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How to use a hydrometer to measure the density of an electrolyte? Nuances in the household use of alcohol meters

Measuring the density of the liquid in the battery is one of the important stages of battery testing and diagnostics. It is enough to take measurements with a hydrometer to obtain reliable data on the state of the electrolyte. The density of a liquid is important for many reasons. One of them is the possible contact of lead plastics with each other and their subsequent resolution. The density of the electrolyte decreases for many reasons. The first is a natural change in condition over the years of operation. battery. The second is the constant addition of distilled water to the battery jars, which dilutes the electrolyte, but maintains its level. You should not add sulfuric acid or ready-made electrolyte from other batteries to the jars - this will only speed up the failure of the battery.

If you notice serious problems with a car battery, use diagnostic methods known since ancient times. For diagnostics, you will need a hydrometer that measures the density of the electrolyte and tells you about the condition of the battery. Below in the post we will look at how to use a hydrometer and how to correctly read the data it provides. We will also consider the features of the information from this device and possible ways troubleshooting problems that have arisen.

How to use a hydrometer to measure the density of liquid in a battery?

It is not possible to lower the hydrometer device directly into the battery jars, so you will have to pump out some electrolyte and check its density. Remember that each battery bank operates independently of each other, so you will have to measure the density of the liquid for all working spaces present. Pump out required quantity liquid into a special flask for subsequent measurement using any tube, one end of which can be closed with a finger. The sequence of actions in this case will be as follows:

  • make sure that the tube does not melt under the influence of an aggressive environment - acid from the battery;
  • insert part of the tube into the jar so that the liquid gets inside and remains at the same level throughout the jar;
  • close the top hole of the tube with your finger, lift the collected liquid and pour it into the flask;
  • repeat this process required amount times to get the right amount of liquid;
  • Next, you need to lower the hydrometer into the flask, wait for it to level and look at the number that is on the line of the surface of the liquid;
  • this figure will indicate the density of the electrolyte in your battery that you are looking for;
  • Next, you should do this procedure with all battery banks to get a reliable picture of the battery condition.

Be careful when performing this procedure, because you will have to work with aggressive acid, which should not come into contact with the skin, eyes or mouth of a person. If even a small particle gets on you, unpleasant consequences are guaranteed. We recommend protecting yourself with high-quality acid-resistant gloves, as well as a good flask that will not melt from exposure to aggressive substances. Using a hydrometer you will only get certain data about the condition of your battery, but interpreting and using it correctly is not an easy task which requires specialized knowledge.

Electrolyte level and density are two important factors for good battery performance.

A car battery works without interruptions and problems if the density of the electrolyte at +25 degrees Celsius is 1.28 g/cm3. This value applies to all new batteries that have not been used in vehicles and are factory certified. If the density in one of the cans is lower, we can assume that something has happened in this part of the battery. short circuit, the lead plates touched each other, causing the battery to break down. If the density of the liquid is below normal throughout the battery, this indicates such possible problems:

  • the battery is deeply discharged, it can no longer perform its functions in full mode;
  • the battery went through the sulfitation stage and received certain problems in the chemical reaction;
  • the battery has gone through excessive wear when the generator fails and the engine runs on battery power only;
  • The battery is simply outdated and needs to be replaced due to too much age and wear;
  • the car battery was produced by a manufacturer who does not check the quality of the product;
  • This is not a factory battery, but a fake that does not provide much reliability.

Any problems can be solved, and the most popular solution to the problem of too low electrolyte density is to charge the battery. If you can increase the density by charging, then the battery will still be able to serve for some time. After charging, the electrolyte level in the jars decreases slightly, so you may need to top up with distilled water after completing several charging stages. Low electrolyte levels cause contact with lead cells and significantly increase the risk of failure of the entire battery. Therefore, monitor the liquid level in the jars if your battery allows for maintenance.

When should you change the battery and not repair it or try to charge it?

Today, a popular trend among battery manufacturers is the production of batteries that cannot be serviced. We are even talking about the difficulty of charging the battery, not to mention the problems with measuring density internal environment. Such batteries do not have holes to examine the inside of the battery. Often this does not allow you to get the necessary conditions to detect battery problems that necessitate replacing the battery with a new one. Of course, for the manufacturer this is the most profitable option. Replacing a car battery is mandatory in the following cases:

  • the gel battery is discharged - these types of batteries cannot be maintained or charged in any way;
  • a complete deep discharge occurred due to a generator failure, the battery stopped taking a charge when the device was connected;
  • the liquid in the battery jars looks cloudy - lead plates have fallen off and cannot be restored;
  • the electrolyte level began to actively and constantly fall, which causes the battery to fail in normal operation;
  • servicing the battery is impossible due to the lack of plugs for unscrewing upper parts cans;
  • The battery became depressurized and the electrolyte began to flow out of it directly into the engine compartment.

Do not allow electrolyte to leak inside the engine compartment, as this may cause a fire in the wiring or car tires. Be careful with any manifestations of interaction with acid, since many batteries are filled with an incredibly explosive mixture of acids, which certainly will not make your skin soft and silky. When using a hydrometer and other means of checking a car battery, it is worth remembering possible problems and malfunctions that cannot be corrected. Therefore, in any case, you should prepare to buy a new battery as soon as the old one begins to show its character. Watch a video with recommendations for measuring the density of electrolyte in a battery:

Let's sum it up

High-quality batteries can provide up to 8-9 years of service without problems or interruptions. However, you need to pay attention to the operating characteristics of the battery, charge it if necessary and carry out maintenance of the electrolyte and the internal space of the battery. Once you start keeping an eye on all of these features, you can protect your battery from unexpected problems with fluid changes and other issues.

By purchasing a high-quality battery for a car, you will get excellent operation of the equipment and will be able to use the battery very well without any unnecessary difficulties. for a long time. But if you notice a fatal malfunction in your car’s battery, you should urgently go to a specialized store and purchase new battery. This is the only way to protect yourself from untimely failure of the power source. Have you ever measured the density of the electrolyte in your car battery?

IN Everyday life sometimes you need to check the density of some substance, for example, alcohol, acid, milk. For this, a hydrometer is used; it is also used to check the density of the electrolyte. If the owner motor vehicle expects that the battery will work as long as possible, he should check what the density of the electrolyte is. Why do you need a hydrometer - a device that allows you to measure the level of acidity of the solution in the battery cells.

What is a hydrometer

A hydrometer is a glass float that expands downwards and is filled with a weighty mass - ballast, working according to Archimedes' law.

Some types of hydrometers are used to measure the acidity and temperature of antifreeze. The device includes:

Types of hydrometers

There are several types of hydrometer; for practical use, a scale is applied to the hydrometer in accordance with the diluted substance, for example:

How to use a hydrometer correctly

The performance of a car battery depends on the density and concentration of the electrolyte, and it is important to check and adjust this parameter in a timely manner.

A car battery is a source of current with galvanic reactions. The electrolyte is a solution of acids and alkalis of a certain density. Standard values ​​range from 1.22 to 1.29 grams/cm3 at temperatures from 20 to 30 °C.

A decrease in density by 0.01 grams/cm3 indicates a battery discharge of 5-6%. When charging it rises to normal. With numerous recharges, the density of the liquid changes and its adjustment is necessary. It is produced by adding distilled water or acid with intermediate measurements.

Density is the mass of sulfuric acid mixed with water relative to the whole volume of the solution, that is, the level of acidity of the mixture. According to the law of hydrostatics, when a body is immersed in a liquid, its weight is equal to the mass of the displaced volume of liquid. A hydrometer operates on this principle; it accurately determines the acidity of the mixture in grams/cm3.

Measuring the density of the liquid in a battery is not difficult, but it requires neatness and attention.

Step-by-Step Guide to Measuring Battery Electrolyte Density

  • Measure electrolyte density The battery can be charged if about 6 hours have passed since it was charged. It is necessary to unscrew all battery cell plugs.
  • Take the device and lower it vertically into the battery cell. The device looks like a glass flask, which has a float - a hydrometer with a scale, and at the end of the device a rubber bulb for collecting electrolyte. We collect a certain amount of acid so that the hydrometer floats without difficulty. We look at the scale and take readings. The electrolyte has high density the float floats higher. The unit for measuring density is kilogram per cubic decimeter, liter.
  • Let's look at the readings. The density should be about 1.24 kilograms per liter. The difference in measurements in other battery cells is 0.03 kilograms per liter. At low densities, the battery needs to be recharged.
  • With normal readings screw in the plugs. It is necessary to use original plugs with gaskets.
  • If the instrument readings not normal, change the battery.

Safety precautions

When working with electrolyte, you must adhere to safety criteria. You should wear protective gloves, glasses, clothing and shoes. Avoid contact of electrolyte with exposed body parts and eyes. All actions must be carried out in a warm, ventilated room, as toxic gas is released.

If acid gets into your eyes or skin, rinse with plenty of water. If the burn is severe, then you need to drink as much warm water as possible and take analgin. After this you need to quickly head to medical institution. If acid gets on clothing, it must be thrown away. When working with antifreeze, you must also follow safety precautions. The radiator cap is opened only after the liquid has completely cooled to prevent its release and causing burns.

After use, the hydrometer is washed in running water. If this condition is met, the device will work for decades.

Popular hydrometer models

Manufacturers offer different kinds devices, varying in cost, appearance and functions.

  • Sparta 549125. A model of compact dimensions with a strong glass body and a low price.
  • SKYBEAR 623000. Inexpensive Chinese equivalent, not a bad thing for little money.
  • Orion AR-02. For electrolyte domestic production(NPP Orion, St. Petersburg). The container is made of glass, the float sometimes sticks to it, which makes you nervous when taking measurements.
  • . For professional use. They measure the characteristics of all kinds of liquids, including the acidity of the electrolyte and the temperature of the antifreeze. An expensive model, but very convenient to set up with distilled water.

Using a hydrometer, you can obtain certain data about the condition of the battery. It is necessary to monitor the density of the electrolyte. Electrolyte level and density are important parameters for good battery performance.

Measuring the density of the electrolyte in the battery is an integral part of caring for the structure. In order to periodically perform this check, use special methods and devices. However, in this case there is a lot to consider.

In order to verify the density of the electrolyte in the battery, you need to use a device called a hydrometer. In some cases it is called a densimeter, but this concept is not precise 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 you need to hold it vertically in front of your face.

Instructions: how to check density correctly

  1. The first step is to start by assembling the device itself. The float is placed in a glass flask, with a bulb on one side and a tip and stopper on the other.
  2. Next, you should collect the liquid into the flask. Squeeze the pear, gradually loosening your grip. The result should be a vertical position float.
  3. Read scale value, in the place where the device comes into contact with the liquid.
  4. The final point will be the mandatory flushing of the device. This will prevent erroneous readings during further operation of the device.

You cannot ignore precautions when handling electrolyte, as sulfuric acid is hazardous to health!

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

The density of the electrolyte, which is a sulfuric acid solution, in a battery is measured in g/cm3. It depends on the concentration of the solution itself, as well as on the state 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, battery density must be measured at a temperature of about 25 ° C and with the battery fully charged. In a new charged battery it should be 1.28±0.01 g/cm3. Depending on the climate and season, readings may vary. The standard densities of acids and alkalis used as electrolytes range from 1.22 to 1.29 g/cm3 at temperatures from 20 to 30 °C.

As the battery discharges, the density will decrease in readings. When the battery is discharged to half, the indicative density 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 reduces performance 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 using distilled water.

One of the types of hydrometer for motorists is a device with a set of floats different weights and with identical volume in a glass vessel. Each of them is equipped with one tag. The principle of this mechanism is that the float with the closest value will float when the others drown.

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

Features and accuracy of measurements

When reading readings from a hydrometer, you 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. So called Bottom part curvature of the liquid surface. Indicators should be written off precisely from this lower part, so the information will be more reliable.

Disadvantages of the device:

  • Somewhat large amount of liquid that is being measured
  • The scale is nonlinear
  • A small range of values ​​that are measured is limited by the initial portion 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 test result.

If the readings for the desired temperature by measuring the electrolyte density 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 does not require large quantity substances to measure.

The battery in a car performs its job properly with the following electrolyte reading: at a temperature of 25 degrees 1.28 g/cm3. New batteries with proper certification have similar results in values.

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

If the density is below normal throughout the 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 corrected and should be replaced.

Additional voltage measurements with and without load will help determine the exact cause of the problem.

Attention! During operation, batteries lose some of the water, thereby reducing the liquid level above the plates and increasing the acid concentration. For this reason, it is necessary to check the electrolyte level before testing. The level accepted as the norm is 10-15 mm above the top line of the separators.


Why is verification so important?

Regularly checking the electrolyte density will help to anticipate and resolve problems with the device. Over time, the battery will work worse than on the first day after purchase. Therefore, you should look after him and monitor him, then he can live up to 10 years.

Important! Avoid adding electrolyte from other batteries, as this will reduce the service life of the device.

The electrolyte density 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 low-charge battery at low temperatures may cause the lead plates to deteriorate. The density can also be determined by checking the density: the lower the density, the more discharged the battery.

Useful video

The simple operation of measuring density with a hydrometer is fully presented in this video.

Conclusion

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

1. Purpose and general information

1.1. A hydrometer for electrolyte, antifreeze, antifreeze and washer fluid with a built-in thermometer complete with a device for collecting liquid (a set for a motorist) is designed for selecting and measuring the density of the electrolyte in the battery ( Fig.1), determining the freezing temperature of the coolant in the engine cooling system (Fig.2) and the freezing temperature of the washer fluid in the car windshield and headlight washing system ( Fig.3), as well as for measuring the temperature of the test liquids (electrolyte, antifreeze, antifreeze, washer fluid).

1.2. As an electrolyte in car batteries Aqueous solutions of sulfuric acid are used.
1.3. Coolants and washer fluids belong to the antifreeze group. Antifreezes are frost-resistant liquids that freeze at temperatures below zero degrees Celsius (°C) and differ in the basis of their preparation and scope of application.
1.4. Coolants are antifreezes made from ethylene glycol and propylene glycol. Antifreeze is a brand of antifreeze based on ethylene glycol.
1.5. Washer fluids (washers) are antifreezes made on the basis monohydric alcohols: methyl, ethyl and others.
Washers based on methyl alcohol - methanol, as washer fluids, are prohibited for use in many countries (they have a negative effect on vision, motor and nervous systems).
Mix antifreezes made in on different basis, Not recommended.

2. Delivery set

2.1. Hydrometer with built-in thermometer AETOTr: 1 pc.;
2.2. The device for collecting fluid (electrolyte, coolant and washer fluid) consists of:
- pipette: 1 piece;
- pear: 1 piece;
- plug with tip: 1 piece;
2.3. Passport: 1 pc.;
2.4. Packaging case: 1 pc. (the lid of the pencil case is made and used as a watering can (funnel)).

3.Design and technical characteristics

3.1. A hydrometer for electrolyte, antifreeze and washer fluid with a built-in thermometer AETOTr TU U 33.2-24667973-004:2007 is a glass float, in the upper part of which a paper hydrometer scale is placed, and in the lower part there is a thermometer built-in. The hydrometer scale consists of three main scales - scale electrolyte, antifreeze, washer (Fig.4).

3.2. Scale electrolyte graduated in density units g/cm3
- electrolyte density measurement range: from 1.10 to 1.30 g/cm3
- scale division price: 0.01 g/cm3
- permissible error limit: 0.01 g/cm3.
3.2.1. The colored bars on the electrolyte scale indicate the percentage (%) of battery charge:
- yellow bar - battery is low,
- red - charged 50%,
- blue - 75%,
- green - 100% charging.
3.3. Scale antifreeze consists of two scales (one located on the left, the other on the right), graduated in degrees Celsius with a minus sign (-° C) and designed to determine the freezing temperature of coolants.
3.3.1. The scale on the left is designed to determine the freezing point of the coolant based on ethylene glycol:
- range for determining the freezing temperature of the coolant: from 0 to minus 40 ° C;
- scale division price: 5° C.
3.3.2. The scale on the right is designed to determine the freezing point of the coolant based on propylene glycol:
- range for determining the freezing temperature of the coolant: from 0 to minus 30 ° C;
- scale division price: 5° C.
3.4. Scale washer consists of two scales (one located on the left, the other on the right), graduated in degrees Celsius with a minus sign (-°C) and designed to determine the freezing temperature of washer fluids.
3.4.1. The scale on the left is designed to determine the freezing temperature of washer fluid made from ethyl alcohol- ethanol:
- detection range for washer fluid freezing: from 0 to minus 40°C;
- scale division value: 5°C.
Washers made on the basis of ethyl alcohol - ethanol can be recognized by the flame icon on the packaging.
3.4.2. The CIS market is supplied with washer fluids whose density differs from the density of liquids made on the basis of ethyl alcohol - ethanol. Having studied the densities and freezing temperatures of these liquids, we constructed an average scale for them, highlighting in color the ranges of possible freezing of these liquids:
- yellow- the washer fluid freezes to minus 20°C;
- red - freezes at minus 20°C;
- green - below minus 20°C.
3.5. The scale of the built-in thermometer is calibrated in degrees Celsius (°C) and is designed to determine the temperature of the liquid being tested, which allows for corrections to the hydrometer readings (Table 1) to be taken into account if the liquid temperature differs from 20±2°C:
- temperature measurement range of the test liquid: from minus 40 to plus 40°C;
- scale division value: 5°C.

Table 1

4. Operation of the device

4.1. Before starting work, it is necessary to assemble the liquid sampling device, as shown in Fig.5.

4.2. Squeeze the bulb and lower the tip of the plug into the liquid being measured. Slowly unclenching the bulb, allow the liquid to fill the pipette in such an amount that the hydrometer floats freely in a vertical position. When reading readings from the hydrometer scale, the level and line of contact of the liquid with the hydrometer rod should be below the pipette corrugation (Fig. 6), and the hydrometer rod inside the corrugation. Point contact of the hydrometer rod to the inner corrugation of the pipette prevents continuous sticking of the hydrometer to the pipette wall.

4.3. The line of contact of the liquid with the hydrometer rod corresponds to:
- on a scale electrolyte- electrolyte density;
- on a scale antifreeze- freezing temperature of the coolant;
- on a scale washer- freezing temperature of the washer fluid.
Readings are taken according to bottom edge meniscus Measurements should be made at a temperature of 20±2°C.
4.4. If measurements are made at a liquid temperature different from 20±2°C, then the correction given in Table 1 should be added algebraically (that is, with its sign) to the measurement results.
The amendments in Table 1 for coolant and washer fluids are given for their optimal concentrations corresponding to the freezing point of these fluids at minus 40 °C. Coolant corrections highlighted in red are for reference only because when low temperatures liquid, the correction is so large that the freezing temperature value on the hydrometer scale will go beyond the measurement limits of the device. For coolants, we recommend taking measurements at temperatures of plus 10°C and above.
4.5. After taking measurements, the hydrometer and liquid sampling device must be washed clean water and wipe dry.

Good to know

Optimal electrolyte density in the battery depending on the time of year and area of ​​operation

table 2

Electrolyte freezing point depending on density

Table 3

5. Warranty

5.1. A hydrometer for electrolyte and antifreeze AET with a device for collecting liquid (a set for a motorist) is manufactured in accordance with TU U 33.2-24667973-004:2007.
5.2. Guarantee period operation 12 months from the date of sale through a retail network.



A hydrometer is a measuring apparatus used in various laboratories for measuring density and specific gravity bodies, as well as liquids. This device is also used to determine the concentration of substances in solutions consisting of two components.

The principle of operation of this device is based on Archimedes’ law, known to any physicist (any physical body, being in water, weighs the same as the weight of the water displaced by this body). The hydrometer has the form of a glass float filled with ballast, usually of metallic origin. Exist as hydrometers general purpose, and special hydrometers for petroleum products (kerosene, gasoline, diesel fuel), for electrolyte, for alcohol, for milk, whey and other liquids. With their help, the density of a particular liquid is determined, as well as the strength of a particular alcoholic drink.

To measure the conditional weight of a liquid, it is carefully poured into a glass vessel, into which the hydrometer is then carefully lowered. When the device is in the correct position, readings are taken on the scale. The weight value is taken to be the indicator opposite which the liquid level is recorded.

When working with a hydrometer, the laboratory assistant also uses a bucket with a lid. It is needed as a reservoir for working water, into which our device with the solution is immersed. The purpose of the lid is to collect a sample of the test solution.

The components of a hydrometer are a float, a measuring cup, a rod that has a main and correction scale, and a removable sinker. It turns out that without chemical glassware not enough. The measuring cup has 2 cavities - one serves to sample the solution being measured, the other to accommodate ballast, which is most often made of metal, necessary to ensure the stability of the device lowered into water. From environment The ballast is insulated with a polyethylene plug.

A car hydrometer has a special design - inside the glass tube of such a device there is not 1 float, but a certain number. Their mass is different, but the volume is completely similar. All floats have a number corresponding to a specific density. When the tube is filled with liquid, some of the floats float, some do not. If, of all the floats that float, take the one on which it is written greatest number, then it is he who shows true density test liquid.

The price of hydrometers is low; a set of hydrometers or a separate copy can be purchased at laboratory equipment stores.

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