1. Introduction to power battery characteristics

Pure electric vehicles have no engine and fuel tank. The driving motor replaces the engine, and the power battery replaces the fuel tank. The power battery system is the only power source of the pure electric vehicle, which provides power for vehicle driving and other electrical appliances. The power battery is the core key component of the pure electric vehicle, which is closely related to the safety, power and economy of the vehicle. Electric vehicle charging pile

Mainstream power batteries include: ternary lithium battery, lithium iron phosphate battery, nickel hydrogen battery, fuel battery and graphene battery.

2 Composition and function of power battery

Single cell: the smallest unit that directly converts chemical energy into electrical energy, including positive pole, negative pole, electrolyte, shell, etc.

Battery module: It is composed of multiple single batteries in series, parallel or series parallel hybrid mode, and is used as a combination for power supply.

Power battery pack: the general name of all electrically connected batteries used to provide energy for the power circuit.

Function of power battery pack:

(1) Provide electric energy

(2) Calculation of electric quantity (SOC)

(3) Temperature and voltage detection

(4) Battery consistency and leakage detection, abnormal condition alarm

(5) Charge and discharge control, pre charge control

(6) System self inspection

3 Power battery parameters

1. Charging termination voltage

The charging termination voltage (upper limit protection voltage) is the maximum charging voltage required for charging of single battery/battery module/battery pack, in volts (V).

2. Discharge termination voltage

The discharge termination voltage (lower limit protection voltage) is the minimum discharge voltage required when the single battery/battery module/battery pack discharges, in volts (V).

3. SOC

State of Charge is the current capacity of the battery, expressed as the percentage of the current capacity to the total capacity of the battery at room temperature.

Factors affecting SOC: discharge current, battery temperature, battery capacity attenuation, battery self discharge rate, battery consistency, etc.

4. Nominal capacity versus actual capacity

The nominal capacity is based on the results of the test published by the state, New energy vehicle charging pile It is the total battery data measured after the battery is fully charged and discharged under the constant temperature environment.

SOC displayed by the vehicle is 0% ≠ all batteries are discharged

The SOC displayed on the vehicle is 100% ≠ the battery is fully charged

5. Energy density

Energy density refers to the amount of energy stored in a certain unit of space or mass. The energy density of the battery is the electric energy released by the average unit volume or mass of the battery. The energy density of battery is generally divided into two dimensions: mass energy density and volume energy density.

Battery mass energy density=battery capacity × discharge platform/mass, basic unit: Wh/kg (watt hour/kg).

Battery volume energy density=battery capacity × discharge platform/volume, basic unit: Wh/L.

6. Power density

The power density is used to describe the capacity of the battery to release energy instantly, and the unit is W/kg.

The power battery with high power density is like a runner in the 100 meter race. It can charge and discharge at a fast speed and provide high instantaneous current to ensure the acceleration performance of the car.

4 How to maintain the power battery?

(1) During the normal use of the vehicle, the battery management system will correct the battery performance to give full play to the best performance.

(2) When the vehicle is left unused for a long time, pay attention to:

① It is strictly prohibited to be in the state of power loss when placing, and the SOC should be between 30% and 70%.

② Disconnect the negative pole of the low-voltage battery.

③ Full discharge (DM to 5%) and full charge shall be conducted every three months.

(3) When the ambient temperature is s-20 ° C, the vehicle shall be stored in the warm warehouse.

In addition, it is also important to avoid stepping on and accelerating sharply when starting, carrying people, and going uphill, New energy vehicle maintenance Instantaneous high current discharge will affect battery life. Grasp the charging time and frequency. Overcharging, overdischarging and undercharging will shorten the battery life.

5 How to use the battery in winter?

(1) Charge in time to avoid grounding due to low power.

(2) Try to ensure that the vehicle is charged every day after use.

(3) Low power charging equipment shall be used for charging at low temperature in winter.

Low current charging can deeply charge the battery, which is conducive to improving the battery charging capacity.

(4) Properly store the vehicle to keep the battery active. When the new energy vehicle is not used for more than half a month in winter, the power electric