I. Basic Knowledge of 24V Lithium-Ion Batteries

(1) Classification of Mainstream Chemical Systems

• Lithium Iron Phosphate (LFP): It has high safety (thermal runaway temperature > 800℃) and a long cycle life (2000-6500 cycles), but its energy density is relatively low (100-160Wh/kg). It is suitable for industrial equipment, special equipment, and other scenarios that require high stability.
• Ternary Lithium (NCM): It features high energy density (200-300Wh/kg) and excellent low-temperature performance (discharge efficiency > 70% at -20℃), but it has higher cost and requires strict temperature control. It is applicable to mobile devices sensitive to volume and weight, such as robots and surveying/mapping equipment. Lithium cobalt oxide (LCO) is not recommended for industrial-grade applications due to its short cycle life (< 500 cycles) and poor safety.

(2) Core Advantages of 24V Lithium-Ion Batteries

1. Lightweight and High Energy Density: Under the same capacity, their volume is 50% smaller and weight is 60% lighter than lead-acid batteries, making them more suitable for equipment with compact space.
2. Long Service Life and Low Cost: Their cycle life is 3-5 times that of lead-acid batteries, and the total life-cycle (5-8 years) usage cost is reduced by more than 40%.
3. Intelligent Management and Safety: The built-in BMS (Battery Management System) provides overcharge, over-discharge, and over-temperature protection, supports remote status monitoring, and reduces the equipment failure rate by 70%. 

II. Core Technologies for Custom 24V Lithium-Ion Batteries

(1) Core Customization Parameters

Voltage Parameters

• Lithium Iron Phosphate: 8 cells connected in series, with a nominal voltage of 25.6V, a maximum charging voltage of 29.2V, and a minimum discharging voltage of 20V (cells are prone to damage below this value).
• Ternary Lithium: 7 cells connected in series, with a nominal voltage of 25.9V, a maximum charging voltage of 29.4V, and a minimum discharging voltage of 21V.

Capacity Parameters

• Actual Usable Capacity = Nominal Capacity × 80% (a 20% safety margin is reserved to avoid deep discharge). For example, a 100Ah battery is recommended to be used within 80Ah in practice.

Service Life Parameters

• Cycle Life: Based on the standard of capacity fading to 80%, lithium iron phosphate batteries have a cycle life of ≥ 2000 times, and ternary lithium batteries have ≥ 800 times.
• Calendar Life: It can reach 5-8 years when stored at room temperature (25℃), and regular charge-discharge maintenance is required.

(2) Structural Design Solutions

Cell Combination Method

• Series connection determines the voltage (8-series for lithium iron phosphate / 7-series for ternary lithium).
• Parallel connection increases the capacity (e.g., 2 parallel 100Ah cells achieve a total capacity of 200Ah).

Size and Shape

• Small Equipment (5-50Ah): 18650/21700 cylindrical cells or pouch cells are used, suitable for handheld devices and small sensors.
• Medium and Large Equipment (100-500Ah): Prismatic aluminum-shell cells are used, supporting modular customization.

Shell Material and Protection Design

• Material: Aluminum alloy (strong heat dissipation, suitable for high-power equipment) or ABS engineering plastic (lightweight, suitable for normal-temperature scenarios).
• Protection Level: IP65 or above is required for outdoor/humid scenarios (e.g., IP67 for short-term water immersion), and a dust filter should be installed in dusty environments.

Heat Dissipation Design

• For high-power equipment (discharge current > 50A), built-in thermal conductive silica gel or aluminum heat sinks are required to ensure the temperature difference between cells is < 5℃ during operation and prevent local overheating.

(3) BMS Function Customization

Basic Protection Functions

• Overcharge protection (voltage accuracy ±0.02V), over-discharge protection (voltage accuracy ±0.1V), overcurrent protection (response time < 5ms), and short-circuit protection (automatic power-off after triggering).

Advanced Management Functions

• Active Balancing: Dynamically balances the voltage of each cell (voltage difference < 50mV), extending the overall battery life by more than 15% (recommended as a priority for industrial equipment).
• Communication Protocols: Supports SMBUS/I2C/CAN buses to realize power monitoring and fault early warning. In some scenarios, OTA (Over-the-Air) remote parameter updating is supported (e.g., security equipment, rail transit monitoring equipment).

(4) Safety Design and Compliance Certification

Safety Design

• Hardware: Insulation partitions are installed between cells (withstand voltage > 500V), and explosion-proof valves are reserved on the shell (automatic pressure relief when internal pressure > 1.2MPa).
• Software: The BMS adopts a dual redundancy design (independent monitoring by main and secondary chips) to prevent protection failure caused by a single point of failure.

Compliance Certification

• Basic Certification: For domestic sales, CQC certification (complying with the GB 31241-2014 standard) is required; for export, UL 1642 (U.S.) and IEC 62619 (international energy storage/industrial standard) are required.
• Industry-Specific Certification: Medical equipment requires CE-MDD and ISO 13485 (biocompatibility); rail transit equipment must comply with EN 50155 (wide temperature range and vibration requirements).

Key Points to Avoid Pitfalls in Selection

Misunderstanding 1: Focusing Only on Capacity and Ignoring Discharge Rate

• Risk: Some batteries are labeled 100Ah, but their continuous discharge current is only 1C (100A), which cannot drive industrial robotic arms requiring 2C (200A) instantaneous power, leading to equipment startup failure.
• Solution: Clarify the maximum discharge current of the equipment, and require suppliers to provide discharge rate curves (e.g., the 2C discharge capacity should be ≥ 90% of the nominal capacity).
• Applicable Scenarios: High-power, vibration-resistant equipment (e.g., AGV robots, robotic arms).