Understanding the 8.4V Lithium Battery Configuration

When designing an 8.4V lithium battery pack, engineers typically connect two 3.7V lithium-ion (Li-ion) or 3.6V lithium iron phosphate (LiFePO4) cells in series. This configuration leverages the additive voltage principle – imagine stacking two water buckets to double the flow pressure. The choice between Li-ion and LiFePO4 depends on application requirements:

• Li-ion cells: Higher energy density (250-300 Wh/kg)
• LiFePO4 cells: Superior thermal stability (>200°C operating range)

Key Parameters for Series Connections

Parameter	Li-ion	LiFePO4
Nominal Voltage per Cell	3.7V	3.2V
Cycle Life (80% capacity)	500-1,200	2,000-5,000
Charge Rate (Standard)	0.5C-1C	1C-2C

Industry Applications Driving Demand

The global market for series-connected lithium batteries is projected to grow at 18.3% CAGR through 2030 (Grand View Research). Our recent project for an industrial drone manufacturer demonstrates this trend:

• Client required 8.4V battery with 2.5Ah capacity
• Used matched 18650 cells (3.7V 2500mAh)
• Implemented active balancing circuit
• Achieved 95% capacity retention after 300 cycles

Emerging Trends in Series Battery Packs

Smart battery management systems (BMS) are revolutionizing series configurations. These systems now incorporate:

• Real-time cell monitoring (voltage deviation <50mV)
• Predictive thermal management
• Dynamic charge balancing

Why Choose Our Battery Solutions?

As a custom lithium battery pack manufacturer serving global markets since 2005, we specialize in:

• Precision cell matching (ΔV <20mV)
• UL/IEC certified production
• Custom BMS integration

Contact our technical team: 📞 +86 138 1658 3346 (WhatsApp/WeChat) 📧 [email protected]

FAQ: Series-Connected Battery Packs

Why use series connection for 8.4V?

Series connections allow using standard cell voltages (3.6-3.7V) to achieve higher system voltages without custom cell designs.

What protection circuits are essential?

All series configurations require:

• Overvoltage protection (≥4.25V/cell)
• Undervoltage cutoff (≤2.5V/cell)
• Current limiting (≥1.5× rated current)

Conclusion

Building reliable 8.4V lithium battery packs requires careful cell selection, precise balancing, and robust protection systems. As energy density requirements grow, series configurations continue to dominate mid-voltage applications from power tools to medical devices.

Download Batteries Used in Series for the 8.4V Lithium Battery Pack: A Technical Guide [PDF]

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