Lead-Acid (AGM / Gel / Flooded)
Battery Chemistries · 9 specs
Direct Answer
Lead-Acid is the oldest rechargeable battery chemistry (invented 1859), delivering 2.0V per cell (12V nominal in standard 6-cell monoblocs). Despite low gravimetric energy density (30–50 Wh/kg), its unmatched surge current delivery (hundreds of cold cranking amps), low production cost, and 99% recycling rate make it the universal standard for automotive starting/ignition (SLI) and industrial UPS systems.
Source: SAE J537 / IEC 60095 · Last reviewed Aug 28, 2026
Specs
| Nominal Cell Voltage | 2.00 (12.00 V 6-Cell Pack) V |
| Gravimetric Energy Density | 30 – 50 Wh/kg |
| Volumetric Energy Density | 60 – 100 Wh/L |
| Cycle Life (to 80% Capacity) | 300 – 1,000 (Deep Cycle AGM) Cycles |
| Thermal Runaway Threshold | > 200 °C |
| Operating Temperature Range | -20 to +50 °C |
| Self-Discharge Rate | 3 – 5% / Month |
| Primary Anode Material | Porous Sponge Lead (Pb) |
| Primary Cathode Material | Lead Dioxide (PbO2) in Sulfuric Acid Electrolyte (H2SO4) |
Flooded vs. AGM vs. Gel Formats
Traditional flooded lead-acid requires periodic distilled water replenishment and upright mounting. Valve-Regulated Lead-Acid (VRLA) designs immoblize the sulfuric acid electrolyte either in an Absorbent Glass Mat (AGM) or a silica-gel suspension (Gel). AGM batteries provide lower internal resistance, faster charging, and vibration resistance required for start-stop automotive systems.