1. The "fragility" of lithium batteries needs protection
Lithium batteries are extremely sensitive to the following situations:
Overcharge: Voltage exceeding the upper limit will cause electrolyte decomposition, gas production, and even explosion.
Overdischarge: Voltage below the lower limit will destroy the negative electrode structure, resulting in irreversible attenuation of battery capacity.
Overcurrent/short circuit: High current will cause internal short circuit, resulting in heating and fire.
Abnormal temperature: High temperature will accelerate side reactions, and low temperature may cause lithium deposition (dendritic growth).
The core role of BMS:
Real-time monitoring of voltage, current, and temperature.
Cut off charging and discharging in dangerous conditions through control circuits (such as MOSFET switches).
Two-wheeler/three-wheeler protection board
2. Consequences of not having BMS: catastrophic risks
Battery damage: A single overcharge/overdischarge can cause the battery to be scrapped.
Thermal runaway: Short circuit or high temperature may trigger a chain reaction, leading to combustion or explosion (such as the Samsung Note7 incident).
Legal risks: Most countries require lithium battery products to pass safety certification (such as UL, CE), and BMS is a key part of the certification.
3. "Necessary" scenarios for BMS
Consumer electronics: Mobile phones and notebooks must have built-in BMS (usually integrated in the battery pack).
Power batteries: Electric vehicles and energy storage systems require more complex BMS (including balancing functions).
DIY battery packs: Even single-cell 18650 batteries need to be connected in series/parallel through protection boards.
4. Exceptions and precautions
Special industrial applications: BMS may be omitted in very few customized scenarios (such as aerospace-grade batteries), but safety must be ensured through other redundant designs.
Risk of counterfeit products: Some low-priced lithium batteries may omit BMS or use inferior components, which poses serious safety risks.
5. How to choose BMS?
Match battery parameters: Choose according to battery type (such as ternary lithium/lithium iron phosphate), voltage, and capacity.
Functional requirements: basic protection (overcharge/over discharge/short circuit) or advanced functions (balancing, communication, temperature control).
Certification standards: products with safety certifications such as UL and IEC are preferred.
