An Overview of NiCd, NiMH, Li-Ion, and Lead-Acid Battery Characteristics

Vili Matošević

Power Supply

March 23, 2025

An Overview of NiCd, NiMH, Li-Ion, and Lead-Acid Battery Characteristics

Here is an overview of the characteristics of NiCd, NiMH, Li-ion types, and lead-acid batteries.

  1. Nickel-Cadmium (NiCd) Batteries

Characteristics:

  • Energy Density: Low to moderate (45-80 Wh/kg).
  • Cycle Life: Very high (up to 1,000 charge cycles).
  • Self-Discharge Rate: High (10-15% per month).
  • Memory Effect: Yes, suffers from memory effect if not fully discharged before recharging.
  • Environmental Impact: Contains toxic cadmium, making disposal challenging.
  • Applications: Power tools, aviation, emergency lighting, and older portable devices.
  1. Nickel-Metal Hydride (NiMH) Batteries

Characteristics:

  • Energy Density: Moderate to high (60-120 Wh/kg), better than NiCd.
  • Cycle Life: Moderate (500-1,000 cycles).
  • Self-Discharge Rate: High (up to 20% per month).
  • Memory Effect: Minimal, but not completely absent.
  • Environmental Impact: Less toxic than NiCd (no cadmium).
  • Applications: Consumer electronics, hybrid vehicles (e.g., Toyota Prius).
  1. Lithium-Based Batteries

There are several types of lithium-ion batteries, each with distinct properties:

3.1. Lithium-Ion (Li-ion)

  • Energy Density: High (150-250 Wh/kg).
  • Cycle Life: Moderate to high (500-1,500 cycles).
  • Self-Discharge Rate: Low (5-10% per month).
  • Memory Effect: None.
  • Applications: Smartphones, laptops, electric vehicles, and power banks.

3.2. Lithium-Polymer (LiPo)

  • Energy Density: Similar to Li-ion but allows for thinner, flexible designs.
  • Cycle Life: Moderate (300-1,000 cycles).
  • Self-Discharge Rate: Very low.
  • Memory Effect: None.
  • Applications: Drones, smartphones, wearable electronics, and RC devices.

3.3. Lithium Iron Phosphate (LiFePO4)

  • Energy Density: Moderate (90-160 Wh/kg).
  • Cycle Life: Very high (2,000-5,000 cycles).
  • Self-Discharge Rate: Very low.
  • Memory Effect: None.
  • Applications: Solar energy storage, electric vehicles, and backup power systems.

3.4. Lithium Titanate (Li4Ti5O12 or LTO)

  • Energy Density: Low (50-80 Wh/kg).
  • Cycle Life: Extremely high (up to 20,000 cycles).
  • Self-Discharge Rate: Very low.
  • Memory Effect: None.
  • Applications: Grid storage, electric buses, and military applications.
  1. Lead-Acid Batteries

Characteristics:

  • Energy Density: Low (30-50 Wh/kg).
  • Cycle Life: Low (300-500 cycles).
  • Self-Discharge Rate: Moderate (3-5% per month).
  • Memory Effect: None.
  • Environmental Impact: Contains lead and sulfuric acid, requiring careful disposal.
  • Applications: Automobiles, backup power systems (UPS), and renewable energy storage.

Internal resistances and maximum discharge currents for the various battery types

Overview of the internal resistances and maximum discharge currents for the various battery types:

  1. Nickel-Cadmium (NiCd) Batteries
  • Internal Resistance:
    • Typically low (10-20 mΩ per cell).
  • Maximum Discharge Current:
    • Very high, up to 20-50C (C = battery capacity).
    • Example: A 1,000 mAh NiCd battery can deliver up to 20-50A.
  • Notes:
    • Can handle high discharge rates without significant voltage drop.
    • Suitable for high-current applications like power tools.
  1. Nickel-Metal Hydride (NiMH) Batteries
  • Internal Resistance:
    • Moderate (20-50 mΩ per cell, higher than NiCd).
  • Maximum Discharge Current:
    • Typically 5-10C, with some high-performance cells reaching 15C.
    • Example: A 2,000 mAh NiMH battery can deliver up to 10-30A.
  • Notes:
    • Lower discharge current capability compared to NiCd, but safer and more environmentally friendly.
  1. Lithium-Based Batteries

3.1. Lithium-Ion (Li-ion)

  • Internal Resistance:
    • Low to moderate (10-30 mΩ per cell).
  • Maximum Discharge Current:
    • Typically 10-20C, with some high-performance cells reaching 30C.
    • Example: A 2,000 mAh Li-ion battery can deliver up to 20-60A.
  • Notes:
    • High energy density, but overheating risks at high discharge rates.

3.2. Lithium-Polymer (LiPo)

  • Internal Resistance:
    • Low (5-20 mΩ per cell).
  • Maximum Discharge Current:
    • Typically 20-50C, with some high-performance cells reaching 70C or more.
    • Example: A 5,000 mAh LiPo battery can deliver up to 100-350A.
  • Notes:
    • Excellent for high-current applications like drones and RC devices.

3.3. Lithium Iron Phosphate (LiFePO4)

  • Internal Resistance:
    • Moderate (10-30 mΩ per cell).
  • Maximum Discharge Current:
    • Typically 10-25C.
    • Example: A 10,000 mAh LiFePO4 battery can deliver up to 100-250A.
  • Notes:
    • Very stable and safe, even under high discharge rates.

3.4. Lithium Titanate (Li4Ti5O12 or LTO)

  • Internal Resistance:
    • Extremely low (<2 mΩ per cell).
  • Maximum Discharge Current:
    • Typically 10-30C, with some designs reaching 50C.
    • Example: A 10,000 mAh LTO battery can deliver up to 100-300A.
  • Notes:
    • Exceptional cycle life and performance, even under extreme conditions.
  1. Lead-Acid Batteries
  • Internal Resistance:
    • High compared to other chemistries (50-200 mΩ per cell, depending on type).
  • Maximum Discharge Current:
    • Typically 5-10C for starting (cranking) batteries.
    • Deep cycle batteries are limited to 1-3C.
    • Example: A 100 Ah lead-acid battery can deliver up to 100-300A (starting) or 100-200A (deep cycle).
  • Notes:
    • Not ideal for high-current applications due to voltage sag.

Charging Characteristics for different Battery Types

Charging characteristics for the battery types:

  1. Nickel-Cadmium (NiCd) Batteries
  • Charging Method:
    • Constant Current is typically used.
    • Charging is often done in two stages:
      1. Fast Charge: High current (up to 1C) until the battery reaches near full charge.
      2. Trickle Charge: Low current (0.05-0.1C) to maintain the charge.
  • Voltage Behavior During Charging:
    • Voltage rises steadily during charging, then drops slightly after reaching full charge (this is called the negative delta V characteristic).
  • Charging Time:
    • Typically 1-2 hours for fast charging.
  • Special Notes:
    • NiCd batteries are robust and tolerate overcharging well when trickle charged.
    • Avoid memory effect by fully discharging occasionally.
  1. Nickel-Metal Hydride (NiMH) Batteries
  • Charging Method:
    • Constant Current charging with careful monitoring of voltage and temperature.
    • Similar to NiCd, typically charged in two stages:
      1. Fast Charge: Up to 1C until near full charge.
      2. Trickle Charge: Low current (0.05C or less).
  • Voltage Behavior During Charging:
    • Voltage rises steadily, but the negative delta V at full charge is smaller compared to NiCd, requiring precise detection to avoid overcharging.
  • Charging Time:
    • Typically 2-4 hours for fast charging.
  • Special Notes:
    • NiMH batteries are more sensitive to overcharging and heat compared to NiCd.
    • Overcharging can reduce cycle life, so temperature monitoring is essential.
  1. Lithium-Based Batteries

3.1. Lithium-Ion (Li-ion) and Lithium-Polymer (LiPo)

  • Charging Method:
    • Charged using a Constant Current/Constant Voltage (CC/CV) method:
      1. Constant Current Phase: Battery is charged at a constant current (up to 1C).
      2. Constant Voltage Phase: When the voltage reaches the maximum level (typically 4.2V per cell), the current gradually decreases until it is minimal.
      3. Charging stops automatically when the current drops to a preset threshold.
  • Voltage Behavior During Charging:
    • Voltage rises steadily during the constant current phase and flattens during the constant voltage phase.
  • Charging Time:
    • Typically 1-4 hours, depending on the charge rate and battery capacity.
  • Special Notes:
    • Overcharging is dangerous and can lead to overheating or fire.
    • Requires a dedicated charger with precise voltage and current control.

3.2. Lithium Iron Phosphate (LiFePO4)

  • Charging Method:
    • Similar CC/CV charging method as standard lithium-ion batteries.
    • Maximum voltage is lower (typically 3.6-3.65V per cell).
  • Voltage Behavior During Charging:
    • Voltage rises steadily and flattens during the constant voltage phase.
  • Charging Time:
    • Typically 2-4 hours.
  • Special Notes:
    • Safer and more tolerant to overcharging compared to standard Li-ion batteries, but still requires a dedicated charger.

3.3. Lithium Titanate (LTO)

  • Charging Method:
    • Also uses the CC/CV method, but with a lower maximum voltage (typically 2.8V per cell).
    • Can tolerate very high charge currents due to its low internal resistance.
  • Voltage Behavior During Charging:
    • Voltage rises steadily and flattens during the constant voltage phase.
  • Charging Time:
    • Can be extremely fast (30 minutes to 1 hour) due to high charge rate capability.
  • Special Notes:
    • Extremely long cycle life and stable charging characteristics.
  1. Lead-Acid Batteries
  • Charging Method:
    • Charged using a Constant Voltage or a combination of Constant Current/Constant Voltage (CC/CV):
      1. Bulk Charge (Constant Current): Charged at a constant current until voltage reaches the set maximum (e.g., 14.4V for a 12V battery).
      2. Absorption Charge (Constant Voltage): Voltage is held constant while the current decreases gradually.
      3. Float Charge: Maintains the battery at a lower constant voltage (e.g., 13.6-13.8V for a 12V battery) to keep it fully charged.
  • Voltage Behavior During Charging:
    • Voltage rises during the bulk phase and flattens during the absorption and float phases.
  • Charging Time:
    • Typically 8-16 hours, depending on the depth of discharge and charge rate.
  • Special Notes:
    • Overcharging can cause gassing (release of hydrogen and oxygen), which reduces water levels and damages the battery.
    • Requires periodic maintenance (e.g., adding water to flooded lead-acid batteries).

Summary Table

Battery Type Charging Method Voltage Behavior Charging Time Notes
NiCd
Constant Current
Rises steadily, slight drop at full charge
1-2 hours
Tolerates overcharging; avoid memory effect.
NiMH
Constant Current
Rises steadily, small voltage drop at full charge
2-4 hours
Heat-sensitive; precise charge control needed
Li-ion / LiPo
CC/CV
Rises steadily, flattens at full charge
1-4 hours
Requires precise voltage control; overcharging is dangerous
LiFePO4
CC/CV
Rises steadily, flattens at full charge
2-4 hours
Safer than Li-ion; requires dedicated charger
LTO
CC/CV
Rises steadily, flattens at full charge
0.5-1 hour
Extremely fast charging; very durable
Lead-Acid
CC/CV or Constant Voltage
Rises steadily, flattens at float charge
8-16 hours
Overcharging causes gassing; requires maintenance

Each battery type has specific charging requirements, and using the correct charger is critical for safety, performance, and longevity!

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