Professional Perspectives on Flooded vs. Valve Regulated Lead-Acid Batteries
Lead-acid batteries are primarily classified into two major types based on electrolyte content and structural design: Flooded Lead-Acid Battery and Valve Regulated Lead-Acid Battery (VRLA). The following provides a detailed distinction between the two from multiple professional perspectives:
I. Definition and Basic Characteristics
Flooded Lead-Acid Battery
Definition: The interior is filled with liquid sulfuric acid and distilled water, with ample electrolyte capacity, ensuring the plates are fully immersed in the electrolyte.
Characteristics:
Utilizes an open or semi-open design with ventilation ports.
Requires regular maintenance (e.g., refilling water, checking electrolyte specific gravity).
Electrolyte flows freely, and gases are discharged through ventilation ports.
Relatively low cost but high maintenance demands.
Valve Regulated Lead-Acid Battery (VRLA)
Definition: The electrolyte is entirely absorbed into the micropores of the plates and separators, with spaces between the electrodes not completely filled by the electrolyte.
Characteristics:
Sealed design equipped with a safety valve (pressure regulation valve).
Maintenance-free, no need for periodic fluid replenishment.
Oxygen recombination reaction minimizes electrolyte evaporation.
Electrolyte is immobilized (via AGM or gel technology), with no free liquid.
II. Structural Design Differences
| Features | Flooded Lead-Acid Battery | Valve-Regulated Lead-Acid Battery (VRLA) |
| Electrolyte State | Free-flowing liquid electrolyte | Electrolyte immobilized (AGM or gel) |
| Vent Design | Equipped with vents to allow gas release | Sealed design with pressure-controlled safety valves |
| Plate Spacing | Larger, allowing gas diffusion | Smaller, promoting oxygen recombination |
| Separator Material | Ordinary separator | Absorptive Glass Mat (AGM) or Gel Separator |
| Maintenance | Requires regular water replenishment | Maintenance-free |
III. Performance Comparison
Cycle Life:
Flooded: Can exceed 10 years with proper maintenance, but improper maintenance significantly shortens lifespan
AGM (Absorbent Glass Mat): Designed lifespan typically 5-8 years, but may fail prematurely due to water loss in practice
Charge/Discharge Characteristics:
Flooded: Capable of withstanding high-current discharge, suitable for high-power applications
AGM: Higher charge/discharge efficiency (50%-95%), but slightly inferior high-current performance
Environmental Adaptability:
Flooded: Requires good ventilation, cannot be installed upside down
AGM: Can be installed horizontally, space-saving, suitable for confined environments
Self-Discharge Rate:
Flooded: 3%-20%/month
AGM: Slightly lower than flooded type
Cost:
Flooded: Low initial cost but high maintenance cost
AGM: High initial cost but maintenance-free
IV. Application Scenarios
Flooded Lead-Acid Battery Applicable Scenarios
Automotive Starting Batteries (Traditional Fuel Vehicles)
Industrial Backup Power
Industrial Vehicles such as Forklifts
Applications Requiring High Power Output
Cost-Sensitive Applications with Acceptable Regular Maintenance
Valve-Regulated Lead-Acid Battery Applicable Scenarios
Electric Bicycles and Motorcycles
UPS Uninterruptible Power Supply Systems
Backup Power for Communication Base Stations
Emergency Lighting Systems
Maintenance-Free or Space-Constrained Applications
Vehicle Start-Stop Systems (AGM Batteries)
V. Technology Development Trends
Flooded Battery Improvements:
Enhanced Flooded Battery (EFB) improves performance through structural optimization
Automatic watering systems reduce maintenance requirements
VRLA Battery Developments:
AGM technology enhances cycle life
Gel batteries extend service life by over 30%
More precise safety valve control technology