The difference between car lithium 12V battery capacity and battery capacity

The difference between lithium 12v 42ah Lifepo4 Battery  capacity and battery capacity for vehicles. In the context of the era of energy conservation and environmental protection, electric vehicles have become an inevitable trend in the development of the automotive industry. Lithium batteries and accumulators for vehicles are the two major use of electric vehicles. What is the difference in capacity?

Car lithium 12v battery capacity

The amount of power that a 12v 42ah Lifepo4 Battery  can give under certain discharge conditions is called the capacity of the lithium battery, which is represented by the symbol C. The commonly used unit is ampere hour, abbreviated as ampere hour (Ah) or milliampere hour (mAh).

1. The capacity of LiFePo4 can be divided into theoretical capacity, rated capacity, and actual capacity.

2. Theoretical capacity is the highest theoretical value obtained by calculating the mass of the active material according to Faraday’s law. In order to compare different series of lithium batteries, the concept of specific capacity is commonly used, that is, the theoretical power that a unit volume or unit mass lithium battery can give. The unit is Ah/kg (mAh/g) or Ah/L (mAh/cm3).

3. The actual capacity refers to the amount of power that the lithium battery can output under certain conditions. It is equal to the product of discharge current and discharge time, the unit is Ah, and its value is less than the theoretical capacity.

4. The rated capacity is also called the guaranteed capacity, which is the minimum capacity that the lithium battery should discharge under certain discharge conditions according to the standards promulgated by the state or relevant departments.

Battery capacity

Storage lithium phosphate refers to all chemical energy batteries that can be recharged and used repeatedly after the power has been used to a certain extent. Also known as a rechargeable battery, the reason why it can be charged is that its chemical action can be reversed when it is connected to an external power source. There are many kinds of chemicals that make batteries, and their designs are also different; therefore, their voltage, capacity, appearance size, and weight are also different.

Capacity refers to the amount of electricity that the lithium phosphate can output to the outside within the allowable discharge range when the lithium phosphate is fully charged. The unit is ampere hour. The 12v battery capacity is used to indicate the ability of the battery to supply power to the outside. When the battery is discharged at a constant current value, its capacity Q is equal to the product F of the discharge current I and the discharge time t

The capacity of the lithium phosphate is related to factors such as the size of the discharge current and the temperature of the electrolyte. In order to accurately indicate the accurate capacity of the battery, the discharge conditions of the battery must be specified. Under certain discharge conditions, the capacity of the battery is divided into rated capacity and starting capacity.

1. Rated capacity

The rated capacity refers to the current discharged at a rate of 20h (equivalent to 1/20 of the rated capacity) of a fully charged battery when the average temperature of the electrolyte is 25℃, and the output is continuously discharged to a single cell voltage drop of 1.75V Power.

For example, 3-Q-90 type battery, when the average temperature of electrolyte is 25℃, after 20h continuous discharge with 4.5A discharge current, the single cell voltage drop is 1.75V, its rated capacity Q=4.5×20= 90(A·h)

2. Starting capacity

Starting capacity indicates the power supply capacity of the battery when connected to the starter. There are two starting capacities at normal temperature and low temperature.

Normal temperature starting capacity: when the temperature of the electrolyte is 25℃, the current discharged at the rate of 5min (current of 3 times the rated capacity) is continuously discharged to the specified end voltage (4.5V for 6V battery, 9V for 12V battery) The discharge duration of the output power should be more than 5min. For example, when the 3-Q-90 battery is discharged at 270A for 5 minutes at 25°C, the terminal voltage of the battery drops to 4.5V, and its starting capacity is 270×5/60=22.5A.h.

Low-temperature starting capacity: the low-temperature starting capacity, that is, when the electrolyte temperature is -18℃, the electricity discharged when the current of 3 times the rated capacity is continuously discharged to the specified end voltage (12v battery is 6V, 6V battery is 3V), and The discharge duration should be more than 2.5min.

Summary: The difference between lithium lifepo4 100ah capacity and battery capacity: lead-acid battery capacity is about 20 amps; lithium battery capacity is 8-10 amps. Comparing the difference between the capacity of the lithium battery for vehicles and the capacity of the battery is related to factors such as the discharge current, the temperature of the electrolyte, the density of the electrolyte, and the structure of the electrode plate. Different models have different capacities. However, the unit of measurement for the capacity of lithium batteries and batteries for vehicles is the same, and there are two types: AH number and WH number.Sometimes, lithium car battery can also play an important role.

The difference between 12V lithium battery and battery for vehicles

2-lithium batteries for car

1. The principle is different: the battery is a kind of battery, and its function is to store the limited electric energy and use it in a suitable place. Its working principle is to convert chemical energy into electrical energy. Lithium batteries are a type of batteries that use lithium metal or lithium alloy as the negative electrode material and use a non-aqueous electrolyte solution.

2. The price is different: the price of the battery is relatively cheap. Compared with the battery, the price of the lithium battery is higher.

3. Different safety performance: Compared with the battery, the safety performance of the lithium battery for the car is different, and the safety performance of the lithium battery is better.

4. The use time is different: compared with the storage battery, the use time of the lithium battery is relatively longer.

5. Different chemical properties: The chemical properties of lithium metal are very active, which makes the processing, storage and use of lithium metal very demanding on the environment. Regional restrictions.

6. The temperature tolerance is different: the common operating temperature of lithium battery is -20-60 degrees Celsius, but generally below 0 degrees Celsius, the performance of the lithium battery will decrease, and the discharge capacity will be reduced accordingly, so the performance of the lithium battery is fully operating temperature , The common temperature is 0~40℃. The operating temperature of the battery is generally required to be between 20°C and 25°C. When it is lower than 15°C, its discharge capacity decreases.

7. Different cycle life: The cycle number of lithium battery is generally about 2000-3000 times, while the cycle number of battery is about 300-500 times. The cycle life of lithium battery is about five or six times that of battery.Sometimes, the lithium battery price is also a very important factor.


The above is the difference between the capacity of lithium batteries for vehicles and the capacity of batteries. The characteristics of lithium batteries for vehicles will be significantly better than those of lead-acid batteries when used.

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