The battery is a reusable current source that serves to autonomously power various devices, and in this case, a car. Therefore, over time, the capacity of the tank may decrease, as a result, the time of its operation without additional charge decreases.
Battery Metrics
Nominal capacity - this unit most often serves to determine the electric charge of power sources. The nominal capacity of the car battery is expressed in Ah, that is, in ampere hours, or Ah (Ah - ampere - hour in the English abbreviation).
The voltage is measured in volts, V. The batteries used in cars most often have a standard rating of 12 V. This is a characteristic indicated in the technical data sheet. And the voltage value is often indicated after the brand, for example, BOSCH 63 Ah, where 63 is the capacity of the car battery, Ah.
Checking with a tester
So, for starters, a car enthusiast asks how to determine the residual capacity of a car battery.
Special testers are used to determine how much capacity is available and to understand how efficient it is. These are indispensable devices for checking all types of batteries, their functionality is huge. The tester is not difficult to operate at all and in most cases it has only one button, with which the indicators of various parameters are determined, for example, both the volume of the capacitance and the current strength. The results obtained will not necessarily accurately reflect the state of the battery, but if desired, using simple formulas, you can summarize the final calculation of the capacity of the car battery.
Multimeter application
A multimeter (or avometer, from the word ampervoltmeter) is also a combined instrument used to measure the performance of electrical appliances.
It also has several modes of operation, it is not difficult to operate.
You can measure and find out what the capacity of the car battery is in several ways.
Load testing
An ordinary light bulb will act as a load. If the level of its brightness decreases during measurements, then testing stops immediately, as this will indicate poor battery performance - there is not enough charge or the device’s circuitry is broken.
To calculate the required load for the capacity of the car battery, the first thing to consider is the number of amperes. If the nominal capacity is, for example, 7 Ah (Ah), then the corresponding load will be 3.5 volts. If you do not have the right light at hand, an ordinary car headlight is perfect.
Measurement process
How to determine the capacity of a car battery, every motorist should know!
To determine the battery capacity measurements, the following actions are carried out in the exact order:
- First you need to disconnect the battery from the generator.
- Next, bring the load in the form of a light bulb and let the battery run for just a couple of minutes. Then turn it off.
- Then a multimeter is supplied to the battery and measured within 20 seconds.
Indicators record.
If the voltage is 12.5 volts, then the battery is in good condition. But if the indicators are equal to 11.5 or even lower, then it is necessary to replace the battery.
Control discharge method
In order to measure the capacity of a car battery in this way, you need to know the current strength of the discharge of a particular power source. To do this, you can see the technical documentation attached to it. The capacity of the discharge current of the capacitance will be equal to the required load level, which will apply to the battery.
In such a measurement of the volume of the capacitance, the multimeter should remain connected to the battery for such a long time until the current strength drops to 60, and preferably 50%. As a result, a value will be obtained that must be compared with the value in the technical data sheet of the battery. Most likely, they will not coincide, since each charge / discharge of the battery gradually reduces its working capacity, but the numbers should not vary much! If the discrepancy is large, there is only one conclusion - battery replacement.
Measurements of other indicators
A modern multimeter is a device with great functionality. It is suitable for measuring other parameters of a power source.
Voltage measurement
If the battery is alkaline-acid or lithium-ion by type, then it is possible to measure the voltage of the battery by putting it into voltmeter mode. Depending on the load level of the measured device, set up a multimeter by setting the corresponding indicator. After that, a black wire is brought to the negative terminal of the battery, and red, respectively, to the positive. Within the next 2 seconds, the voltage indicator will be displayed on the multimeter screen.
If the battery is serviceable, then the value of the indicator will be 12-12.5 Volts. This will indicate that the condition of the power source is normal.
Internal resistance test
Here again, you need a 12 V bulb and, of course, a multimeter.
The internal resistance of the battery is also an important indicator of performance.
To take a measurement, the car enthusiast or the master acts in the following order:
- A light bulb is connected to the battery. The battery is by no means charged!
- After a couple of seconds, a multimeter is connected to the battery terminals and the first voltage measurement is done.
- The lamp turns off.
- And a second voltage measurement is performed.
If there is a difference in the numbers received, but it is not higher than 0.05 V, then the battery is considered serviceable. If the difference is higher, then either a replacement or inspection and additional tests are required. Internal resistance must not exceed the norm!
Leakage current
If the above measurements are not so difficult to understand and remember the actions, then we need to proceed to the question of how to check the capacity of the car battery for current leakage. This is an indicator on which the volume of the battery capacity itself directly depends, and therefore the term of its “life”.
The self-discharge level allowed for the battery at rest is specified in its technical documentation. However, you should know that alkaline types of batteries have the highest level!
Any leakage means an open or poor sealing in the battery supply circuit. And if the leakage level was determined during measurements much higher than the technically acceptable level, then the battery will be discharged even faster. But not only battery discharge can be a problem, because poor insulation of individual sections of the power circuit can lead to a short circuit or fire!
To test the level of battery current leakage, the multimeter is put into the appropriate mode, and the voltage indicator is set to 10 Amps. They connect the multimeter in this way: the red wire is connected to the positive terminal, and the black wire is disconnected at all.
The leakage rate is defined as follows: if nothing is displayed on the device’s monitor, then the car battery’s capacity test was successful, there is no leakage! If there is any indication, then it is urgent to check the entire on-board system.
Power Supply Recovery
After carrying out all the necessary measurements, the next logical step is to learn how to restore the “size” of the battery capacity. Indeed, in any case, especially during the long operation of the vehicle, the battery loses part of its capacity.
How to restore the capacity of a car battery?
Preparation for restoration begins with inspection and surface cleaning of the battery. It is necessary to remove all possible smudges of internal composition, dirt and oxidation from the terminals. Before flushing the tank itself, contaminated electrolyte is drained. Be sure to check the lead plates for the presence of integrity, because otherwise the recovery procedure simply does not give anything.
Next, carry out a control cycle for a full discharge and further charge of the battery. It is better to carry it out at least 4 times.
To control this cycle, you can use:
- hydrometer - to determine the density of the internal composition of the battery;
- light bulb - to create the desired load;
- voltmeter or multimeter.
Directly between the discharge cycle and the further charge of the car battery capacity in mAh, a break of about 12-14 hours is set. The duration of the charge should be at least 8 hours. The technical documentation indicates the exact parameters of the required current strength, charge time, they must be taken into account in each case.
The rest period between cycles is needed so that a single potential is established from above, on the surface of lead plates.
For each complete cycle of the discharge - charge, the density of the electrolyte composition will increase. If it becomes very high, then distilled water can be used to dilute it.
After distilled water has been drained and all containers are thoroughly washed, sodium solution is poured into the battery. Its filling is also done in several approaches, 2-3 times.
Rules of Manipulation
When working with any electrical appliance, everyone should know that power surges caused by forced disconnection from the power supply will adversely affect the device itself. Therefore, all actions should occur whenever possible with the engine turned off. If there was a need to replace the battery with the engine running, then to minimize power surges, you must turn on all electrical appliances in the car (heated rear window, headlights, radio). And connecting / disconnecting each terminal as quickly as possible, without repeated touches. Thus, unwanted power surges will be minimized.
If there is a need to charge the battery from other equipment, then the devices should be connected with careful accuracy. Otherwise, it may also cause a malfunction of the devices.
Interesting Facts
The concept of "best battery" simply does not exist. Different types serve different purposes. For example, calcium batteries have a low leakage current, but at the same time they hardly tolerate deep discharges, especially in winter. At the same time, for standard “serviced” batteries, for example, lead-acid, with a car battery capacity of 18Ah, this discharge will not be critical, but it will be necessary to constantly measure and rinse and top up with distilled water.
If the temperature is low, then the ability of the battery to "charge" is sharply reduced. Therefore, short trips in the cold can lead to a faster discharge. Even if the battery is new! And this will lead to the inability to start the motor!
In winter, a heated design that will accelerate the temperature increase in the internal composition of the battery will be a good help for the battery. After all, it has a certain viscosity, so its temperature decreases or rises after the ambient temperature, with a delay. And in order to help the battery more efficiently receive a charge from the generator, it is necessary to provide an additional source of warm air. And this, in turn, will help slow down the discharge of the battery during rest. Also, the device can be taken home and, after warming to room temperature, put on charge.
The more regularly the performance indicators of the power source and the state of the “size” of its capacity are checked, the more timely it is possible to notice an increase in current leakage, and, therefore, to carry out the restoration. The smaller the deviations, the easier it is to carry out this procedure and the more likely it is to return the lost volume. After all, battery operation inevitably leads to the destruction of lead plates, the formation of electrolyte smudges, and all this contributes to its slow failure.