Today we will analyze what a load plug for a battery is, what it is for and how to use a load plug.

Due to the great popularity of the article "How to check the battery", I decided to expand this topic and increase your knowledge in the field of operation and Maintenance batteries. And we will start by studying the load plug for batteries.

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

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

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

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

Types and types of load plugs for batteries.

Exists a large number of load forks. But they differ only in the range of voltage measurement with a voltmeter and the magnitude of the load.

You can also divide the load plugs by the type of tested batteries. That is, there are plugs for acid batteries and for alkaline batteries. Again, they differ only in their load.

One of clear examples load plug for alkaline batteries you see in the picture. This is a plug with interchangeable loads from 1 to 12 amps.

The reason I say that this plug is used for testing alkaline batteries is because the maximum load that is included in the plug kit creates a load current of 12 amps. And how to choose a plug, based on the magnitude of its load, we will consider below.

Unfortunately, I did not determine the type of this load plug due to the lack of markings on the case.

The following variant of the load fork is intended for testing individual cells of the battery, if the design of the battery allows it.

For these purposes, the HB-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, a plug with a voltage measurement range of at least 15 volts is required.

For example - fork E107 UHL4. 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 display. The composition has two loads of 100 amperes, with the possibility of separately connecting them 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 checked.

The scheme of the load fork HB-03 is shown in the figure.

Also, the load fork HB-03 has several additional features: automatic detection of the degree of charge of the battery; recording in memory the values ​​of measured voltages, etc.

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

The choice of 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 with a load plug voltmeter.

As I described earlier, load plugs are available for different voltage measurement ranges.

The most common surebets with a range of:

2-0-2 volts (for 1.2 V alkaline batteries)

3-0-3 volts (for 1.2V alkaline batteries and 2V acid batteries)

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

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

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

Only one condition must be observed here: the measured voltage must not exceed the maximum value of the load plug voltmeter.

2. Choice of current load.

When checking the battery with a load plug, you must correctly select the value of the current load.

During a battery load test, we physically connect the load of the plug 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 allowable discharge current recommended by the manufacturer of this battery.

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

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

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

- for acid and alkaline starter batteries from 1.0С to 1.4С

What is the current of the n-hour discharge mode? That is, this is the current, upon discharge of which the nominal voltage of the battery (for a car battery it is 12.6 V) drops to the permissible minimum value (again for a car battery it 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 Ah, you need:

I \u003d C / t \u003d 60 A * h / 20 h \u003d 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 fall 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 Ah, a plug with a current load of 100 A is used, for batteries with a capacity of 100-240 Ah, 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 plug.

The method for checking the battery with a load plug is quite simple, besides, I described it in the article "How to check a car battery".

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

Stage 1. Check 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 degree of charge of the battery according to the following table:

Stage 2. Check battery voltage under load.

We connect the load and measure the battery voltage.

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

Do not measure for more than 6-10 seconds, as this leads to heating of the load-coil and may lead to failure of the load fork itself.

In the event that the degree of charge of the battery is different from 100%, then it is necessary to full charge according to existing methods, which I will tell you in the next issues of the ELECTRON magazine. After that, check the battery again with a load plug.

If the percentage of battery charge obtained during the test without load is greater than under load, then they say the battery "does not hold the load." This means that measures must be taken to restore the capacity of the battery. And for this it is necessary to determine the cause of the drop in capacity and the feasibility of further operations to restore the batteries.

We will discuss how to determine the cause and restore the battery in the next issues of the ELECTRON magazine, so do not forget to subscribe to new issues of the magazine.

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

Checking the condition of the battery is a tricky business. After all, even a worn-out battery, in which, without load, shows normal voltage. The only way to effectively check the condition of a battery is to use a load plug. From the article, you will learn how this device works, what processes occur during such a battery test, and learn how to use the load plug correctly.

How the battery works

To check the battery, you need to understand how it works and what processes occur during discharge. Electricity is generated by a chemical reaction involving two contacts and an electrolyte. In the process of converting the electrolyte into electrical energy, its density decreases.

The lower the value, the less current the battery can deliver. Therefore, a discharged battery is not able to start the engine - the current that it generates is not enough for the starter to be able to effectively rotate the crankshaft.

A car battery is not just one device. In one case, 6 or 12 batteries are combined, connected in series, so the whole device is called a battery. Each battery consists of several blocks, including a positive and negative electrode. These blocks are connected in parallel, which increases the maximum current that the battery (battery) can produce. The performance of the battery and the entire battery depends on the state of each block.

Battery diagnostic method

The main problem that arises when checking the battery is the inability to assess the condition of individual blocks and batteries. After all, all the electrical connections between them are hidden under a rugged case. So you have to check the whole battery. To do this, you will have to remember the basic law of electrical engineering - Ohm's law, which sounds like this: the current in the circuit is directly proportional to the voltage and inversely proportional to the resistance. To do this, a load resistor is connected to the battery, whose resistance corresponds to the current and. If the battery is good and charged, then the voltage will drop hardly noticeably when the load is connected. If the density of the electrolyte, the condition of the plates or contacts of at least one battery is unsatisfactory, then the voltage drop at the battery output will be significant.

How the load fork works

The basis of the load fork is a powerful sheet steel resistor. Its resistance depends on the current. For car batteries with a capacity of 45-65 ampere-hours, it is 100 ± 20 amperes. To do this, the resistance of the resistor should be 0.125 ohms. A voltmeter is connected in parallel with the resistor, the scale of which allows you to track the change in voltage even in tenths of a Volt. For connection to a car battery, the plug is equipped with a contact and an external probe. When both probes are connected to the battery, the resistor loads the battery, providing a current in the region of 100 amperes.

The voltage of a fully serviceable and charged battery at this current does not fall below 10 volts. The cost of inexpensive models of load plugs that are suitable for testing car batteries is 400-700 rubles, so there is no point in making this device yourself.

Checking the battery with a load plug

To check the battery you will need:

• Charger;
• distilled water;
• tester;
• load plug with a current of 100 amperes and a voltmeter up to 15-20 volts.

Check the electrolyte level, top up with distilled water if necessary. Charge the battery. For information on how to do this correctly, read the article (how to properly charge the battery). 3 hours after the end of charging, the voltage at the battery terminals should not be less than 12.6 volts. Connect the load plug to the battery terminals, observing the polarity. The test time is no more than 3 seconds, otherwise the load resistor will heat up and there will be a risk of ignition of the plug. If the voltage at the battery terminals does not drop below 10.2 volts, then the battery is fully functional. A voltage drop of up to 9 volts indicates a decrease in battery capacity by at least 50 percent.

For beginners, creating a load fork with your own hands is not too difficult. However, some knowledge of the process of its collection and application is required. It is indispensable in the case of battery inspection.

With this device, you can easily measure how charged the battery itself is. It is a kind of element related to the electric circuit of considerable power. The simplest plug is equipped with a pair of clamps and a special voltmeter. As for more complicated models, their elements also include an ammeter and other devices for measuring a wide variety of vehicle parameters.

Of course, the load type of forks can be found in any specialized store, but if you have the desire and ingenuity in the process of creating it, you can limit yourself solely on your own.

How to use correctly

A homemade plug is great for measuring the amount of energy in 12-watt batteries.
However, it is also suitable for batteries with large capacities. The only difference is that more powerful option requires a pair of load springs, and the less capacious option - only one. To conduct a full check using this device you need:

• Measure the voltage at the terminals themselves, without resorting to the use of load resistances, but such an action is most appropriate to perform after at least six hours of the motor being turned off;
• The "positive" clamp is connected to the corresponding terminal, but without a spring;
• The "negative" clamp is connected to the terminal and only after that the voltmeter should show the voltage of the battery with an open circuit;
• The information received must be compared with that described in the instruction manual, and only after that it is possible to draw a confident conclusion about how low the battery is;
• In the case of a full charge, the battery is checked already under load, more precisely, using a lower load. Such a check also includes all of the above repeated actions;
• After five seconds of active testing, you can take reliable readings that a home-made device displays.

If, during the connection of the “negative” clamp to the corresponding terminal, sparks suddenly began to be born - it's okay, there is no trouble in this and this is normal. However, one should not forget that it is necessary to wrap the battery plugs themselves during the testing process. Since the clamps tend to heat up due to the energy passing through them, it is better not to touch them after taking all the necessary indicators.

Nine watts is considered an acceptable charge indicator, since other values ​​\u200b\u200bliterally “scream” about the need for either recharging or a complete replacement. It should be understood and remembered that such a check puts a certain load on the car battery, so such a too frequent load procedure has an extremely negative impact on its operation.

Do it yourself

Before directly creating a load device, first measure the voltage value of one fully charged jar of the battery. In addition, each such jar should have free access separately. It is already from the data obtained from such a measurement that one should build on a special scale, which in the future will show the charge of the car battery in the required range. However, if there is an instruction for it, then you can find out, in this way, the minimum allowable and maximum allowable charge values. This is also important.

The load plug itself must not be connected to a rechargeable battery. This is just as unacceptable as storing it next to similar devices. Therefore, the scheme for creating such a device also provides for the presence of certain knowledge of physics. First of all, the resistance of the load element of the electrical circuit is calculated, which is done using the following formula:

The R value is resistance, measured in "ohms". Accordingly, U is the voltage itself, which is measured in "V". The last value, the I value, is the direct current, which is measured in "A".

As for the power (P) of such a circuit, it can be found by multiplying the voltage value (U) by the current strength (I).

It is clear that the clamps themselves must have a huge endurance, because high current flows will flow through them. They are connected to the circuit element manually - using high-quality wires that can withstand heavy loads. All parts at the junctions with each other must be perfectly soldered using an appropriate soldering apparatus. It remains to connect a voltmeter to the finished device.

For greater ease of use, it is desirable to place all these elements on a frame with a handle that does not bend. In addition, wood and any other material that has the properties of ignition cannot serve as the material of such a frame. After the verification procedure, the room in which it took place is also fully ventilated.

Video “Checking the battery with a load plug”

The recording shows one of the methods for checking the battery using a load plug.

The load fork is an assistant to every motorist, since this device is used to check and determine the degree of charge of the battery cans, in other words, it determines the performance 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 in the first photo: a voltmeter is built into the metal case, as well as one or more load coils (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 rear surface of the instrument case, and on the second side there is a special clamp for connecting to a car battery, more precisely, to its terminals. You can also see two nuts on the back wall of the case - they serve to connect load coils of 100 amperes each.

How to test a battery with a load plug

Load plugs 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 test a car battery with a load plug, do the following:

A voltmeter value 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 control test or replaced.

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

How to make a load fork

Since the load fork is a valuable assistant to 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 need to first make sure that the battery has access to individual banks.

Then they 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 cans. After that, the scale of the device is changed to a new one. It is calibrated by applying an alternating DC voltage to the voltmeter (always in the correct polarity). The voltage supplied at the time of calibration is controlled by an exemplary instrument.
The instructions for the battery must indicate the values ​​\u200b\u200bof the rated and maximum load current. Since the result will be obtained in the SI system, then all indicators must be translated into this system.

The load resistor resistance is calculated by 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: in the formula, you need to substitute the values ​​\u200b\u200bfor one bank, and not for the entire battery.

The power dissipated in the resistor is calculated by the formula P=UI, where P is the power in Watts, U is the voltage in Volts and I is the current in Amps. In this case, the resistor must be wire-wound, and its power must be greater than that emitted from the standard edge.

The probes for the load plug must be sized 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 load fork is not yet complete.

It is necessary to connect a voltmeter in parallel with the load (a microammeter with a small resistor connected in series 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 refractory 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 desirable to be near charging batteries. After the end of the process, it is necessary to ventilate the room well.
The load plug is connected in turn to each bank.

• The resistance is calculated based on the required current strength. It is important to choose the power so that the part does not burn out.
• Resistors required power most likely will be wire parts with a ceramic core.
• As a probe, you can use a strip of steel or use nichrome parts.
• You can also use another load plug scheme - 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.

If the driver of a car is sure that there is enough fuel in the tank, but the car does not start, the first thing that comes to mind is a problem with the battery. The battery is one of the important components of the electrical equipment of road transport. Its main function is to help the starter start the engine. If the car does not start, experienced motorists recommend checking the battery. There are a lot of ways, but today we will tell you how to properly check the battery with a load plug, about the types this device, as well as how to make a load plug for batteries with your own hands.

The load resistance of the fork is in the form of a spiral.

So, a load plug for checking the battery is a device whose main functional property is to measure or discharge the battery. The design of this device is quite simple - a voltmeter and a certain number of load coils are installed in the metal case, which act as resistance. The negative (negative) electrode of the voltmeter is attached to a metal pin (it can be seen on the back of the metal case), and the positive one - to a wire of a sufficiently large cross section, which ends with a special clamp. It is the clip that is connected to the battery terminals in the process of diagnosing the latter.

Why do you need to check the battery

As mentioned above, the battery is a device responsible for starting the engine of any road transport, and it depends on its serviceability whether you drive a car or walk today. Unfortunately, buying a new battery does not guarantee that it will be in good condition, so for peace of mind, it is better to test the battery with a load plug when buying. How to check will be described below.
If you haven’t gotten around to making a load plug, then there are several other ways to check the battery without a load plug.
The main ones are:

When buying a battery, it is necessary to check it with a load plug.

• external (visual) inspection of the battery;
• electrolyte level measurement;
• electrolyte density diagnostics using a hydrometer;
• check using a voltmeter as well as a multimeter.

How to make the right choice

A diverse range of load forks often baffles those who want to buy this device. How to understand which battery test plug is better, how not to make a mistake with the choice?
First of all, it is worth noting that, despite the wide range, plugs differ in several factors: measurement range, load, battery type.
Types of load plugs for testing batteries can be classified according to the following principle:

• measurement range;
• load value;
• type of battery: acid or alkaline.

In addition to the above types, load forks can be classified according to the type of indicator. In modern versions of this device, liquid crystal indicators are already mounted. It should be noted that the answer to the question, how much does a load plug for a battery cost, will also depend on functionality some other type of device.

How to use the device

Checking the battery voltage with a load plug without load

It is no secret that novice drivers, and especially female drivers, are wary of any problems related to the internal structure and components of the car. However, we want to reassure you that working with this device is quite simple.
So how to use the battery load plug?
There are two options for checking the battery with a load plug. Let's briefly dwell on each method of how to test the battery with a load plug.

Test without load

Before checking the battery with a load plug, disconnect the terminals and wait 6 hours.

For this diagnosis, it is necessary to preliminary work- disconnect the battery from charging and be sure to wait for at least 6 hours to pass. Then the “positive” clamp of the device should be connected to a similar battery terminal, and the “minus” pin should be touched to a similar terminal. Take the indicator readings. This way of working with the plug will show you the state of charge of the battery:

• with a voltmeter value in the range of 11.5–11.8, it shows the battery is completely discharged;
• readings ranging from 11.8-12.1 indicate that 25% of the charge remains;
• numbers 12.1–12.3 - it means that the battery is half charged;
• indicators 12.3–12.6 - the battery has a 75% charge;
• 12.6–12.9 - these numbers indicate a full (100%) battery charge.

Load test

Checking the battery voltage with a load plug under load

Battery diagnostics under load should be carried out for no more than 5 seconds.

This is the next step in diagnosing the battery. It is no different from the first method, the only exception is that you connect the appropriate load to the load plug. The steps are the same for testing without load. Please note that diagnostics must be carried out for no more than 5 seconds. If the indicators on the plug indicator show more than 10.2 volts, it means that the battery is charged, otherwise. If the results of the first and second diagnostics are strikingly different, we can conclude that the battery is faulty.

Making a load fork yourself

Precisely because the load plug for the battery has a rather big price, experienced motorists prefer to use a plug own production. The whole process of how to make a load plug to check the battery can be divided into the following steps:

• determine the voltage in one cell of your battery in a fully charged state. This can be done empirically, or read in the battery manual. An important factor is to make sure that you have access to all banks;
• using a microammeter and a resistor, graduate the future plug;
• calculate the resistance of the resistors;
• connect the probes and solder the mounting points well. Remember to indicate the polarity of each probe;
• fix all parts of the future plug in a metal case.

We hope that we helped you at least a little to study the topic “Car battery load plug”, and now you can choose or make your own exactly the device that you need.