How to connect a voltmeter in a car and use it correctly

Drivers of cars and trucks are interested in how to connect an ammeter and voltmeter in a car. The need to install these indicators is explained by the desire to have full control over the condition of the battery and generator set. Most modern cars and previously produced ones do not have such indicators installed by the manufacturer. True, in cars with on-board computers, it is possible to control the voltage in the car’s circuits; in other models, the owners install the devices.

How to connect an ammeter and voltmeter in a car is especially interesting for owners of used cars, since many components and assemblies, including the generator set, are already quite worn out, so they may not work properly. The warning lamp only signals the absence of on-board voltage, and this is clearly not enough. For example, if you do not notice the increased charging voltage of the battery in time, this can lead to its failure.

About the functions performed by these pointers

Each control or measuring device installed in the instrument panel of the car informs the driver about the performance of a certain vehicle system. This allows you to operate the machine without compromising its technical condition. However, the electrical supply system of many cars does not have the ability for such control. Car owners try to solve such problems on their own by installing an ammeter or a voltmeter, and some owners install both of these indicators.

An ammeter installed in an electrical circuit will indicate the electrical current consumed by the system. Using these data, you can judge the battery charging process and promptly identify and eliminate problems that arise. The voltmeter also allows you to keep this process under the control of the driver, which increases the service life of electrical equipment. Here are the main reasons for installing these devices on a car.

What products are used?

Some time ago, finding and installing such a device was a big problem. Motorists installed ammeters from trucks on their cars, and those drivers who were familiar with radio electronics selected the measuring instruments themselves. The first domestic cars in which the voltmeter took its permanent place on the instrument panel was the VAZ 2105, and a little later they appeared on other models.

Today such a problem does not exist, since there is a large selection of such products in retail chains. You can install an electronic clock in the panel, which simultaneously shows the voltage of the on-board network along with the current time. There are electronic tachometers, which, after pressing the desired button, perform the functions of a voltmeter. Such devices do not cause any particular problems for owners.

Also today, automobile ammeters and voltmeters are available for sale, and individual drivers independently adjust the devices that are used in radio-electronic devices. Installing such indicators is fraught with some difficulties, since it is necessary to select shunts for them, calibrate or manufacture new scales. Therefore, we will not dwell on this.

How to install such indicators?

Let's assume that you managed to purchase an ammeter or voltmeter intended for use in cars; now let's look at the process of installing them. It is worth recalling the features of connecting them to electrical circuits.

The ammeter is connected only in series between the current source and the consumers, and the polarity of the connection must be observed, plus from the source to the plus of the device, and so on. The voltmeter is connected only in parallel to the power source, also subject to polarity.

Connection diagrams and methods

The question often arises of how to connect an ammeter, in series or in parallel. Connecting the device in question into an electrical circuit break is not difficult. For safety reasons, this procedure is performed when the power source is turned off. You need to make sure in advance that the maximum current will not exceed the permissible values ​​of the device. Such scales are duplicated in the accompanying technical documentation. When the supply voltage is applied, readings are taken. You need to wait until the needle stops oscillating. When it moves in the opposite direction, the polarity of the connection changes. If the current is too high, additional shunting is used.

The connection diagram of the device can be direct or indirect. In the first case, the device is directly connected to the electrical circuit between the power source and the load.

Before connecting the device, you must consider:

• direct or alternating current in the electrical network;
• Is the polarity of the device correct?
• the arrow of the device should be located beyond the middle of the scale;
• limits for measuring the maximum possible current surges in the circuit;
• whether the external environment meets the recommended indicators;
• Is the measurement location free from vibration?

Connecting the device

In DC circuit

Direct current can pass through different electrical circuits. As an example, we can cite all kinds of chargers and power supplies. To repair such devices, the technician must have an understanding of how the ammeter is connected to the electrical circuit.

At home, such skills will also not be superfluous. They help a person who is not too keen on radio electronics to determine for himself, for example, the time it takes to charge the battery from a camera.

To conduct the experiment, you will need a fully charged battery with a nominal voltage of, for example, 3.5 V. In addition, you need to use a lamp of the same rating to create a series circuit:

• battery;
• ammeter;
• bulb.

The entry that is marked on the measuring device is recorded. For example, a lighting fixture will consume 150 milliamps of electricity, and the battery has a capacity of 1500 milliamp-hours. Therefore, it will work for 10 hours, delivering a current of 150 mA.

Connecting to the charger

The question often arises of how to properly connect an ammeter to a charger. When using a charger, the need arises to measure the current. This will make it possible to control the process of accumulating electricity by the battery, and avoid overcharging and undercharging. As a result, the service life of the battery will increase significantly.

When operating a large number of technical devices, it becomes necessary to control the current strength. The ammeter needles or indicators on the monitor of a discrete device will show the operator such a physical parameter. The measurements taken are needed to maintain the operating condition and to signal the occurrence of an emergency.

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Connecting the ammeter

Let's start with the fact that work can only begin after the battery is disconnected. Significant current flows through this device, so you need to select wires of the appropriate cross-section. It should be connected to the wire gap that supplies power to the ignition switch. Tips should be installed and crimped with pliers on the ends of the wires, otherwise the connection point will heat up due to poor contact.

After installing the wires, check that the connections are correct. To do this, turn on the load, for example, low or high beam. The ammeter should show a discharge; if it shows the opposite value, then the connection wires should be swapped. Next, you should start the engine and make sure that the battery is charging.

Pinout of the dashboard of VAZ2113, 2114, 2115

There are 26 contacts on the VAZ-2114 instrument panel, each of which is responsible for the operation of the indicators of this panel. If a plus is supplied to the panel, then each contact displays information about the state in which the car is currently located.

White block (X1)

Red block (X2)

• Housing (weight) - black
• To ambient temperature sensor - cyan-magenta
• Tachometer (low voltage input from ECU) - brown/purple
• Fuse F16 (to terminal 15 of the ignition switch) - orange
• Tachometer (high voltage input from coil) - yellow
• Housing (weight) - black
• To fuse F3 of the mounting block (+battery) - white-purple
• Instrument lighting control - white
• Coolant temperature sensor. - green-white
• Turn signal RIGHT - blue
• To fuse F10 of the mounting block - brown
• Turn signal LEFT - blue-black
• Brake fluid level - pink-blue
• Check Engine Light to ECU Controller - White-Purple
• To the trip computer - brown
• To the ECU controller - pink and black
• Speed ​​sensor - gray and yellow
• To the fuel gauge sensor - orange
• To the fuel gauge sensor - pink
• To the parking brake switch - brown-blue
• Fuse F14 of the mounting block - green-black
• Alternator terminal "D" through fuse panel - brown and white
• Hazard switch
• Oil pressure sensor - blue
• To terminal “50” of the ignition switch - purple

In addition, special indicators and signal sensors are installed on the instrument panel, and the panel itself is controlled by a special electronic unit. Having disassembled the instrument panel, you can see that there are two pads inside it: red and white. And all inputs, outputs and fuses are connected to the plug. If the sensors fail, they will need to be replaced. It is also better to replace damaged or oxidized wires. Indicator lights, like any other, sometimes burn out. Undoubtedly, they need to be replaced with whole ones. Along with them, the lamp sensor often burns out.

VAZ 2114 instrument panel connection diagram

1. rear window heating switch;
2. rear fog lamp switch;
3. switch for headlights and direction indicators;
4. mounting block;
5. wiper switch;
6. fog light switch;
7. on-board control system display unit;
8. instrument panel harness block to additional harness;
9. instrument cluster;
10. instrument panel harness connector to the on-board computer harness;
11. instrument panel harness connector to the ignition system harness;
12. instrument panel harness connector to the side door harness;
13. fuse 16 A;
14. fuse 16 A;
15. ignition switch;
16. lighting switch;
17. heater electric motor;
18. additional resistance of the heater electric motor;
19. ignition switch unloading relay;
20. rear fog light relay;
21. starter relay;
22. socket for connecting a portable lamp;
23. cigarette lighter;
24. instrument panel harness connector to the glove compartment lamp wiring harness;
25. illuminator;
26. illuminator;
27. illuminator;
28. heater switch;
29. instrument lighting regulator with rheostat;
30. brake light switch;
31. horn switch;
32. hazard switch;
33. heater control lamp;
34. fuse 16 A;
35. seat heating relay;

Another variant of the connector pinout diagram

1. checking the brake fluid level indicator. If you apply +, the brake light will light up. You can connect it to the red wire of the ignition switch, then, just like on 2110/2114, the lamp will be checked when the starter is turned on.
2. Hazard warning lamp will light up when + is applied.
3. high beam lamp, connect to the green-black wire.
4. fuel level indicator, connect to the pink-red wire.
5. to the speed sensor.
6. speed signal output to the on-board computer. If there is one, then take the speed signal from this contact.
7. Brake fluid level indicator, connect to the pink-blue wire near the lamp above the cigarette lighter. In the VAZ-2107, the lamp works the other way around: the sensor connects the lamp to ground and it lights up. You will have to either leave the lamp where it is, or in the new device, solder the lamp to + and swap the diodes (in this case, to check the lamp, pin 1 must be connected to ground, for example, to the parking brake lamp), or remove the black wire from the sensor on the tank, and connect instead the orange one from the EPHH unit, or the blue one from the ignition coil, while the diode in the wiring (between the beard and the glove compartment) must be disconnected; if this is not done, there will be a short circuit.
8. left turn lamp, connect to the blue-black wire of the steering column switch block.
9. Right turn lamp, connect to the blue wire of the steering column switch pad.
10. instrument lighting, connect to the white wire.
11. ground, connect to the black wire.
12. power supply of devices, connect to the orange wire.
13. if the device is simple (without microcircuits, etc.), then connect it to the blue-red wire (fuel reserve lamp), if there is a display under the tachometer, then connect it to the temperature sensor (take from a VAZ-2114, one contact to the device, the other to ground, place it either in the passenger compartment or in the engine compartment, but far from the engine and so that the wind does not blow).
14. ground, connect to the white-black wire.
15. low-voltage tachometer input (from the ECM), connect to the brown-blue wire.
16. high-voltage tachometer input (from the coil), connect to the brown-blue wire.
17. If there is a display under the speedometer, then connect it to the red and white wire at the brake light switch.
18. coolant temperature gauge, connect to the green-white wire.
19. outdoor lighting lamp, connect to the yellow wire.
20. carburetor choke cover lamp, connect to the gray-orange wire.
21. go to the ECM lamp. If the machine is injection, then connect one of the contacts to the orange wire, and the other to the remaining one.
22. go to the ECM lamp. If the machine is injection, then connect one of the contacts to the orange wire, and the other to the remaining one.
23. power supply of devices, connect to the orange-blue wire.
24. handbrake lamp, connect to the brown wire.
25. battery charge lamp, connect to the brown-white wire.
26. low oil pressure lamp, connect to the gray-blue wire.

The simplest option

Those who don’t want to bother with cutting plastic in the interior, wiring and other joys associated with a voltmeter can take the path of least effort. We are talking about exactly the same devices that work through the cigarette lighter. Yes, they have an error of about 0.1-0.2 V, but this is not so critical, and in the most famous Chinese store, you won’t have to pay more than 400 rubles.

Most of these options come with a built-in thermometer (takes data from inside the cabin), but this additional function is useless (you may not agree with us). However, if you search, you can find options where, in addition to voltage and temperature (or without it at all), there are 1-2 USB ports. But this is really convenient.

If you are interested in such options, write in the comments - we will compile a selection of trusted sellers.

Publication date: January 09, 2022. Category: Motor vehicles.

Any motorcycle owner periodically has to check the voltage of the on-board network (usually using a multimeter). This must be done to control the operation of the generator and relay regulator; as well as the condition of the battery. If you make a simple tuning of your bike and install a voltmeter for the motorcycle, you can constantly receive information about the voltage of the on-board network. The variety of these devices (in terms of price, method of mounting and connection) allows such useful modifications to be made to the vehicle, even without having special technical skills or deep knowledge of electrical engineering.

Voltmeter in the cigarette lighter socket

For owners of motorcycles with a cigarette lighter socket (standard or installed independently), the easiest way to monitor the voltage of the on-board network is to install a ready-made measuring device specifically designed for installation in this socket. The choice is quite wide: there are highly specialized devices that display only voltage; There are devices equipped with an additional USB socket for charging mobile gadgets or a built-in thermometer.

The main advantage of such measuring instruments is their ease of installation, namely, just insert the device into the cigarette lighter and you can control the voltage of the on-board network.

No additional work (installation of a toggle switch, additional relay or fuse) is required. Disadvantage: quite often the cigarette lighter socket is initially installed in a poorly visible place.

Voltmeter with switch

Another simple and reliable way is to install a measuring device with a built-in switch. Installing such a voltmeter on a motorcycle is extremely simple:

• we fix the device in a convenient and clearly visible place (usually using a clamp on the steering wheel spoke);
• lay the wires from the device to the battery;
• connect them to the battery (red to “+”, black to “–”);
• install a 0.5÷1.0 A fuse in the cut of the red wire (if one is not included in the delivery set);
• We secure the wires with plastic clamps.

Attention! After you have turned off the engine, be sure to turn off the voltmeter using the switch. During long-term parking, the device can drain the battery quite significantly.

Connection to the ignition switch

Modern digital voltmeters designed for installation on a motorcycle have a very small current consumption (usually no more than 20 mA). Therefore, they can be connected directly to the ignition switch contacts (without the risk of burning the contacts). Installation algorithm:

• we mount the measuring device in a place convenient for viewing (for example, using double-sided tape);
• We connect the black wire to ground (under any mounting screw);
• We find the +12V switched contact on the ignition switch and connect the red wire from the voltmeter to it.

On a note! Using a multimeter, we find the contact where +12V appears after turning on the ignition. We connect the red wire of the voltmeter to it. Sometimes this method turns out to be easier than connecting to the ignition switch contacts.

Connecting a voltmeter via an additional relay

The most correct (from a technical point of view) way to connect a voltmeter for any motorcycle is to use an additional relay. For this method you will need:

• any 4 or 5-pin automotive relay (for example, 90.3747-10 costing 70÷100 rubles);
• adapter block (price 40÷60 rubles);
• wires, insulating tape, plastic clamps.

The connection diagram is simple:

• relay contact 86 is connected to the switched “+” of the ignition switch;
• contacts 30 and 85 – to the “–” battery or housing;
• pin 87 – to the minus of the measuring device (black wire);
• We connect the red wire of the voltmeter to the “+” of the battery.

Now, when the ignition is turned on, the relay will be activated and the voltmeter will be connected to the battery through closed contacts (30 and 87).

A voltmeter in a car is a rather rare feature. This probably happens because the average motorist is unlikely to often think about voltage, which cannot be said about those who like to keep everything under control... Installing a voltmeter in the car yourself will help you always be aware of the “volts”!

Which voltmeter to choose?

It is extremely difficult to find a car voltmeter, and even a decent looking one, in stores. This happens because such equipment is installed from the factory in literally single cars. If we discard the tuned instruments, then in reality you can only find voltmeters from the VAZ-2107 and UAZ.

The voltmeter from the VAZ “Seven” does not have a housing and this is a huge minus. According to the “statement”, it is attached to the dashboard and “naked” consists of unprotected windings on a small frame and an arrow made of soft metal...

The UAZ voltmeter is a full-fledged device in a sturdy case. The only real negative is the appearance. It is, as befits this car, extremely unpretentious, even military.

The design and quality of the voltmeters considered are unlikely to be suitable for beautiful tuning. Therefore, for those who not only add functionality to their car, but also take into account the interior design of the car, it is better to look for a specialized tuned device.

The principle of operation of a voltmeter in a car

A voltmeter is a device with a fairly simple internal structure, the main purpose of which is to measure the voltage in the network. The principle of operation of a voltmeter is the interaction between an electromagnetic coil and a permanent magnet or two electromagnets. The current passing through the coil deflects the voltmeter needle the more strongly, the higher the voltage value.

In modern devices, readings are converted into a digital display, which is clearly visible even at night in an unlit car interior. The accuracy of such sensors is much higher than analogue “pointer” models, and depends on the discreteness of the main component - the analog-to-digital converter. The input voltage, flowing through the wires, is converted into a digital signal, which is then converted from binary code to a numerical value and displayed on a backlit display.

Principle of operation

Electromechanical type meters were the first to be created. They operate using the magnetoelectric principle. A permanent magnet is fixedly fixed, and a steel core is installed between its poles. This structural element is installed in such a way that a constant electromagnetic field can be formed in the annular air gap.

A frame made of aluminum is installed in the gap on the axle shafts. She is able to move freely. There is also a spool of thin wire on the frame. The indicator arrow of the device is attached to the frame using springs. As soon as an electric current begins to pass through the device, an electromagnetic field appears in the winding. The frame interacts with it and deflects along with the arrow to a distance corresponding to the voltage value.

The design of the meter also contains an induction damper - an aluminum plate mounted on a frame with an arrow. In accordance with Lenz's rule, eddy currents arising in the damper interact with the magnetic field that generated them and slow down the oscillations of the device pointer. To achieve the required measurement accuracy, the device must not be exposed to gravity during operation.

To solve this problem, the moving part of the meter is equipped with a system of weights moving on rods. In addition, to ensure accurate measurements, it is necessary to reduce the friction force of the steel tips. This is achieved through the use of special wear-resistant steels. Parts made from them are polished.

Before starting the measurement, the user needs to set the indicator arrow to the zero position.

For this purpose, the design of the device includes a special adjustment screw connected to a spring. This is a classic design, but today there are devices containing magnets of different shapes. Moreover, in some designs the magnet is movable.

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Selecting a voltmeter model

Digital voltmeter circuit.

The modern market of devices for cars offers a wide selection of voltmeter models. The most popular types of devices are:

• analog “pointer” voltmeters - installed mainly on domestic cars, connecting to the dashboard instead of a clock,
• digital sensors connected to the cigarette lighter socket,
• digital voltmeters mounted in the dashboard.

The last two types of devices are most often used, as they combine a modern appearance, accurate readings and ease of installation.

The measurement results that best correspond to reality are provided by voltmeters connected directly to the dashboard. Although their installation is sometimes fraught with some difficulties, by installing them you can get constant monitoring of the battery condition, which is especially important when there are a large number of connected components. Automotive voltmeter

The cost of a digital voltmeter is quite low and ranges from 120-150 rubles if ordered through online stores. It has a standard rectangular shape, thanks to which it will harmoniously fit into the interior of any car. Backlight color – white, yellow, blue, green, red. Sometimes a problem arises with the high brightness of the screen, which acts as a distraction and makes it difficult to concentrate on the road, but this problem can be quickly solved with the help of a tint film.

To increase the accuracy of the voltmeter, it is recommended to choose those models in which 4 digits are allocated for voltage readings. This way you can take values ​​down to hundredths of a volt.

How much does a car voltmeter cost?

The cost of a voltmeter depends on the place of purchase, brand and accuracy. The cheapest devices that still have sufficient accuracy for the average driver can be purchased on eBay. Alibaba and AliExpress. There, the cost of various automobile voltmeters starts from 150 rubles with free delivery. In Russian online stores, including Yandex Market, the cost of automobile voltmeters starts from 400 rubles , not including delivery fees. In regular stores, prices are even higher and start from 500–700 rubles . Multimeters with frequency meter mode cost from 2 thousand rubles .

Installation specifics

Table of characteristics of a digital voltmeter.

If there are no problems during installation with digital voltmeters that are powered from the cigarette lighter, then models installed directly into the dashboard often force drivers to think about the order in which they are connected.

Most voltmeters on the market have two or three wires for connecting to the network, although there are models with four contacts. The wires have standard color markings:

• the red wire corresponds to “plus”,
• the black wire is connected to the negative
• The white wire is responsible for controlling the backlight intensity and turning the device on and off.

Interpretation of instrument readings

Installing a voltmeter is only the first step in gaining control over the condition of the vehicle's battery and electrical system. Complete information can be obtained only by determining the basic values ​​of the device indicators.

The standard battery voltage in passenger cars is 12 V. The on-board voltage readings will be slightly different, amounting to 13.7-14 V. If the values ​​on the voltmeter decrease relative to the specified parameters, this may indicate a breakdown of the voltage regulator or a malfunction in the generator.

A decrease in voltage may also be due to the battery being discharged. This happens especially often in winter: in the cold, discharge occurs faster, and the presence of a heater in the car adds load to the network.

Figure 2. Diagram of connecting a voltmeter to a circuit.

If the voltmeter is connected directly to the battery terminals, then by its numerical values ​​you can easily find out the battery charge level. Readings in the range of 12.6-12.9 V indicate that your battery is fully charged. As the discharge progresses, the voltage gradually drops. At a value of 12.3-12.6 V, the charge drops to 75%; at 12.1-12.3 V, the battery is approximately half discharged. With a gradual decrease in voltage to 11.8-12.1 V, the battery is considered 3/4 empty, and at 11.5-11.8 V you will no longer be able to start the car.

To obtain complete information about the state of the network, it would be a good idea to measure the voltage directly at the battery terminals, and then compare it with the readings of the on-board voltmeter. If, when you turn on the heating, high beams or other loads, the voltage differs by more than 0.4 V, this may indicate an unstabilized on-board network. In this case, it is necessary to check the serviceability of the generator and voltage relay as soon as possible.

Pinout of the dashboard of VAZ2110, 2111, 2112

1. fuel reserve warning lamp;
2. dashboard lighting lamps;
3. right repeater indicator lamp;
4. left repeater indicator lamp;
5. VAZ plug block;
6. coolant temperature sensor;
7. indicator lamp for external lighting;
8. carburetor air damper warning lamp;
9. oil pressure warning lamp;
10. handbrake indicator lamp;
11. battery charge indicator lamp;
12. VAZ tachometer;
13. indicator light “CHECK ENGINE”;
14. speedometer dashboard;
15. brake fluid level warning lamp;
16. hazard warning lamp;
17. high beam indicator lamp;
18. fuel level indicator.