Modular battery packs solve electric vehicle range fear

    Looking at the various new energy vehicles that have been launched on the market, whether it is a plug-in hybrid (PHEV) or a pure electric vehicle, there is basically no room for consumers to choose "battery capacity". The only one that has this skill is Tesla's Model S, which has two different versions of 60 kWh and 85 kWh. There is no doubt that the electric range is a crucial factor for users to consider whether to buy electric vehicles. If the electric range of a model cannot meet the use requirements, then you can only say goodbye with regret.

    You said that today's traditional power vehicles basically have different power options to choose from, why don't electric vehicles learn this?

Power options for electric vehicles

    A group of scientists from the German Aerospace Center (DLR) had this question and quickly launched a survey on this topic in Germany. The results of this survey made them call on automakers: If you want to promote the development of the new energy vehicle market and increase the sales of PHEV or EREV (extended-range electric vehicles), then you should develop modular battery design as soon as possible so that a model can have different capacity versions, so that customers with different needs can choose accordingly. Instead of "forcing" customers to accept cars with set ranges, and then "fooling" them into buying them in various ways. This is also very helpful for promoting the development of electric vehicles.

    Before them, countless pioneers have studied the impact of battery capacity on PHEVs on their operating costs and CO2 emissions, but DLR researchers believe that some key factors are missing in these studies:

    1. Previous studies have not calculated different driving behaviors separately. It should be noted that energy loss is different under different driving behaviors;

    2. They fail to consider that people with higher annual mileage spend more time on the highway, which means they spend most of their time driving faster than people with lower annual mileage, and the speed difference affects energy loss;

    3. So far, no one has considered the technical differences between different hybrid structures, such as parallel and series hybrid structures, and how they affect the final power conversion efficiency;

    4. In some studies, the battery degradation and aging process is not taken into account, which means that as the battery capacity decays, the energy they consume and the energy conversion rate are also different.

    In short, previous studies have more or less neglected some factors: the impact of different driving behaviors, the impact of battery capacity degradation, and the impact of different hybrid technologies. Therefore, the DLR research team focused on these influencing factors.

The larger the battery capacity, the greater the energy consumption as the mileage increases?

    The research team conducted a study on the German market to calculate the lowest cost of use for new energy vehicles in the form of PHEV and EREV, and also took into account the carbon dioxide emissions of these models. The data analyzed in the study, such as energy loss and battery costs, are based on existing models.

    The reason why there are two categories, PHEV and EREV, is because these researchers believe that among all the electric drive vehicle categories that can replace traditional power, PHEV and EREV are the two most promising types of success because they combine the characteristics of zero emissions of electric vehicles and unlimited cruising range of traditional power vehicles.

    In the study, they selected three typical driving behaviors in Germany: A - 7,500 kilometers per year, B - 15,000 kilometers per year, and C - 30,000 kilometers per year.

Car cost

    The research results show that:

    1. The larger the battery capacity, the higher the energy consumption of PHEV will be than that of EREV, and the difference is more obvious with the larger battery capacity;

    2. In the power system, the higher the proportion of electric drive, the lower the cost per unit of energy consumed as the battery capacity increases;

    3. For a fixed battery capacity, the higher the user's driving mileage, the higher the unit energy consumption cost;

    4. In the three cases of A, B and C, for EREV, the cost is lower when the battery capacity is 2.0 kWh, 6.0 kWh and 13.0 kWh, and their corresponding electric ranges are 8 km, 24 km and 51 km respectively.

    5. In PHEV, the lowest cost consumption is when the battery capacity is 1.5 kWh, 3.5 kWh and 5.0 kWh (corresponding to cases A, B and C).

    It can be seen that the choice of battery capacity is a key factor in meeting customer needs and competing with traditional power in terms of cost. Researchers said that automakers do not need to make mistakes because of this, but only need to provide three types of battery capacities, large, medium and small, according to different mileages to basically meet the needs of most people. The modular design of battery packs will help automakers meet the changes in vehicle models with less cost and less modification of other parts of the car.

    According to the survey, the researchers also came to a conclusion: the higher the battery capacity, the lower the overall CO2 emissions. If reducing greenhouse gases, that is, environmental protection, is the main goal for the government, then automakers can be encouraged to develop high-capacity battery packs (whether PHEV or EREV).

    There are two different ways to achieve this result:

    1. From the user's perspective, financial subsidies can be used to directly reduce the cost of purchasing electric vehicles, or corresponding tax exemptions can be set according to the battery capacity to reduce the user's car purchase burden. For traditional power vehicles, the price can be increased by increasing the corresponding taxes.

    2. From the perspective of automakers, a provision can be added to local CO2 emission regulations: for these partially zero-emission vehicles, the reduction of CO2 emissions can be subsidized according to the electric driving range (just like the zero-emission regulations implemented in California). Of course, in the end, the electricity used for PHEVs to drive in pure electric mode should be generated by renewable energy to be completely beneficial to the environment.

    It should be noted that in this study, the evaluation object is an idealized, rational consumer, whose choice is based on minimizing the cost of use. However, in reality, our purchasing behavior cannot be completely rational. We may decide what car to buy based on the appearance or the long-distance travel that we rarely take. The DLR research team will continue to study this and analyze how consumers choose an electric car in real situations, and will select the most influential factors and the final results through research.

Someone sent me a pillow when I was sleepy

    It hasn’t been long since DLR’s research results were released and there has been a response over there.

    At the end of September, Boston Energy, a lithium battery manufacturer, released its latest technological achievement: a modular battery pack using standardized components, the Ensemble Module System, which can provide automakers or battery assembly suppliers with a simpler and lower-cost method to assemble large-capacity battery packs.

    How does the Ensemble modular system achieve battery modularity? The key is that Boston Energy uses a novel pressure connection method to assemble modules, rather than the traditional welding method that is both time-consuming and cost-intensive. The system has now been fully tested to OEM standards, and the test results show that it can be assembled or disassembled in a shorter time than traditional methods, while having the same assembly density, reliability, and thermodynamic performance as traditional methods. In other words, this method does not reduce the performance and reliability of the battery, and of course, it does not improve it. Its biggest advantage is quick assembly and disassembly. The weight energy density of a 5300 mAh, 19.3 Wh battery cell is 207 Wh/kg, and the volume density is 490 Wh/L.

Ensemble Module System

    The modular battery technology is based on a flat, prismatic-shaped battery cell that is the size of two 18650-size lithium-ion battery cells. Boston Energy calls the Swing 5300 battery cell, which can be used in pure electric vehicles, plug-in hybrids, light commercial vehicles, community electric vehicles, and energy storage systems.

    For automakers, if they want to design large-capacity battery packs, they usually have to spend a lot of time on battery pack design, safety and qualification certification, and even customize special solutions for users to meet different usage requirements. The existence of the Ensemble modular system is equivalent to providing a semi-customized battery unit. Automakers only need to choose the capacity to achieve rapid production and assembly, which can save most of the time from concept verification to marketization, and can also reduce initial investment, project risks, labor costs, etc.

    What car manufacturers need to do is to create several battery modules of different sizes for their users to choose from based on previous user usage data.