Interest in electric vehicles is growing as the government has aggressively promoted new energy vehicles in recent years. Streets can always hear people talking about electric vehicles, talking about electric vehicles the first topic can not get around is charging, because it directly determines the user experience. At present, the charging pile is divided into AC charging pile and DC charging pile two kinds, one fast and one slow. From the perspective of AC pile, most of the slow charging piles or charging boxes in China use 220v AC charging, the output current is 16A or 32A, the theoretical power can reach 3.3kW or 6.6kW, considering the 10% power loss, the AC charging speed is still very slow. Let's take a look at why the charging speed of electric vehicle charging pile is not the same!
1. The impact of charging piles
In simple terms, the higher the output power of the charging pile, the shorter the charging time, but the charging pile is currently divided into AC charging pile and DC charging pile, we can explain it separately.
From the perspective of AC pile, most of the slow charging piles or charging boxes in China use 220v AC charging, the output current is 16A or 32A, the theoretical power can reach 3.3kW or 6.6kW, considering the 10% power loss, the AC charging speed is still very slow. For example, for electric vehicles with a general battery power of about 20kWh, the current mainstream 3.3kW AC charging method takes 6-8 hours to be fully charged. For Tesla 220v HPWC(high power wall mount adapter) output current up to 50A, output power 11kW, we still do not have to think,
Therefore, for the owners of electric vehicles, here can provide you with a simple estimate of the car charging time, in the car charging process, such as the charging pile display interface output current, voltage is stable, look at the output voltage value and current value, calculate the output power, and then compare the car ready to charge the electricity, you can roughly calculate the need for charging Time.
2, the impact of the vehicle charger
In the AC charging process of the vehicle, the vehicle charger will participate in the current conversion process, usually the AC will be converted into direct current through the vehicle charger as electrical energy stored in the power battery. Therefore, for the vehicle charger design, its power needs to match the AC output power, generally around 3.3kW, even with higher power charging pile output current can only be about 16A, charging speed is not fast, but it is foreseeable that with the increase of electric vehicle battery power, the future car charger power should be in 6.6kW In order to ensure the user's minimum demand for charging speed. Once in the process of investigating the charging pile, it was found that the Saab electric vehicle charging can reach 220V/32A, after understanding that the car charger power can reach 6.6kW, charging speed is much faster than E150EV.
If the DC charging method is used, due to the different interface with AC charging, DC as electrical energy is directly stored in the power battery, without going through the car charger, the charging speed is naturally much faster, but 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, in Shenzhen The charging ratio of BYD E6 is about 0.5C (E6 charging voltage and current 326V/100A).
3, the impact of the power battery
In the case of the same fixed power output at the end of the charging pile, the larger the vehicle power battery, the longer the charging time, which is like a math problem for primary school students in general, in the same caliber of water discharge pipe to the pool, the larger the pool, the longer it takes to fill the water, this truth 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 model, if the driving range is required to be consistent, the ternary battery must be less than the lithium iron phosphate battery, and the charging speed is naturally faster.
There is a phenomenon that friends in the north will feel more deeply, that is, when the car is not charged in the winter, or the charging speed is maddening, how is this? This is related to the chemical characteristics of the battery itself, that is, the so-called low-temperature protection, in the case of too low temperature, the metal lithium in the battery will produce deposition phenomenon, no longer chemical reaction with the substance, resulting in the internal short circuit of the battery. In particular, it should be mentioned that the low temperature performance of lithium iron phosphate batteries is relatively poor, according to relevant materials, its capacity retention rate at 0 ° C is about 60 ~ 70%, 40 ~ 55% at -10 ° C, 20 ~ 40% at -20 ° C, and the ternary battery is slightly better than the lithium iron phosphate battery. In the past, some electric vehicle users need to drive the car to run a few laps to charge the hot car, it is estimated that the hot car of electric vehicles will be in the northern region, but now most of the car manufacturers have battery heating modules, charging while heating in the cold, activate the battery during the charging process, electricity will naturally cost a lot. In short, the slow charging speed in winter is certain, but the solutions and efficiency of different automakers will be slightly different, and the owners of this problem should be carefully asked before buying a car.
4. Other influencing factors
Here mentioned the factors affecting the power load, especially in the summer, every household open air conditioning or other high-power equipment, transformer load reaches a peak, the voltage will decline, which will also affect the charging speed of electric vehicles. 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 of electricity generally come from regional public transformers, and the impact is greater. Therefore, for electric vehicle users, it is recommended to choose the electricity valley to charge, charging speed will be faster.
