The lead acid battery maintains a strong foothold as being rugged and reliable at a cost that is lower than most other chemistries. The global market of lead acid is still growing but other systems are making inroads. Lead acid works best for standby applications that require few deep-discharge cycles and the starter battery fits this duty well. Table 1 summarizes the characteristics of lead acid systems.
Chemistry |
Starter (SLI) |
Deep-cycle |
AGM |
Gel |
Advanced Lead Carbon (ALC) |
Type |
Many thin plates increase the surface for high current delivery, not spill-proof |
Fewer thick plates give high capacity and durability, not spill-proof |
Sulfuric acid is absorbed by a fine fiberglass mat; spill-proof |
Electrolyte is suspended in silica type gel; spill-proof |
Carbon anode improves charge and discharge performance |
Nominal voltage |
2.00V |
2.00V |
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Full charge |
2.45V at ambient, lower when hot |
2.40V, or more |
2.40V, or less |
2.45V |
|
Float charge |
2.30V at ambient, lower when hot |
2.25–2.30V, sensitive to overcharge |
2.30V |
||
Full discharge |
1.75V, must be recharged to prevent sulfation |
1.75V |
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Specific Energy |
30–50Wh/kg |
20–30Wh/kg; some are higher |
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Charge rate |
0.1–0.05C (16h charge time to get for full saturation) |
2–4 times faster |
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Discharge rate |
High momentary current |
Continuous moderate current |
Moderate to high current |
High current |
|
Cycle life |
12–15 |
150–200, longer if not discharged lower than 60% SoC |
5–10 years for UPS |
Better than regular lead acid |
|
Maintenance |
Flooded needs water;16 hour charge every 6 months to prevent sulfation |
Maintenance-free; less prone to sulfation, no water can be added |
Less prone to sulfation |
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Failure modes |
Sulfation, shedding, depletion of active material, corrosion, mechanical |
Unknown |
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Packaging |
Standards to fit vehicle mount |
Standards and unique sizes |
30–100Ah typical; also unique sizes |
Small and large sizes |
Standards to fit vehicles, others |
Environment |
Lead is toxic, electrolyte is caustic |
AGM, gel has less lead, electrolyte; avoid heat, use special charger |
Toxic |
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History |
Oldest rechargeable battery in 1859 by Gaston Planté; coating of lead sheet with lead oxides in 1880 |
Gates Energy, USA, in early 1970s |
Sonnenschein, Germany, patent mid-1950s |
New technology, experimentation, customization |
|
Applications |
SLI (starter, light, ignition) for vehicles |
UPS, wheeled mobility |
Military, aircraft, start-stop, racing, NASCAR, marine |
UPS, wheeled mobility, busses, trucks, industry |
Vehicles, military, energy storage |
Comments |
Well-suited for SLI. Low price; large temperature range |
Ideal for UPS that needs few cycling |
Big seller, cost effective, fast charging, high power but does not transfer heat as well as gel. Performs well when cold. |
High ambient rating, high cycle count, less prone to sulfation, needs correct charge; costly. Tolerant at warm temperatures; low self-discharge. |
Better charge acceptance for regenerative breaking; longer lasting |
All readings are estimated averages at time of publication. More detail can be seen on:
- BU-201: How does the Lead Acid Battery Work?
- BU-201a: Absorbent Glass Mat (AGM)
- BU-202: New Lead Acid Systems.
* AGM and Gel are VRLA (valve regulated lead acid) batteries. The electrolyte has been immobilized.
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