What is the current required for car ignition?
3 Answers
During gasoline engine startup, the battery output current can reach 200 to 600 amps, while for diesel engines, it can go up to 1000 amps. Below is relevant information about starting current: 1. Concept: The Cold Cranking Amps (CCA) rating refers to the minimum current obtainable under specific conditions at -17.8°C and -28.9°C. This rating connects the battery's starting capability with important variables such as engine displacement, compression ratio, temperature, starting time, the technical condition of the engine and electrical system, and the minimum operating voltage for starting and ignition. 2. Normal current value: Generally, the starting current is 20 times the operating current. If the battery is weak or not fully charged, or if the low voltage indicator is damaged, this might occur. It is recommended to test the battery voltage after 25 kilometers of driving. For a 48V battery, a reading around 50V indicates normal battery condition.
As a seasoned driver with years of experience, I find the current during ignition quite startling. At the moment of starting, the starter requires a current of 200 to 500 amps, primarily depending on the engine size and temperature conditions. The current might be slightly lower in summer and higher in winter because cold engine oil increases resistance. From my experience, small cars usually draw around 300 amps during startup, which instantly drains a significant portion of the battery's energy. If the battery is old or has been drained overnight by forgotten lights, insufficient charge can make it difficult to start the engine. I remember one winter morning when the car wouldn't start at all—after checking, the current exceeded 400 amps, and it turned out the battery was leaking and had corroded the terminals. That’s why it’s crucial to regularly inspect the battery and starting system, rather than regretting it when stranded on the road. The current for spark plug ignition is much smaller, but it’s still part of the system.
From a mechanical perspective, the ignition current is primarily divided into two parts: starter motor consumption and ignition system consumption. At the moment of starting, that large motor has to swallow hundreds of amps to rotate the flywheel. I've measured some vehicles - regular sedans draw around 300 amps, while SUVs or trucks can exceed 500 amps. This entirely relies on the battery's instantaneous power output, reflected by its CCA (cold cranking amps) rating. The ignition coil's high-voltage conversion for spark plug firing is a low-current task, perhaps just a few amps, but high voltage is crucial. Overall, if cables are thin or connections are loose, increased resistance leads to insufficient current, making starting difficult. When helping friends repair cars, I've found that keeping batteries clean and terminals tight prevents many issues, especially during humid rainy seasons. Using a voltmeter to check starting voltage can help diagnose problems earlier.
