Introduction：
Lithium batteries are everywhere in our lives. Our mobile phone batteries and electric car batteries are all lithium batteries, but do you know some basic battery terms, battery types, and the role and difference of battery series and parallel connection? Let's explore the knowledge of batteries with Heltec.
Basic terminology of lithium batteries
1) C-rate
Refers to the ratio of the current to the nominal capacity of the lithium battery during charging and discharging. It describes how fast the battery can be charged and discharged. The charging and discharging rates are not necessarily the same. For example:
1C: fully discharge the battery within 1 hour (full charge)
0.2C: fully discharge the battery within 5 hours (full charge)
5C: fully discharge the battery within 0.2 hours (full charge)
2) Capacity
The amount of electricity stored in the lithium battery. The unit is mAh or Ah.
Combined with the rate, for example, if the battery is 4800mAh and the charging rate is 0.2C, it means that it takes 5 hours for the battery to be fully charged from empty (ignoring the pre-charging stage when the battery is very low).
The charging current is: 4800mA*0.2C=0.96A
3) BMS battery management system
The system controls and manages the charging/discharging of the battery, detects the temperature and voltage of the battery, connects with the host system, balances the battery voltage, and manages the safety performance of the lithium battery pack.
4) Cycle
The process of battery charging and discharging is called a cycle. If the battery only uses 80% of its total energy each time, the cycle life of lithium-ion batteries can be as high as thousands of times.
Lithium Battery Type
Currently, commercial lithium-ion cells are mainly cylindrical, square and soft-pack.
18650 cylindrical cells are the lithium-ion cells with the highest production volume at present. Our G series monitor battery cells are of this type.
Cell series and parallel connection
The cell is the core component of the lithium battery. The number of cells varies depending on the application of the battery, but all batteries need to be connected in different ways to achieve the required voltage and power.
Note: The conditions for parallel connection are very harsh. Therefore, parallel connection first and then series connection can reduce the requirements for battery consistency.
Q: What is the difference between three-series and four-parallel and four-parallel and three-series batteries?
A: The voltage and capacity are different. Series connection increases voltage, and parallel connection increases current (capacity)
1) Parallel connection
Assume that the voltage of the battery cell is 3.7V and the capacity is 2.4Ah. After parallel connection, the terminal voltage of the system is still 3.7V, but the capacity increases to 7.2Ah.
2) Series connection
Assume that the voltage of the battery cell is 3.7V and the capacity is 2.4Ah. After series connection, the terminal voltage of the system is 11.1V, and the capacity remains unchanged.
If a battery cell is three series and two parallel, a total of 6 18650 cells, then the battery is 11.1V and 4.8Ah. Tesla Model-S sedan uses Panasonic 18650 cells, and an 85kWh battery pack requires about 7,000 cells.
Conclusion
Heltec will continue to update the popular science knowledge about lithium batteries. If you are interested, you can pay attention to it. At the same time, we provide you with high-quality lithium battery packs for you to purchase and provide customized services to meet your needs.
Heltec Energy is your trusted partner in battery pack manufacturing. With our relentless focus on research and development, coupled with our comprehensive range of battery accessories, we offer one-stop solutions to meet the evolving needs of the industry. Our commitment to excellence, tailored solutions, and strong customer partnerships make us the go-to choice for battery pack manufacturers and suppliers worldwide.
If you have any questions or would like to learn more, please don't hesitate to reach out to us.
Request for Quotation:
Jacqueline: jacqueline@heltec-bms.com / +86 185 8375 6538
Sucre: sucre@heltec-bms.com / +86 136 8844 2313
Nancy: nancy@heltec-bms.com / +86 184 8223 7713
Post time: Oct-18-2024