Load fork current. Load fork - timely detection of battery failure

When using a battery, it is often necessary to check the battery. Eat different ways for different purposes, but the first thing to use is a load fork. This device will allow you to spot charging problems in time, which could lead to problems on the road in the future. This means that checking the battery, in particular with this device, is one of the conditions for safe operation of the car. Therefore, it is important to master this method.

This is a battery testing device. It does not check all the parameters of the battery, but it allows you to obtain enough information about the condition of the battery so that you can come to your senses in time and replace this important component of any car. It is possible to purchase a product, including a digital plug, or you can make a load plug yourself.

How to check correctly

Now you will learn how to test the battery with a load fork. This is an important skill because it allows you to get almost all the necessary information about the battery. There is nothing difficult about checking the battery with a load fork. Everything is done according to the instructions. There is no need to remove the batteries for this procedure. The fork can even be placed under the hood. Fortunately, this testing device is not large. Before taking measurements, check the circuit for leaks. Also inspect the battery visually. That's why it's also important to know how to test a battery without a load plug. When checking, do not leave both devices unattended.

No load

The plug is connected to the battery. The next step is to measure the open circuit voltage. This is normally at least 12.7 V if the battery is fully charged. If the indicators are as follows, then it is possible to proceed to checking the battery already under load. If not, then the device should be charged first.

Under load

Here's how to use the load fork:

1. Connect the plug to the battery.
2. The fork forms the load. The latter lasts from five to six seconds.
3. They receive readings and record them.
4. Check the data in the table with battery standards.
5. They draw conclusions.

DIY battery load fork

Today there is different models for checking car batteries. However, if you want to save money and craft, it is possible to make such a fork yourself. Products made by handicraft are inferior in appearance industrial, but in terms of functionality - no.

Here's how to make a load fork:

1. Take a spiral. It could be a coil from an old electric stove, or something else. An avid motorist should rummage around in the garage; he'll probably find something. Or, if there is nothing like that there, perhaps there is unnecessary equipment in the house that can be disassembled for such a reason.
2. Such a part is rolled into several layers, that is, wire strands. This is done in order to achieve a resistance of 0.1 - 0.15 Ohms. The result is a sort of small element of resistance, but it must be properly connected to other parts of the device, otherwise it will be useless.
3. Now you will need a 21 Watt car light bulb (for example, from turn signals). You will also need a battery up to 15 Volts. The result is a homemade resistance. The latter is either secured with a nut and screw, or soldered. Add a multimeter with a range of 10 Amps. Regular will do option from the store. The main thing is to be confident in the functionality of the device. The latter determines whether it will be possible to assemble a working fork capable of giving accurate readings. And the owner’s awareness of the condition of the battery and, possibly, safety on the road will depend on these readings.
4. Now the entire chain is assembled. The connection is made in series.
5. Attach the clamps to the terminals of the car battery.
6. They look at the multimeter and get readings. It should be around 1.78 Amps.
7. The multimeter is removed.
8. Reconnect the entire circuit.
9. Measure the voltage on the spiral. It should be about 197 millivolts.
10. Calculate resistance using Ohm's law. The voltage is divided by the current, and you get about 0.11 ohms (if the numbers are the same as above).
11. Now the plug is connected to the battery for about five seconds. First connect the multimeter. A direct current of 20 Volts is supplied.
12. All that remains is to take readings and draw conclusions.

It is important that all components of the homemade device are in good condition. If at least one of these is of poor quality, all measurements may be inaccurate. So you either need to make a fork no worse than an industrial one, or buy one in a store.

In conclusion, it is worth noting that checking the battery with a load fork is not a difficult task, but it is important. It is important to know the application features and how to check the battery in this way. Just in case, it’s worth familiarizing yourself with how to make such a device yourself. And then battery problems will be noticed in time. And this is sometimes vitally important.

Load fork video

Today we will look at what a battery load fork is, what it is intended for and how to use a load fork.

Due to the great popularity of the article “How to check the battery” I decided to expand this topic and increase your knowledge of battery operation and maintenance. And we'll start by studying the load plug for batteries.

The load plug is designed to determine the state of charge (discharge) of the battery and is a good assistant for determining the health of the battery when testing it.

Also, the built-in voltmeter of the load plug can be used when diagnosing elements of the vehicle’s on-board network.

In general, the load plug is a voltmeter, parallel to which a load made in the form of a spiral is connected. The load can be disconnected if necessary, and the plug can be used as a voltmeter.

The electrical circuit of the simplest load fork is shown in the following figure.

Types and types of load forks for batteries.

There are a large number of load forks. But they differ only in the voltage measurement range with a voltmeter and the load size.

You can also divide the load forks according to the type of battery being tested. That is, there are plugs for acid batteries and for alkaline batteries. Again, they differ only in the load they contain.

You can see one of the striking examples of a load plug for alkaline batteries in the figure. This is a plug with interchangeable loads from 1 to 12 amps.

The reason I say this plug is used to test alkaline batteries is because the maximum load included with the plug produces a load current of 12 amps. We’ll look at how to choose a fork based on the size of its load below.

Unfortunately, I have not determined the type of this load fork due to the lack of markings on the body.

The next version of the load fork is designed for testing individual battery cells, if the battery design allows it.

For these purposes, the NV-B fork is used. It has a voltmeter with a maximum voltage measurement range of 3-0-3 volts. The current load created by this plug is 100 amperes.

This plug can be used to test 1.2 volt alkaline batteries and to test 2 volt acid batteries.

To test 12-volt car batteries, you need a plug with a voltage measurement range of at least 15 volts.

For example, the E107 UHL4 plug. It has a voltmeter with a scale of up to 20 volts, a load resistance of 0.1 Ohm, that is, it is designed for a load of 100 amperes.

The most modern version of the load fork is the HB-03 fork. It has an electronic voltmeter with a liquid crystal indicator. It contains two 100 ampere loads, with the ability to connect them separately to the plug.

When connecting one load (total current load - 100 amperes), batteries with a capacity of 15 to 100 Ah are tested. When connecting two loads (total current load 200 amperes), batteries with a capacity of 100 to 240 Ah are tested.

The diagram of the NV-03 load fork is shown in the figure.

Also, the load fork NV-03 has several additional functions: automatic detection battery charge level; recording the values ​​of measured voltages into memory, etc.

Attention! The NV-03 plug has the ability to calibrate a voltmeter and a range of temporary voltage measurements under load. Therefore, before use, it is advisable to make sure that the plug is calibrated.

Selecting a load plug depending on the type of battery.

So, we are faced with the question: “How to choose a load fork?”

1. Determining the range of measured voltages using a load plug voltmeter.

As I described earlier, load forks are available in different voltage measurement ranges.

The most common forks with the range:

2-0-2 volts (for alkaline batteries with a voltage of 1.2 V)

3-0-3 volts (for alkaline batteries with a voltage of 1.2 V and acid batteries with a voltage of 2 V)

0-15 volts (for 12 V acid and alkaline batteries)

0-20 volts (for 12 V acid and alkaline batteries)

0-30 volts (for 24 V acid and alkaline batteries)

Here only one condition must be observed: the measured voltage should not exceed the maximum value of the load plug voltmeter.

2. Selection of current load.

When testing a battery using a load fork, you must select the correct current load value.

When testing a battery under load, we physically connect the plug load to the battery, creating a discharge current in the resulting circuit.

For a better test of the battery, this current should have a maximum value, but not exceed the permissible value of the discharge current recommended by the manufacturer of this battery.

Of course, not all manufacturers provide the value of the maximum permissible discharge current for their batteries (not to be confused with the starter current!), and not every car owner will open the passport for the battery and look for the value of this current.

- for traction alkaline batteries- 3-hour discharge current (0.33C, where C is the nominal battery capacity in A*h);

- for traction acid batteries- current of 1-hour discharge mode (1.0C);

- for starter batteries, acid and alkaline from 1.0C to 1.4C

What is the n-hour discharge current?? That is, this is the current, when discharged, the rated voltage of the battery (for a car battery this is 12.6 V) will drop to the permissible minimum value (again for a car battery this is 10.2 V) for a given period of time (n-hours).

To determine the n-hour discharge current, you need to divide the battery capacity indicated on it by the discharge time.

For example, in order to find out the 20-hour discharge current of a battery with a capacity of 60 A*h, you need to:

I = C/t = 60 A*h/20 h = 3 A.

This means that the manufacturer guarantees that when this battery is discharged with a current of 3 A for 20 hours, its voltage will not drop below 10.2 V.

Thus, for car batteries, the current generated by the load plug should be within 1-1.4 of the capacity specified by the manufacturer.

In practice, for batteries with a capacity of 15-100 A*h, a plug with a current load of 100 A is used, for batteries with a capacity of 100-240 A*h, a plug with a current load of 200 A is used.

Therefore, the most common load plugs for car batteries have a current load of 100A.

Checking the battery with a load fork.

The method of testing a battery with a load fork is quite simple, and I also described it in the article “How to test a car battery.”

However, I consider it necessary to state it here again:

Stage 1 Checking the battery voltage without load.

To do this, disconnect the load from the load plug voltmeter. And using a voltmeter, we measure the voltage on the battery.

In this case, we determine the battery charge level using the following table:

Stage 2. Checking battery voltage under load.

We connect the load and measure the battery voltage.

We take readings from the load fork voltmeter at the end of the fifth second of measurement. The battery charge level is determined using the following table:

You should not take measurements for more than 6-10 seconds, as this leads to heating of the load-spiral and can lead to failure of the load fork itself.

If the charge level of the battery is different from 100%, then it is necessary to fully charge it using existing methods, which I will tell you in the next issues of ELECTRON magazine. After this, check the battery again using a load fork.

If the percentage of battery charge obtained when testing without load is greater than under load, then the battery is said to “not hold the load.” This means that it is necessary to take measures to restore the battery capacity. And to do this, it is necessary to determine the reason for the drop in capacity and the feasibility of further operations to restore the batteries.

We will talk about how to determine the cause and restore the battery in the next issues of the ELECTRON magazine, so don’t forget to subscribe to new issues of the magazine.

And now a detailed video about working with a load fork,

All car owners understand that the main element of any car is the battery, which ensures the operation of all electrical systems and devices. But, like any power source, the device can fail. In this case, maintenance will be required. One of the effective diagnostic methods is to check with a load fork.

Basic Concepts

A load fork is a device that analyzes the operation of car batteries. The device monitors the open circuit voltage, the batteries under load at the output points, and the overall performance of the battery. The device includes a voltmeter, resistance coils, and in some cases an ammeter. The scope of application of the device is not limited to car batteries; it can be used to take readings from any part of the electrical circuit.

This is a small device in a metal case with several resistances and a voltmeter. On one side, a thick wire is connected to the voltmeter, on the other there is a clamp for connecting the positive electrode of the device to the battery. The negative terminal is connected to a metal pin. The resistance coils are connected with two nuts. The load on each spiral is calculated at 100 A of electric current. Clips on the wires are necessary to connect them to the battery terminals.

There are quite a few types into which the load fork is divided. The device diagram is the same for everyone and is nothing complicated. An important difference between the devices is the voltage measurement range and load rating. Alkaline batteries and acid batteries use different plugs.

How to use the load fork?

Before using the device, the engine must be idle for at least 6 hours; you can check it after overnight parking. The procedure is carried out in two stages. It should be taken into account that 12-volt batteries can be tested using one spiral, and for larger capacities two are used.

A device with an unconnected load is connected to each terminal of the element. The positive terminal is connected to the same charge of the battery terminal, after which they work with the negative elements. The voltmeter readings are recorded.

Meaning of indicators and action plan

• The battery is 100% charged - 13 W.
• Battery malfunction or discharge - 11.5-11.8 W.
• 75% charge - 12.3-12.6 W.
• At 50% the data will be between 12.1 and 12.3 watts.
• 25% (almost complete discharge) - 11.8-12.1 W.

If after checking it turns out that the battery is fully charged, you need to perform the same actions as additional measurements, only you need to turn on the load connections.

Sequence of work:

• the terminal is cleaned;
• the load plug is connected with the correct polarity;
• voltage is measured;
• The resistance is set according to the battery volume.

The load fork is pressed against the battery terminal until it stops for a short time (up to 5 seconds). The battery plugs must be wrapped when performing these steps. If sparks start when you touch the negative terminal, it’s okay - this is normal. However, the heated pin should not be touched with your hands between measurements.

Identifying indicators

The serviceability and full charging of the battery is indicated by the 9 W mark. Indicators less than this figure indicate that the battery is incomplete or broken. In this case, it is necessary to charge and repeat the measurement procedure.

If the battery is in good condition, the indicators should return to normal; if this does not happen, detailed diagnostics or battery replacement is required. You should not use the load fork for preventive purposes and very often - such actions can damage the battery.

Making a device yourself

So, the load fork is powerful tool with voltmeter DC and two probes. Of course, this type of device can be found in any specialized store, but with desire and ingenuity, a self-created load fork will become an equally useful device.

A homemade plug is good for measuring energy in 12-watt batteries. Before you start creating the device, you need to measure the voltage value of one fully charged battery jar. Each such jar must have free access. The data obtained is necessary to compile a scale that will show the car’s battery charge in the desired range in the future.

Next, you will need to turn on the microammeter together with the resistor. It is necessary to monitor the resistance; it should be slightly greater than the voltage of one of the battery banks. The scale of the device is changed by supplying a voltmeter with an alternating direct current voltage in the required polarity, which is controlled by a reference device.

Formulas for calculations

The instructions for the battery indicate information about the minimum and maximum permissible charge values, you need to know them. The design of the device requires some knowledge of physics, namely the formula for the resistance of the load element electrical circuit. It is determined by the formula: R=U/I.

Here R is defined as the resistance value (Ohm), U stands for voltage (V), and current stands for I (A). The power (P) of such a circuit can be found by multiplying the voltage (U) by the current (I). The clamps must have a long endurance, because a large current will pass through them. They are manually connected to the resistor with high-quality wires that can withstand heavy loads.

All parts at the joints must be well soldered using a soldering apparatus. Now you need to connect a voltmeter to the homemade load plug (you can use a microammeter with a small resistor as it). The terminals are marked with the same polarity as on a working voltmeter. The connection points are isolated.

You can build a frame to mount the device on it for ease of use. The materials used for this purpose are exclusively non-flammable, in the best option Metal will do. In this way, a do-it-yourself load fork is created.

Installation Rules

When installing, it is important to follow the basic rules:

• the device is connected to the battery only in the disconnected state;
• It is prohibited to store the plug near other battery-powered devices;
• after work, the room is thoroughly ventilated;
• connection to each jar is carried out separately;
• it is necessary to monitor the current power so as not to damage the elements;
• steel or nichrome is used for clamping;
• The equipment does not connect for long, especially homemade ones.

The task performed by a digital load fork is no different from conventional device. However, its important feature is the ultra-precise measurement results displayed on the equipment display.

Features and disadvantages of the device

For many years, the heavy load method has been used to test the performance of lead batteries. Devices capable of drawing a current of hundreds of amperes from a battery and measuring the voltage under such a load are still being produced. The voltmeter scale is painted in several colors. When the arrow is in the green area, the battery is considered to be in good condition, red is a sign that the battery needs to be replaced.

The popularity of the fork is due to the qualitative identification of indicators. However, it is not possible to check the battery capacity. Therefore, it is extremely difficult to predict the service life of a product in this way. Another fact that needs to be taken into account: the plug takes a significant percentage of the charge from the battery, so it cannot be used often.

Effectively, such devices help to identify a defective individual bank from a general assembly, and also make it possible to check the battery’s charge to a certain voltage and the ability to withstand the operating current of the battery.

The most accurate data is obtained when diagnosing new battery devices. It is recommended to carry out testing at a time when the electrolyte temperature is positive from +10 to +25 °C. It is not at all necessary to throw away spoiled batteries; there are enough recycling points for such devices. The replacement resistance must match the capacity and type of battery.

A load fork is an assistant for every motorist, since this device serves to check and determine the degree of charge of the battery cells, in other words, determines the performance of the car battery. The device is a high-power load resistor with a voltmeter and two probes. This is the simplest option, but there are also more complex devices, for example, with an ammeter and the ability to measure various parameters of the entire electrical circuit of the machine.

Automotive stores sell ready-made devices that look like the first photo: a voltmeter is built into a metal case, as well as one or more load spirals (or resistances). A thick wire is connected to the positive output of the voltmeter, the negative one is connected to a metal pin on the back surface of the device body, and on the second side there is a special clamp for connecting to a car battery, or rather to its terminals. On the back wall of the case you can also see two nuts - they are used to connect load spirals of 100 amperes each.

How to test a battery with a load fork

Load forks of the type described above are suitable for checking the condition of 12-volt batteries (in this case, one load coil works) or high-capacity batteries (both coils work).

To check a car battery with a load fork, you must perform the following steps:

A voltmeter reading of 9.0 Volts is considered a good result - this means that the battery is in good condition. Other results indicate that the battery needs to be charged with a test measurement or replaced.

Since this method of testing the condition of the battery places some stress on the battery, you should not use the load fork too often.

How to make a load fork

Since a load fork is a valuable assistant for any motorist, but such devices are quite expensive in stores, it makes sense to make the device yourself.
To begin with, from the user manual you should determine the voltage of one fully charged battery bank (specifically for this model). You also first need to make sure that the AKB has access to individual banks.

Then take a microammeter and turn it on together with a resistor. In this case, the resistance should be slightly greater than the voltage of one of the battery banks. After this, the device scale is changed to a new one. It is calibrated by supplying an alternating direct current voltage to a voltmeter (necessarily in the required polarity). The voltage supplied at the time of calibration is controlled by a standard device.
The instructions for the battery must indicate the values ​​of the rated and maximum load current. Since the result will be obtained in the SI system, then all indicators must be converted to this system.

The resistance of the load resistor is calculated using the formula R=U/I, where I is the current in Amperes, U is the voltage in Volts and R is the resistance in Ohms. Important: you must substitute the values ​​for one jar into the formula, and not for the entire battery.

The power released by the resistor is calculated using the formula P=UI, where P is the power in Watts, U is the voltage in Volts and I is the current in Amperes. In this case, the resistor must be wirewound, and its power must be greater than that released from the standard edge.

The load plug probes must be large enough to withstand the current flowing through the resistor. They are connected to the resistor using wires, also made of a material that can withstand the load current. All connections must be well soldered.
At this stage, the loading fork is not yet complete.

It is necessary to connect a voltmeter in parallel with the load (a microammeter with a small series-connected resistor can be used as it. The polarity is marked on the probes - the same as on the switched on voltmeter - and the connection points are isolated.

All parts can be mounted on a rigid frame with a handle. It is necessary to use dielectric and fireproof materials. The distance between the parts should be equal to the distance between the terminals of the battery cans.

It is important to remember that the load plug should not be connected to the battery being charged and it is not even advisable for it to be located near batteries being charged. After completing the process, it is necessary to ventilate the room well.
The load plug is connected to each bank in turn.

• Resistance is calculated based on the required current. It is important to choose the power so that the part does not burn out.
• Resistors of the required power will most likely be wire parts with a ceramic core.
• You can use a steel strip as a probe or use nichrome parts.
• You can also use a different load plug design - with four contacts instead of two (two contacts per terminal).
• It is better to make the ends of the contacts pointed in order to push through the layer of oxides.
• It is important that the load plug must be connected for a strictly defined time, no more, no less.

Drivers who independently maintain their car are often interested in how to make a battery load fork with their own hands. It should be said right away that to perform such work you need to have at least a little experience working with electrical equipment. Today, no one will argue that this device plays an important role in the proper maintenance and operation of the car battery. From proper care This device largely depends on its service life on the car.

All interested car enthusiasts will be able to learn how to make a load plug for a battery with their own hands, and then decide what to do, make it yourself or purchase a finished product in retail chains. In any case, such a device will be a useful acquisition for your garage and car. If you have a certain supply of radio components, know how to hold a soldering iron in your hands and want to have such a device at your disposal, then read the article to the end and get down to business.

For what purposes is this device used?

It is simply impossible to carry out a complete and high-quality check of the working condition of the battery without this device. The load plug is used to determine the degree of charge of the battery without a load, as well as with a load corresponding to the battery being tested. Such checks are not done very often, since when checking under load, a significant amount of current is consumed, which can affect the condition of the battery.

The industry produces such plugs with a set of different loads in order to be able to test batteries of different capacities, but when making a load plug yourself, it is enough to select it in accordance with the battery being tested. Passenger cars do not have a very wide range of battery parameters, so such a device will be useful even after replacing the car with another model.

A few words about its use

The load fork usually consists of several elements, these can be the following parts:

• Handle for holding it;
• Voltmeter for measuring the voltage of the battery being tested;
• Probes for connecting to the terminals of the battery being tested;
• Additional resistance.

Sometimes there are devices in which, in addition to a voltmeter, . Use a plug to check the condition of the batteries intended for use in systems with a power supply voltage of 12 Volts.

There are simple rules for its correct use:

• The battery should be checked without load after it has been left “settled” for at least 6 hours;
• First of all, you should connect the positive terminal and only then the negative terminal. During such a connection, sparking is possible, so the battery plugs must be closed;
• To carry out a test with full load, you need to connect an additional resistance. The measurement is carried out for approximately 5 seconds, after which you need to compare the obtained data with the recommendations in the battery operating instructions.

When checking under load, the clamps of the load fork heat up, so you should work very carefully to avoid burns.

About the manufacturing stages

First of all, you need to prepare the necessary materials. The main element of any load fork is a measuring device, in this particular case it will be a voltmeter. It’s good if you find or manage to purchase one with a scale of up to about 20 Volts, which is most convenient for taking measurements, otherwise you’ll have to calibrate it yourself.

When making a new scale, you will have to carefully disassemble the voltmeter. To determine the voltage, you need an additional tester or multimeter, which will be used to monitor the currents passing through a calibrated device. To do this, additional resistances are connected in series with it and measurements are taken. After plotting the readings on the new scale, it is carefully placed in the voltmeter.

From the battery characteristics, you should select the current and voltage parameters under load. This is necessary to determine the parameters of the additional resistance. They can be determined using formulas.

To determine the resistance, it will be R=U/I, where R is the resistance of the additional resistor, U will be the voltage, and I will be the current under load. After this, the dissipated power of this resistance is determined using the formula P=UI. The resistance power should be taken slightly higher than that obtained after calculations. The resistance must be wire.

To make probes, you should use multi-core insulated wires with a diameter of at least 6 mm; they can be connected to the battery using powerful alligator clips. For placement measuring instrument, probes and an additional resistor, it is best to use a PCB plate; it does not conduct current and can withstand high temperatures. For ease of use of the loading fork, a handle is attached to the plate. After this, the load fork is ready for use.

As can be seen from the story, there is nothing complicated in this matter. We told you how to make a battery load fork with your own hands, and you can use this as the basis for your design. There can be many options for its manufacture, it depends on the available parts and the imagination of the manufacturer.