22 Years' Battery Customization
Aug 16, 2021 Pageview：1410
The car battery reserve capacity is the number of minutes for which it can easily run at 25 Ampere Hour. If you have no idea about this term, let’s find out every detail in the following.
Car Battery Reserve Capacity to Amp Hours
The first criteria used when comparing and selecting batteries is generally their capacity and power. Conventionally, the capacity is given in Ah, (Ampere hours). Until now the unit of capacity of all batteries has been expressed in this unit.
The capacity of a normal starter battery is 56 Ah.
In practice, this is not significant, since it does not mean more than the possibility of obtaining, for a certain time, a current from a battery, and being able, for example, to keep a lamp illuminated during that time. The old C20 test is the basic test of the capacity of a starter battery. This test determined that the battery would have to be able to keep the position lights of a car on for 20 hours.
Amp-hours do not tell us how efficient a battery can be at starting a motor.
Car Battery Reserve Capacity Definition:
The most important function of a starter battery is of course to start a vehicle. The worst conditions under which a battery can be expected to deliver current are low temperatures. Therefore, it seems logical that a good test is to calculate the amount of current, measured in Amps, that a battery can give in cold conditions.
The unit of measure used is CCA (Cold Cranking Amps, or 'cold-cranking capacity).
This is a better way of measuring the capacity of a starter battery than the old Ampere-hour measurement.
CCA measures according to the American SAE standard - how much current can be delivered during 30 seconds at -180 C with a final voltage of greater than or equal to 7.2 Volt.
Reserve Capacity – Another Important Measure of a Battery:
Reserve capacity is an important measurement in a car battery. It is measured according to the SAE standard, approved by the International Battery Council (BCI).
The Reserve Capacity of a battery is measured in minutes. It is the number of minutes that a fully charged battery can deliver 25 amps. The test consists of a discharge of the battery at 25 A as long as the voltage remains above 10.5 Volts.
This test simulates the time that the battery could power the essential accessories of the vehicle, driving at night, and in the event of a generator or alternator failure.
Reserve capacity is also a measure of the total capacity of a battery.
Car Battery Reserve Capacity Minutes
Batteries can also be compared according to different discharge variables, depending on how they are to be used. The typical test is the SAE test called the ‘20-hour test’. This test shows the current that can be drawn from a battery in 20 hours without the voltage dropping 1.7 Volt per cell.
We can illustrate this by looking at how the surface area is related to power and energy. If we fill a bucket with an amount of gasoline and set it on fire, we will see that we get a flame that burns for several minutes, depending on the amount of gasoline used. If we pour the same amount of gasoline on a flat surface, it will burn in a few seconds.
And finally, if we spray the same amount of gasoline into a carburetor, it will burn in a fraction of a second. The same amount of energy is released in each example. In this succession of examples, the exposed surface area is increasing and the burning time that is achieved is becoming shorter.
The Effect of Resistance on Starting Capacity:
Do you know what CC, CSC, and CR mean in your car battery?
These three terms are essential when choosing your car battery, know their meanings:
1. Cranking Capacity (CC): Amount of amps the battery uses to drive the starter under 0 ° C conditions.
2. Cold Start Capability (CSC): Amount of amps the battery uses to drive the starter in -18 ° C conditions.
3. Reserve Capacity: (RC): Determines how many minutes the battery will continue to supply a constant electrical current, at full load and temperature.
In theory, conventional starter batteries should give more power than they do. The problem is in the internal resistance caused by the design of the battery. This resistance prevents electrons from circulating through the circuit. One cause of resistance in conventional batteries is the distance between plates. The chemical reaction will be faster if the plates are close to each other. Another cause of resistance is the limited surface area of ??active material. The larger the surface area of ??pure active material, the lower the resistance.
In practice, this means that, mainly because of its internal resistance, a conventional battery produces or stores a greater amount of energy than it can quickly release. To understand this better, we can compare the conventional battery to a bottle and the Optima battery to a glass.
The neck of the bottle causes resistance, it does not let out all the energy produced in the battery. On the other hand, in the case of the glass, that is to say, of the Optima, the resistance is negligible. Power can flow from the battery without any resistance. The opening of the battery is large compared to the neck of the bottle.
To get the same starting power from a conventional battery as from an Optima, the conventional battery would have to be two or three times larger. It could be said that it is the internal resistance of a battery that determines its size.
Using the old method of measuring capacity in Ampere hours, an Optima battery and a conventional car battery have the same result of 56 Ah. However, this measurement is not representative as it only shows how long the battery can retain a certain voltage while providing a slow current.
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