Batteries are the core component of electric vehicles, and their importance is obvious. Therefore, we need to understand the composition and parameters of lithium batteries better.
The Main Composition of a Lithium Battery Pack
A lithium battery pack mainly consists of multiple battery modules and a Battery Management System (BMS).
What’s a Lithium Battery Pack?
It is generally composed of multiple battery modules, and at the same time, a Battery Management System (BMS) is also added, which is the final product provided by the battery factory to users.
Composition of Lithium Battery Packs
Lithium battery packs consist of modules connected in parallel and series, and modules consist of cells connected in parallel and series.
A cell is a single battery, composed of electrodes and electrolytes, and it’s the smallest unit of a lithium battery pack. It can store electrical energy in the form of chemical energy and convert chemical energy into electrical energy. The cell voltage is usually 3.2V, so the golf cart lithium battery is usually a multiple of 3.2V.
Lithium Battery Cell
What’s BMS?
The Battery Management System (BMS) can be regarded as the “brain” of the battery. It is mainly composed of the BMU, MBMS, and BAMS. It’s a circuit system used to manage the charging and discharging process of the battery, improve the service life of the battery, and provide users with relevant information.
BMU
The BMU has the function of monitoring the voltage and temperature of the single battery in the battery module. It can safely manage the charging and discharging process of the battery module and provide a communication interface for the battery.
The BMU is the smallest management unit of a Battery Management System (BMS). It provides internal information about battery modules to the battery cluster management system (MBMS) through communication interfaces.
MBMS
The MBMS is a real-time detection and management system composed of electronic circuit equipment. It can effectively manage the battery cluster charging and discharging process safely, provide alarms and emergency protection for possible faults, and ensure the safe, reliable, and stable operation of the battery.
The MBMS collects information from the Battery Management Unit (BMU) and provides it to the upper battery Stack Management System (BAMS).
BAMS
The BAMS is a real-time detection and management system composed of electronic circuit equipment, which centrally manages the battery of the entire energy storage system to ensure the safe, reliable, and stable operation of the battery. BAMS is the highest level of the Battery Management System, connected to the Battery Cluster Management System (MBMS).
The Technical Parameters of Lithium Battery Pack
The Nine Types of Golf Cart Batteries from HIITIO:
| Lead-Acid Battery Voltage | Lithium Battery Voltage | Capacity 1 | Capacity 2 | Capacity 3 |
|---|---|---|---|---|
| 36V | 38.4V | 105Ah | 150Ah | 230Ah |
| 48V | 51.2V | 105Ah | 150Ah | 230Ah |
| 72V | 73.6V | 105Ah | 150Ah | 230Ah |
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72V 230Ah LiFePO4 Golf Cart Battery -
72V 150Ah LiFePO4 Golf Cart Battery -
72V 105Ah LiFePO4 Golf Cart Battery -
48V 230Ah LiFePO4 Golf Cart Battery -
48V 150Ah LiFePO4 Golf Cart Battery -
48V 105Ah LiFePO4 Golf Cart Battery -
36V 230Ah LiFePO4 Golf Cart Battery -
36V 150Ah LiFePO4 Golf Cart Battery -
36V 105Ah LiFePO4 Golf Cart Battery
Battery Capacity
Battery capacity is the amount of electricity a battery can store, which is the core indication of battery performance. Capacity depends on the active substances in the electrodes.
- Unit: Ah or mAh
- Formula:
( C = I \cdot t )
Capacity (Ah) = Current (A) × Discharge Time (h)
Battery Energy
Battery energy is the energy stored in a battery.
- Formula:
( \text{Energy (Wh)} = \text{Rated Voltage (V)} \cdot \text{Discharge Current (A)} \cdot \text{Discharge Time (h)} )
Energy Density
The energy a battery can store per unit volume or weight.
- Units: Wh/L or Wh/kg
- Typical Value: 150Wh/kg
Discharge Rate
Discharge rate refers to the current required to release the rated capacity of the battery within a specified time, usually equal to ( n \cdot C ).
Self-Discharge Rate
The self-discharge rate of a battery refers to the rate at which the battery loses charge on its own when it is not charging or discharging. In other words, the battery’s power will slowly decrease even if it is not used.
- Lithium Battery Self-Discharge Rate: <4% per month
- Lead-Acid Battery Self-Discharge Rate: ~30% per month
Cycle Life
- Lead-Acid Battery: 600-800 cycles (2-3 years)
- Lithium Battery: ~4000 cycles (10 years)
Memory Effect
The memory effect of a battery refers to the percentage that a battery that is not fully charged can be charged the next time.
- Lead-Acid Batteries: Have a memory effect. They should be fully charged every time and do not support gap charging or multiple shifts of continuous operation. Otherwise, the battery capacity will decrease.
- Lithium Batteries: Do not have a memory effect. They can be intermittently charged and support multi-shift continuous operation.
