Lead-Acid (AGM / Gel / Flooded) vs. Nickel-Metal Hydride (NiMH)
Comparing 2 standards across 9 specifications. 8 key differences identified.
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.
Nickel-Metal Hydride (NiMH) is the dominant rechargeable consumer chemistry for standard cylindrical battery formats (AA, AAA, C, D). Operating at 1.2V nominal, NiMH provides 60–120 Wh/kg specific energy, eliminates toxic cadmium, and modern Low Self-Discharge (LSD / Eneloop) formulations retain 70–85% of charge after several years of storage.
Specification Comparison Table
9 Parameters| Parameter / Spec | ||
|---|---|---|
|
Nominal Cell Voltage
|
2.00 (12.00 V 6-Cell Pack) V | 1.20 V |
|
Gravimetric Energy Density
|
30 – 50 Wh/kg | 60 – 120 Wh/kg |
|
Volumetric Energy Density
|
60 – 100 Wh/L | 180 – 300 Wh/L |
|
Cycle Life (to 80% Capacity)
|
300 – 1,000 (Deep Cycle AGM) Cycles | 500 – 1,500 Cycles |
|
Thermal Runaway Threshold
|
> 200 °C | > 250 °C |
|
Operating Temperature Range
|
-20 to +50 °C | -20 to +50 °C |
|
Self-Discharge Rate
|
3 – 5% / Month | 10–20% / Month (Standard) | < 1% / Month (LSD) |
|
Primary Anode Material
|
Porous Sponge Lead (Pb) | Hydrogen-absorbing Rare Earth Alloy (AB5 or AB2 Metal Hydride) |
|
Primary Cathode Material
|
Lead Dioxide (PbO2) in Sulfuric Acid Electrolyte (H2SO4) | Nickel Oxyhydroxide (NiOOH) |