1. Different voltage levels
In the battery industry, an increase in voltage leads to an increase in the corresponding output voltage, enabling power lithium-ion battery packs to meet the needs of some high-power devices. The direct result of parallel connection is an increase in the current of the entire battery pack. Since capacity is affected by the output current, the direct purpose of parallel connection is to increase the capacity of lithium-ion battery packs. Battery packs connected in this way often have a larger capacity, which is the so-called capacity-type lithium-ion battery pack.
Power lithium batteries are primarily used for energy storage, requiring large capacity, long lifespan, and low self-discharge. Power tool batteries have smaller capacities and do not need to provide high power output; while energy storage batteries are mainly used for power supply and require the ability to output high power.
2. Different products are used.
Some large equipment requires higher voltage values because low-power battery packs cannot operate it, so high-capacity lithium-ion battery packs are used. For example, the electric bicycles we use every day often require a voltage of 48V, which is quite high for most everyday situations. Therefore, high-capacity lithium-ion battery packs are necessary to ensure the operation of electric bicycles. On the other hand, in large supermarkets or shopping malls, some sign lights and backup power supplies generally use high-capacity lithium-ion battery packs because their power consumption is not very high. These two types of equipment have different applications.
The lithium-ion batteries used in BYD's electric vehicles and new energy vehicles are all power lithium-ion batteries, which are classified into three types according to their characteristics: power type, energy type, and power-energy balanced type. The key characteristic of power lithium-ion batteries, as you mentioned, is their ability to support high-rate charging and discharging, generally exceeding 10C. A crucial parameter is their specific energy (W/kg). The key characteristic of energy type batteries is their higher specific energy (Wh/kg). To illustrate, capacity-type batteries are like marathon runners, requiring endurance and thus high capacity, with generally lower requirements for high-current discharge performance. Power-type batteries are like sprinters, relying on explosive power, but endurance is also necessary; otherwise, insufficient capacity will limit their range.
