at low temperatures can lead to the destruction of the lead plates. The density test also allows you to determine the discharge: the lower the density, the more discharged the battery.

Useful video

A simple operation for measuring density with a hydrometer is fully presented in this video.

Conclusion

In general, the density determines the capacity of the battery and its service life. Each device needs constant monitoring and care. One option to give your battery proper attention is to regularly check its density with a hydrometer. With this attitude, there will be no surprises in breakdowns and it will be possible to predict future problems.

All professional motorists know that any car requires care and maintenance. Important in this matter is the maintenance of a very important device in working order - the battery, which ensures the start of your car and smooth operation all electrical systems.

In order for the battery to serve for a long time, it must be serviced. As we know, our car battery is filled with electrolyte and it performs important role in work this device. We wrote about the electrolyte in detail in the article, and now let's talk about how to measure important parameter this solution of acid and water is the density.

What is a hydrometer

First, a few words about density, density is specific gravity acid, which is mixed with distilled water, in relation to the entire volume of the solution. Simply put, this is the acidity of this mixture.

Density is measured with a hydrometer, the principle of which is based on the law of Archimedes, according to which a buoyant force acts on a body immersed in a liquid, the value of which is equal to the weight of the liquid displaced by this body.

The density of the liquid under study, in our case, the electrolyte, can be determined by the depth of immersion of the hydrometer, i.e. the volume of liquid displaced by it, and the weight of the hydrometer.

Hydrometer design for electrolyte

Hydrometers are different, it all depends on the density of which liquid you will measure. Since this information site is about batteries, we are of course interested in a device that is popularly called a “car hydrometer”. The design of a car hydrometer is quite simple. It consists of:

1. glass or plastic tube
2. rubber pear
3. Pipettes
4. Hydrometer

A rubber pipette with a long nose is attached to one end of the glass tube to reach the battery plates. Why rubber, so as not to damage the plates and battery separators.

A hydrometer is inserted into the inside of the tube, which is a hermetically sealed glass tube, inside of which a ballast weight is laid at one end (metal, or maybe some other substance, can serve as a weight). From the other end, this tube flows into a glass rod of a smaller diameter on which a measuring scale is applied.

On the other side of the glass tube-case, a rubber pear is attached, with the help of which we pump the electrolyte from the battery into our hydrometer and back into the battery jar.

There are, of course, devices for measuring density and a slightly different design. For example, the float “Density Indicator”, inside the cavity of which there are several plastic floats of various colors.

It works on the same principle as the hydrometer described above, on the same laws of physics. In the same way, the electrolyte is pumped into the device using a rubber bulb and pop-up floats show the density of the solution. However, the accuracy of measurements with such a “Density Indicator” leaves much to be desired, the floats either float or do not float, although the electrolyte is the same.

Safety precautions when measuring electrolyte density with a hydrometer

Before you start measuring the density of your battery electrolyte with a hydrometer, you should remember that you are working with acid and basic safety measures must be observed.

Be sure to wear goggles to protect your eyes, rubber gloves and an apron. Electrolyte contact with open areas skin and eyes will cause chemical burns.

If the electrolyte comes into contact with the skin or eyes, immediately rinse these places with plenty of running water for 15 - 20 minutes, after that you can wash the burned areas with soapy water or a solution of water with soda at a concentration of a teaspoon per 200-300 ml of water, with these actions you will lower the concentration chemical. Treatment of affected areas of the skin does not cancel the call for an ambulance or an urgent visit to the hospital.

How to measure density with a hydrometer

To measure the density of the electrolyte in the battery, it is necessary to withstand the conditions on which the readings of our measurements depend:

1. The battery must be charged
2. It is impossible to measure the density immediately after charging, you need to wait 3-5 hours.
3. The hydrometer readings should be corrected depending on the temperature of the electrolyte.

The most accurate data will be at a solution temperature of 27 degrees C. If the temperature is lower, you need to subtract 0.004 fractions of a unit for every 6 degrees C, if higher, add the same value.

Before unscrewing the caps of the battery cans, carefully wipe the surface of the battery so that dirt does not get inside, this can serve to reduce the life of your product.

The measurement procedure itself is quite simple. We assemble the hydrometer: we attach a pipette to the body-tube, place a densimeter in the body, and close the body on the other side with a rubber pear.

We measure the density in each jar in turn. To do this, we lower the pipette nose to the plates and draw an acid solution into the hydrometer body using a rubber bulb. You should not collect a lot of electrolyte, the densimeter may rest against a pear and the readings will be inaccurate, if there is not enough solution, then the densimeter will not float. It is necessary to collect such an amount of acid solution that the densimeter floats without interference.

The density readings of our electrolyte can be viewed at the intersection of the hydrometer scale and the surface of the solution. Keep in mind that devices have different scales, some write readings in g / cm3, but there are scales in kg / m3, then in order to get the numbers we are used to, the readings must be divided by 1000.

Depending on the values ​​that you have received, you can decide to adjust the acid solution. How to raise the density of the electrolyte, we wrote earlier in the article.

Some hydrometers have a scale for measuring the density of antifreeze with a hydrometer. Why is it necessary to measure the density of antifreeze? This indicator is mainly needed in winter and in northern regions countries. The fact is that by the density of antifreeze we can determine the temperature of its crystallization (freezing), this is very important when low temperatures to ensure the normal functioning of the car engine.

Be sure to rinse the hydrometer after use at least three times and preferably with distilled water. This simple procedure will extend the life of your device for more than one year.

Sold brands of hydrometers in Russia

The choice of brands of hydrometers in the market of our country is quite large, but in fact they represent almost the same devices. The differences are only in the quality of the material used for the manufacture of devices.

Hydrometer IP1

The IP1 hydrometer stands out from the general monotony, which is not made with a standard glass hydrometer, but with a set of plastic sticks, opposite which the density value is written on the case. After filling the cavity of the device with electrolyte, the sticks float and the density value is read on a scale from the one that surfaced last.

The measurement limit of this device is from 1.19 g/cm3 to 1.31 g/cm.

Scale division value 0.02 g/cm.

Hydrometer IP1 - “Density Indicator - 1” is not an entirely accurate device, but it is quite common among motorists, probably due to its low cost ( approximate cost in stores 100 rubles) and compactness.

Hydrometer Orion AR-02

Against the background of all this diversity, products that are already familiar to us from the series stand out. chargers, enterprises from St. Petersburg LLC "NPP ORION SPB" hydrometer Orion AR-02.

This is the only device for which I found instructions. She can.

The principle of operation, safety precautions and the measurement process are described above, let's see how the rest of the specimens look in the pictures and some short videos.

Hydrometer for electrolyte Autovirazh AV-9901

Hydrometer for electrolyte Sparta 549125

A car battery is a vital organ in its overall electromechanical system. Without his work, start the engine, in the usual way, impossible.

So that your battery, as usual, at the most inopportune moment does not play a cruel joke with you, you need to periodically check its density. This article will focus on serviced batteries.

Checking the density of the battery with a hydrometer

To understand this issue, it is first necessary to understand what a device for checking the density of battery electrolyte is - a hydrometer.

Hydrometer is the simplest device serves to measure the density of a liquid, and the principle of its operation is based on the well-known law of Archimedes.
He looks like this.

Ordinary glass tube top part which is narrowed and has a scale with divisions. The lower part of the tube is wide; it contains shot or mercury, which is filled with a strictly defined amount during the calibration of the hydrometer.

The device, as a rule, is sold in car dealerships in a set with a rubber “pear” for taking electrolyte and a volumetric flask in which the hydrometer itself is located.


Let us consider in detail how to check the density of a car battery?

• First of all, put the battery in a clean place and flat surface, do not forget that the electrolyte is an acid and any drop spilled on clothes will ruin it forever. And if it comes into contact with the skin, it will cause chemical burn.
• Clean the battery of dirt. Any dirt that gets into a jar of electrolyte can change the density in this container, which will inevitably lead to damage to the entire battery.
  After removing the lids from the jars, check the electrolyte level and top up if necessary. Most often, distilled water is added, but sometimes in the case that we will discuss below, it is necessary to add electrolyte.
• Another prerequisite before checking the density is to fully charge the battery.

Important! In the process of charging the battery, hydrogen and oxygen gases will be released from the cans. A large concentration of these gases can lead to an explosion, so the room must be well ventilated.

The charging process is not fast, so you have to wait a while for 5-6 hours. It all depends on the degree of discharge of your battery and the capabilities of the charger.

A motorist’s kit will not include an AET-1 hydrometer for electrolyte and antifreeze, which is designed to measure the density of the electrolyte in acid and alkaline batteries (Fig. 1) in the range from 1100 kg / m 3 to 1300 kg / m 3 and determine the freezing point of antifreeze (Fig. 2) in the cooling system of a car engine in the range from minus 5°С to minus 40°С, as well as from a device for extracting liquid (electrolyte or antifreeze). The hydrometer is inside plastic tank, and when taking the measured liquid with the help of a rubber bulb, it occupies a certain position, which is read by a person by the level of the meniscus. All parts of the hydrometer are packed in plastic tube which is covered with a lid. The cover is made in the form of a small funnel, through which it is convenient to pour the electrolyte into the battery.

1. COMPLETENESS AND TECHNICAL CHARACTERISTICS

1.1. Hydrometer for electrolyte and antifreeze AET-1, pcs... 1
a) electrolyte density measurement range, kg/m 3 ... from 1100 to 1300

• scale division value for electrolyte, kg/m3 ... 10
• permissible error limit, kg/m3 ... ±10

b) range of readings of antifreeze freezing point, °C... from minus 5°C to minus 40°C

• price of division of the scale for antifreeze, ° С ... 5
• permissible error limit, °С... ±5

1.2. Liquid sampling device (electrolyte or antifreeze)

• polymer pipette, pcs... 1
• rubber balloon, piece... 1
• rubber plug, piece... 1
• stopper with a rubber tip, piece... 1

1.3. Passport, piece... 1
1.4. Packing tube, piece... 1
1.5. The weight of the hydrometer with a case and a passport is 135 gr.
1.6. Hydrometer length in assembled, prepared for work - 350 mm.
1.7. The length of the packaging tube assembly is 305 mm.

2. DESIGN AND OPERATION

2.1. The hydrometer is a float, in the upper part of which a paper scale is placed, graduated in units of density kg / m 3 for electrolyte and in degrees Celsius (°C) for antifreeze.
2.2. The liquid sampling device is used to select electrolyte from the battery or antifreeze from the engine cooling system.
2.3. Before starting work, it is necessary to assemble the liquid sampling device, as shown in Fig. 3
With the help of a balloon, electrolyte or antifreeze is sucked into the pipette through the tip of the cork in such an amount that the hydrometer floats freely in a vertical position.
2.4. The line of contact of the liquid with the hydrometer rod corresponds to the density of the electrolyte in kg / m 3 or the freezing point of antifreeze in ° C (Fig. 4).
Measurements should be carried out at a temperature of (20 ± 2)°C.
If measurements are carried out at a temperature other than 20°C, then the following corrections must be added or subtracted to the measurement results (table 1) .
For example: If at a given measurement temperature the correction according to the table has a minus sign, then it is subtracted from the measurement result. If the correction is with a plus sign, then it is added to the measurement result.

Table 1.

2.5. After taking measurements, the hydrometer and the liquid sampling device must be washed clean water and wipe dry.

Good to know:

Table 2.

3. WARRANTY

Warranty period of operation is 24 months from the date of sale through a retail network.

Produced by: Russia, OOO Citadel, Belgorod, st. Working, 12