1. Impact of charging piles
In simple terms, the greater the output power of the charging piles, the shorter the charging time, but at present, the charging piles are divided into AC charging piles and DC charging piles Charging piles, we can explain them separately.
In terms of AC piles, most of the domestic slow-speed charging piles or charging boxes use 220v AC charging, the output current is 16A or 32A, and the theoretical power can reach 3.3kw or 6.6kw, respectively. With a power loss of 10%, the AC charging speed is still very slow. For example, for an electric vehicle with a general battery power of about 20kwh, it takes 6-8 hours to fully charge the current mainstream 3.3kw AC charging method. For Tesla’s 220v HPWC (High Power Wall Adapter), the output current can reach 50A and the output power is 11kw. We still don’t have to think about it. This is specially designed for MODEL S, and the Tesla and the national standard interface are also not common. In line with national conditions, just take a look.
For DC piles, different from the 220v voltage connection of AC charging piles, the voltage connected to DC piles is 380v, and the power generally reaches more than 10kw. For example, for electric passenger cars on the market, the State Grid Most of the DC piles built are 37.5kw, and those built by Putian are also over 10kw and 15kw. For an electric vehicle with a general battery power of about 20kwh, it can be fully charged with a 10kw DC pile for 2-3 hours.
It can be seen from this that the charging speed of AC and DC can be judged only from the output power. It is said that some early electric vehicle models are only equipped with AC charging ports, so the charging speed will naturally not be faster. Therefore, there is a saying in the industry that AC slow charging and DC fast charging.
Therefore, for the owners of electric vehicles who have just used electric vehicles, here is a simple method to estimate the charging time of the car. During the charging process of the car, wait for the output current and voltage to be stable on the display interface of the charging pile. At the time of charging, look at the output voltage value and current value, calculate the output power, and then compare the amount of electricity your car is ready to charge, you can roughly calculate the time required for charging.
2. Influence of the vehicle on-board charger
During the AC charging process of the vehicle, the on-board charger will participate in the current conversion process. Usually the alternating current will be converted into direct current by the on-board charger as electrical energy and stored in the power battery. Therefore, for the design of the vehicle-mounted charger of the whole vehicle, its power needs to be matched with the AC output power, which is generally around 3.3kw. Even if a higher-power charging pile is used, the output current can only be around 16A, and the charging speed cannot be accelerated. , but it is foreseeable that with the increase of the battery power of electric vehicles, the power of the car charger should be above 6.6kw in the future to ensure the user’s minimum demand for charging speed. The charging of electric vehicles can reach 220V/32A. After understanding, the power of the on-board charger can reach 6.6kw, and the charging speed is much faster than that of the E150EV.
And if the DC charging method is adopted, due to the different interface from the AC charging, the DC power is directly stored in the power battery as electric energy, and the charging speed is naturally much faster without going through the on-board charger. However, in order to ensure battery life and avoid overcharging and overdischarging, the car factory will set the BMS (battery management system) of the vehicle power battery. For example, the charging rate of BYD E6 operating in Shenzhen is about 0.5C (E6 charging voltage and current 326V) /100A).
3. Influence of power battery
Under the condition that the output fixed power of the charging pile is the same, the greater the power of the power battery of the vehicle, the shorter the charging time. The longer it is, it is like a math problem for elementary school students. The same diameter of the water pipe is used to pour water into the pool. The larger the pool, the longer it takes to fill with water. The reason is relatively simple.
In addition, the energy density of the ternary material lithium battery is generally higher than that of the lithium iron phosphate battery, so for the same vehicle, if the driving range is the same, the ternary battery must be installed less than the iron lithium battery. , the charging speed is naturally faster.
There is also a phenomenon that friends in the north will feel more deeply, that is, the car cannot be charged in winter, or the charging speed is maddeningly slow, what is going on? This is related to the chemical characteristics of the battery itself, which is the so-called low temperature protection. When the temperature is too low, the metal lithium in the battery will deposit and no longer chemically react with the substance, resulting in a short circuit inside the battery. In particular, the low temperature performance of lithium iron phosphate batteries is relatively poor. According to related materials, the capacity retention rate at 0 °C is about 60-70%, at -10 °C is 40-55%, and at -20 °C is 20-40%. %, the ternary battery is slightly better than lithium iron phosphate. In the past, some electric car users needed to drive the car out for a few laps to warm up the car to recharge. It is estimated that the electric car hot car will only happen in the northern region, but now most car manufacturers have battery heating modules. When charging and heating, and activating the battery during the charging process, the power will naturally consume a lot. In short, the slow charging speed in winter is certain, but the solutions and efficiency of different car manufacturers will be slightly different. Car owners should ask carefully about this problem before buying a car.
4. Other influencing factors
Here are the influencing factors of power load, especially in summer, when every household turns on air conditioners or other high-power equipment , the transformer load reaches a peak, and the voltage will drop, which will also affect the charging speed of the electric vehicle. However, regular residential areas are generally dedicated transformers, which have a limited impact on the charging speed, while some self-built houses, urban villages and other users generally consume electricity from regional public transformers, which has a greater impact. Therefore, for electric vehicle users, it is recommended to choose to charge during the valley period, and the charging speed will be faster.
