When choosing a new battery, it is important to choose the product that will fit the vehicle. The most important battery parameters are capacity, polarity and size, but if the battery has an insufficient level of inrush current, then the machine may not start at all. About what is the starting current, and how to choose the right battery for this parameter will be described in detail below.
Content
- What is inrush current and what does it depend on
- What affects the starting current of the battery
- What should be the starting current for starting the engine
- How can I check the starting current of the battery
- Is it possible to take a battery with a large starting current
- Is it possible to take a battery with a lower starting current
- How to choose inrush current according to vehicle parameters
What is inrush current and what does it depend on
The inrush current is also called the cold scroll current, which indicates the main value of this parameter for the machine. When the engine is not warm, the oil in it is in a more viscous state, so at the time of starting the starter consumes a large amount of electricity.
Given the extremely low resistance of the motor winding to perform rotor rotation, you will need to supply a lot of electricity from the battery and the higher the cold current, the easier it will be to start the car.
The power of the electric current is calculated by the formula: P = UI.
In this expression, P is the power; U is the voltage; I is the current strength. The voltage of a working battery is approximately 12 Volts, therefore, the greater the current value, the higher power the starter motor can develop. You should also take into account the fact that at the time of starting the electric motor this parameter is always higher than when its speed increases significantly, so the car starter battery must have a significant margin for this indicator.
The starting current of the battery depends on the number of lead plates. That is, the larger the area of both negative and positive electrodes, the higher will be the cold scroll current.
What affects the starting current of the battery
As was proved above, this parameter affects the power of the electric motor of the starter. Increasing the power allows the rotor to rotate at high speeds, so the engine crankshaft, at the time of starting the engine, also spins much faster. The faster the pistons rotate, the greater the number of compression strokes per unit time, so the diesel engine starts much faster. In a gasoline engine, an increase in the crankshaft speed also leads to a reduction in the start time.
If the battery possesses the necessary characteristics of the starting current, then even in severe frosts the car can be started without resorting to additional measures to warm the engine. If the engine starts and does not happen as fast as in the summer, then a more powerful battery will allow you to rotate the pistons for a longer time without a significant reduction in speed, which will lead to the heating of the rubbing parts and easier ignition of the combustible mixture.
What should be the starting current for starting the engine
The inrush current for starting a certain brand of engine must be calculated at the factory of the power unit. The performance of this parameter increases with increasing capacity, so if you know which battery was on the car, then you can easily pick up a new battery by capacity. In this case, the electrical parameters will fully correspond to the make and type of car.
If it is necessary to install the battery on a vehicle in which there was no battery, then products with the following minimum indicators of the cold scroll current are selected:
- For passenger cars - 350 A.
- For trucks - 800 A.
As for the capacity, batteries for cars from 45 A / h should be selected for cars, and for trucks this parameter should not be lower than 110 A / h. The listed parameters are approximate and for a more accurate selection of the battery, you should know the power of the engine, to start which a battery is purchased.
How can I check the starting current of the battery
By ear, you can make only comparative tests of batteries in terms of current cold scroll. If the engine rotates at a higher frequency when starting and the car starts up faster, then this indicator is noticeably higher for this battery model.
Precisely measure the inrush current using a special device. As a rule, in order to check the battery’s performance during the sale, diagnostics are performed using a load plug. Such a device consists of a low resistance load and an integrated measuring device that displays voltage. Thus, it is possible to evaluate the general condition of the battery, but it is practically impossible to accurately determine the value of the discharge current.
It is possible to determine the value of the cold scroll current of the battery with high accuracy only by a professional tester. Such devices cost several tens of thousands of rubles, so this method is completely unsuitable for a single use.
Is it possible to take a battery with a large starting current
Contrary to popular belief, the installation of a more powerful battery will lead to the failure of automotive electronics, including the starter, we should recall the school physics course, which explains the basic laws of electricity consumption. Regardless of the battery power, the devices will consume only the necessary amount of electricity, and the starter can only fail if the limit for a single start of this element of the car’s electrical system is significantly exceeded.
Difficulties with installing a more powerful battery can arise only due to insufficient space in the engine compartment. The greater the battery power, the larger its dimensions. Particularly, the length of the product increases with increasing capacity and power, so you can only install a product that significantly exceeds the standard battery in power for this model of the machine only after making changes to the design of the battery mounting location.
Is it possible to take a battery with a lower starting current
Despite the fact that a battery with a lower starting current can almost always be installed in a regular place, you should not buy such a battery. If the battery will give less power than is necessary for the normal operation of the starter, the rotation of the rotor of the electric motor will occur with a much smaller frequency.
Accordingly, the rotation of the crankshaft will also not be carried out fast enough, which may cause the lack of starting the internal combustion engine. If this indicator is at a very low value, then the rotation of the electric motor can practically stop, which will damage the brushes and the collector of the starter.
How to choose inrush current according to vehicle parameters
The starting current of the battery is selected based on the following parameters:
- Engine's type.
- The presence of additional electrical equipment.
- Operating conditions.
The more powerful the engine and the greater the number of pistons the power unit has, the greater the amperage required to start it. Powerful audio amplifiers, HVAC equipment and additional lighting will also require more electricity.
If the car is operated in harsh climatic conditions, for example, in the Arctic, then a more powerful battery should be installed on the car, which will allow the engine to start even at very low air temperatures.
