Lithium batteries offer numerous advantages, including their high energy density, long cycle life, fast charging capability, and environmental friendliness, making them an attractive choice for a wide range of applications, from consumer electronics to electric vehicles and renewable energy storage systems. While lithium batteries have gained prominence for their versatility and efficiency, they are not typically recommended for use as start batteries in vehicles.

1. Requirements of a start battery

Let’s delve into the start batteries first, they also known as starting batteries or cranking batteries, are specifically designed to provide high bursts of power for short durations, primarily to start the engine of a vehicle. These batteries have distinct requirements to effectively perform this function. Here are the key requirements of a start battery:

1.1  High Cranking Amps (CA) and Cold Cranking Amps (CCA)

• Start batteries are essential for engine starting, requiring high cranking amps to deliver the necessary power. During startup, the starter motor faces resistance from engine components and air-fuel compression, demanding significant torque proportional to the current flow. This torque overcomes resistance and initiates the engine cranking process. A burst of electrical power, typically measured in Cold Cranking Amps (CCA), is crucial for swiftly turning the engine and igniting combustion. This surge of energy, provided by the start battery, ensures reliable engine startup, making high current output imperative for efficient performance.

1.2  High Voltage Stability

• Maintaining a stable voltage output from start batteries is crucial for consistent and reliable engine startup, as it prevents drops that could lead to starting issues or damage to electrical components. Fluctuations in voltage can reduce cranking speed, potentially causing engine startup failures. The starter motor operates most efficiently within a specific voltage range, ensuring effective performance and longevity. Additionally, other vehicle components, such as the ignition system and engine control unit (ECU), rely on a stable voltage supply to function properly. Voltage spikes or drops during engine cranking can damage sensitive electronic components, highlighting the importance of stable voltage output from start batteries.

1.3  Low Internal Resistance

• Start batteries should have low internal resistance to facilitate the rapid discharge of energy needed for engine cranking. Low internal resistance allows for efficient power transfer from the battery to the starter motor, minimizing voltage drop and maximizing cranking performance.

1.4  Fast Recharge Rate

• After engine startup, start batteries need to quickly recharge to replenish the energy used during cranking. A fast recharge rate ensures that the battery is ready for the next engine start and can support the vehicle's electrical systems while driving.

1.5  Durability and Vibration Resistance

• Start batteries are often subjected to vibrations and harsh conditions, especially in automotive applications. Therefore, they need to be durable and resistant to vibration to withstand the rigors of vehicle operation without compromising performance or longevity.

1.6  Compatibility with Vehicle Charging System

• Start batteries should be compatible with the vehicle's charging system to ensure proper charging and optimal performance. Compatibility includes voltage regulation and charging algorithms tailored to the battery's chemistry and characteristics.

2. Why lithium batteries not be used as starting battery?

Now we can easily see why lithium batteries cannot be used as a start battery, here are the reasons:

2.1  Current Output Limitations

• Lithium batteries have lower internal resistance compared to lead-acid batteries, allowing them to deliver power more efficiently over longer periods. However, this lower internal resistance also means that they struggle to provide the extremely high currents required for engine cranking.

2.2  Voltage Stability

• Lithium batteries have a different voltage discharge curve compared to traditional lead-acid batteries commonly used in vehicles. Lead-acid batteries provide a relatively stable voltage output, which is crucial for starting the engine consistently. In contrast, the voltage of lithium batteries decreases more rapidly as they discharge, which can result in inconsistent starting performance.

2.3  Cold Weather Performance

• Lead-acid batteries perform better in cold weather conditions compared to lithium batteries. Starting a vehicle in cold temperatures requires a high burst of energy, and lead-acid batteries are better suited to deliver this energy reliably under such conditions.

2.4  Compatibility

• Vehicle charging systems are typically designed for lead-acid batteries, which require specific voltage levels for proper charging. Using a lithium battery without the appropriate charging system can lead to overcharging or undercharging, potentially damaging the battery and other electrical components of the vehicle.

Conclusion

While lithium batteries offer advantages such as lighter weight and higher energy density, they are better suited for applications where their unique characteristics can be properly managed and optimized, such as in electric vehicles or as auxiliary power sources rather than as starter batteries in traditional internal combustion engine vehicles.

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