Which battery is primarily used for engine start power?

The starter battery is specifically designed to provide the necessary power for engine starts. It is built to deliver high bursts of current required to crank the engine, which is typically much higher than what other batteries in the system can handle efficiently. This battery is engineered with properties that enable it to quickly provide significant power for short durations, essential for the starting process.

Using batteries primarily designed for other functions, such as auxiliary or main batteries, would not be ideal for engine starting due to their specifications that are geared more toward maintaining steady power output for extended periods rather than providing short, powerful surges. This makes the starter battery the correct choice for engine start applications.