Is the alternator broken? This does not mean that the car will not be able to drive. The only question is the distance that a car can drive on only one battery. How many kilometers you can drive on a car battery? The answer depends on many factors: operating conditions and availability of additional energy consumers.
Devices electrical energy consumption
The electric battery, being a source of current, is designed for independent operation. The alternator is not activated immediately after the engine is started. Engine and electrical power equipment can be launched only from the battery.
The duration of use without additional charge depends on external circumstances and the battery condition. The first can be attributed to weather phenomena, the number of electrical devices and the current consumed by them. The current battery level will affect the amount of energy consumed. The same car with the devices on or off, will travel a different distance. Energy consumption figures are completely different, it is necessary to focus on the battery "freshness".
Energy consumption A new battery has the minimum consumption value, and battery with expired lifetime has the maximum consumption value.
Consuming devices | Current |
Klaxon | 1.5 – 3 Amps |
Ventilating blower | 3 – 6 Ampere |
Cruise control | 0.5 – 1 Amps |
Parking lights | 1 – 2 Amps |
Headlight and driving light | 7 – 15 Amps |
Fog light | 5 – 15 Amps |
Seat heater | 7 – 14 Amps |
Glass heating | 4.5 – 9 Amps |
Heater | 14 – 30 Amps |
Stereo | 0.5 – 2 Amperes |
Screen-wipers | 2 – 5 Amperes |
Window regulators | 5.5 – 11 Amperes |
How many kilometers can you drive without a alternator?
To calculate the distance that a car can handle, you need to know its design and basic parameters. The main indicator you should take into account during the calculation is capacity, it indicates the permissible load and corresponds to the displacement of the motor. This number is always indicated on the battery label.
A light motor vehicle car has the capacity of 55-75 A*h, the truck has a higher level. Mark on label +25 °C. By this number, you can determine the current at which the battery is completely discharged within 20 hours.
The number specified by the manufacturer is nominal; it ranges from 80 to 110% of it. Let's look at an example. Capacity is 55 A*h, the battery will be discharged in 20 h. 55/20=2.75 Amps. When making a calculation, it is necessary to take into account the value of battery energy consumption. There is a constant load that cannot be avoided. While it is possible to turn off the lights, seat heating, stereo. You also need to take into account the engine speed. To obtain the correct result, it is necessary to summarize the electricity consumption by all consuming devices.
How to calculate battery life
As an example, we take a car with an injection engine with a capacity of 60 A*h, with operating headlights, a fan is turned on, and the season is summer. Total consumption is approximately 15 Amps. Constant consumption-8 Amps. The figures appeared taking into account the injection system, which is – 4 Amps, if the carburetor system is taken into account – the figure will decrease to 2.5 Amps. The total current - 23 Amps. Operating time is calculated according to the following formula: 60/23 = 2.6 hours.
At a speed of 90 km/h, the car will be able to drive 234 km on one battery. Attention! This result is purely theoretical. It is necessary to take into account that the loss of electric energy will grow sharply during movement. These counts are close for a battery in perfect condition that is fully charged. It should be clear that in the winter season the rates will be lower.
What to do when the question arose: "To drive on one battery or not?"
In an emergency, you can count on the fact that the car will drive a short distance on a single battery. But it is better not to risk and, if possible, to assess the road. Do not think that you can overcome the maximum distance without problems, so find out the location of the nearest service station. It is better to be safe and think how you will get out of the situation if you are left alone on an empty road away from people.
Starting calculations, consider the incomplete charge of the battery, frost. You can measure the battery voltage with a voltmeter. Disconnect the battery. Figures from 12.2 V and less indicate that the charge is less than 50%. The electrolyte density is from 1.26 - 1.29 g/cm3. Here a lower figure indicates a greater degree of discharge.
For greater confidence, you can take a spare battery or recharge the one that is. Of course, this option is not for everyone.
What can be done if the alternator fails on the road?
It is possible to prepare for such failure, we will tell about it in more detail below. Now we will consider the situation when the failure occurred on the way. If you're lucky, you can drive only on one battery to the nearest service station and to solve the problem there. For now, reduce all power inputs as much as possible.
Do the following:
Do not turn on the radio, tape recorder;
Turn on the dimensions or the emergency lights instead of headlights;
Go to accelerate slowly to reduce the engine speed;
Get down from the elevations by coasting;
Do not turn off the engine, so as not to waste energy then to start it.
It is important to know! If you managed to start the car again after it stalled by “lighting up” from another car, after such a start the battery will not be able to work for a long time.
It is important to carry out diagnostics of all vehicle systems in time so that such unforeseen situations do not arise. You can check the operation of the alternator on the stand. Diagnosis will show in what condition it is that will save you from unnecessary experiences on the road.
The MSG MS002 COM test bench for diagnostics of alternators and starters is used to test 12 and 24 V vehicle alternators. The use of the bench in car service conditions will help to test the operation of starters and alternators up to 200 Amps, which means any cars and automotive trucks. Stand MS004 COM checks starters and alternators up to 100 Amps. Benches have different dimensions. MS004 COM can be placed on the desktop of the auto service technician.
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