Every car owner wonders whichNeed a device to measure battery capacity. Measurement of this value is often carried out during the passage of a planned maintenance, but it will be useful to learn how to determine it yourself.
Device for measuring battery capacity
Battery capacity is a parameter thatdetermines the amount of energy given off by the battery at a certain voltage in one hour. It is measured in A / h (Ampere per hour), and depends on the density of the electrolyte, which is determined by a special device - a hydrometer. When buying a new battery, all the technical parameters of the manufacturer indicates on the case. But this value can be determined and most. For this there are special devices and methods.
The easiest way is to take a specialtester, for example "Pendant". This is a modern device for measuring the capacity of a car battery, as well as its voltage. In this case, you will spend the minimum amount of time and get a reliable result. To check it is necessary to connect the device to the battery terminals and within a few seconds it will determine not only the capacity, but also the battery voltage and the state of the plates. However, there are other methods for determining the capacity of the battery.
The first method (classic)
For example, a multimeter can be used asa device for measuring the capacity of a car battery, but with it you will not get accurate readings. A prerequisite for this method (it is called the test discharge method) is the full charge of the battery. First you need to connect a powerful consumer to the battery (a conventional 60W light bulb is quite suitable).
After it is necessary to assemble a chain, which consists ofmultimeter, battery, consumer, and apply the load. If the light bulb does not change its brightness for 2 minutes (otherwise the battery cannot be restored), we take the readings of the device at certain time intervals. As soon as the indicator drops below the standard battery voltage (under load it is 12V), its discharge will begin. Now, knowing the amount of time it took to completely empty the energy reserve and the load current of the consumer, it is necessary to multiply these values. The product of these quantities is the actual capacity of the battery. If the values obtained differ from the passport data in a lower direction, the battery must be replaced. This method makes it possible to determine the capacity of any battery. The disadvantage of this method is time consuming.
The second method
You can also use the method in whichThe battery is discharged through a resistor using a special circuit. Using the stopwatch we determine the time spent on the discharge. Since energy will be lost at a voltage within 1 Volt, we can easily determine the strength of the current using the formula I = UR, where I is the current, U is the voltage, R is the resistance. At the same time, it is necessary to avoid complete discharge of the battery, using, for example, a special relay.
How to make the device yourself
In the absence of the possibility of acquiring a finished device, you can always assemble a device for measuring battery capacity with your own hands.
To determine the degree of charge and battery capacityYou can use the load plug. There are many models of ready-made forks, but you can assemble it yourself. Next is considered one of the options.
This model uses an extended scale,thanks to what high accuracy of measurements is achieved. There is a built-in load resistance. The scale is divided into two ranges (0-10 V and 10-15 V), which gives an additional reduction in measurement error. The device also has a 3-volt scale and another output of the measuring device, giving the opportunity to test individual cans of batteries. The 15V scale is achieved by reducing the voltage on the diode and the zener diode. The current value of the device increases if the voltage exceeds the opening level of the Zener diode. When energizing with an incorrect polarity, the diode performs the protective function.
In the diagram:R1- transmits the required current to the zener diode; R2 and R3 - resistors selected for M3240 microammeter; R4 - defines the width of the narrow range of the scale; R5 - load resistance, included with the SB1 switch.
The load current is determined by Ohm’s law. The load resistance is taken into account.
AA battery capacity meter
The capacity of AA batteries is measured in mA / h(milliamps per hour). To measure such batteries, you can use special chargers that determine the current, voltage and capacity of the battery. An example of such a device is the AccuPower IQ3 battery metering device, which has a power supply with a voltage range of 100 to 240 volts. To measure the need to insert batteries into the device, and the display will show all the necessary parameters.
Determination of capacity using a charger
Также емкость можно определить и с помощью normal charger. Having determined the magnitude of the charge current (it is indicated in the characteristics of the device), it is necessary to fully charge the battery and record the time spent on this. After multiplying these two values, we obtain an approximate capacity.
More accurate readings can be obtainedusing another method for which you need a fully charged battery, a stopwatch, a multimeter and a consumer (you can use, for example, a flashlight). We connect the consumer to the battery, and with the help of a multimeter we determine the current consumption (the smaller it is, the more reliable the results). We notice the time during which the lamp shines, and multiply the result by the current consumption.
