Lead-Acid Battery Technical Guide: 4 Key Parameters for Optimal Performance

Introduction

Understanding core technical parameters is critical when selecting lead-acid batteries (especially gel or lead-carbon types).  This guide breaks down rated voltage, max charge/discharge currents, depth of discharge (DOD), cycle life, and power calculations to help you optimize battery lifespan and system design.

1.  Rated Voltage

Battery voltage is higher under no-load conditions and decreases under load.

Sudden large-current discharge causes immediate voltage drop.

Voltage vs. State of Charge (SOC) maintains an approximately linear relationship only under no-load conditions.

The following are the reference values of the battery voltage and remaining capacity of the battery:

2.  Maximum Charge/Discharge Currents

? Current Calculations (C-rate):

C = Battery Capacity (Ah).

Example: Capacity C=100Ah, 0.15C = 0.15 × 100 = 15A.

⚡ Specific Battery Limits:

Battery TypeMax Charge CurrentMax Discharge Current

Gel Lead-Acid0.15C~3I₁₀ (e.g., 3 × 25A = 75A for C₁₀=250Ah)

Lead-Carbon0.25C₁₀*30I₁₀*

* Example:

Charging: 0.25C₁₀ = 0.25 × 250Ah = 62.5A

Discharging: 30I₁₀ where I₁₀ = C₁₀/10 = 25A → 30 × 25A = 750A

⚠️ System Design Rules (Original Calculations):

Charging Current (Component-dependent):

*5kW system + 48V battery* → Max charging current ≈ 100A

Ordinary lead-acid (0.1C): Min. capacity = 1000Ah

Lead-carbon (0.25C): Min. capacity = 400Ah

Discharging Current (Load-dependent):

*10kW load + 48V battery* → Max discharge current = 200A

Lead-carbon battery(30I₁₀): Min. capacity = >80Ah

Gel battery (3I₁₀): Min. capacity = 800Ah

3. Depth of Discharge (DOD) & Cycle Life:

Shallow Cycle: 10-30% DOD

Medium Cycle: 40-70% DOD

Deep Cycle: 80-90% DOD

⏳ Cycle Life Data :

Battery TypeCycle Life

Traditional Stationary500-600 cycles

Starter Battery300-500 cycles

VRLA Battery1000-1200 cycles

Lead-Carbon Example :

DODCycle LifeService Life

50%4,880>12 years

70%3,760>10 years

100%998<3 years

? Key Insight: Optimal DOD = 60-70%

4. Battery Power Calculation

Theoretical Power = Voltage × Capacity

Example: 12V 250Ah → 12 × 250 = 3,000Wh (3kWh)

Actual Usable Power = Theoretical Power × DOD

Example: 70% DOD → 3,000Wh × 0.7 = 2,100Wh (2.1kWh)

Summary of Unchanged Data Points:

All C-rate calculations (0.15C, 0.25C₁₀, 30I₁₀)

System design examples (5kW/48V=100A, 10kW/48V=200A)

Capacity requirements (1000Ah, 400Ah, 800Ah)

Cycle life numbers (4,880 / 3,760 / 998)

Power calculations (3kWh theoretical → 2.1kWh usable)

Lead-carbon batteries offer superior performance in high-current scenarios (0.25C charging, 30I₁₀ discharge) and extended cycle life at partial DOD.  For systems with space/weight constraints or dynamic loads, they provide a 40-60% capacity reduction advantage over gel batteries.  Always match DOD to your cycle life requirements to maximize ROI.