At what battery voltage will the car fail to start?
3 Answers
When the open-circuit voltage of the battery is below 12.2V and the load voltage is below 9.5V, the car will fail to start. Methods to extend battery life include: 1. Avoid parking the car in open parking lots for extended periods to prevent battery freezing damage; 2. In winter, when the car engine is hard to start, each attempt should not exceed 5 seconds; 3. Charge the battery regularly by starting the car periodically; 4. Clean the battery terminals periodically and apply specialized grease to protect the wiring; 5. Avoid using car electronics after turning off the engine, as using the battery alone without the engine generating power can cause damage.
Generally, when a car battery voltage drops below 12.0 volts, it becomes difficult to start the engine. A fully charged battery should read around 12.6 volts. Having repaired cars for many years, I've encountered numerous cases where the voltage drops to 11.8 volts, almost certainly resulting in a failed start, especially in cold weather. The usual causes are battery aging or prolonged inactivity, leading to insufficient power that makes the starter motor too weak. If the voltage falls below 10 volts, there's virtually no hope of starting the car, and you'll need a jump start or towing service. It's advisable to regularly check the voltage with a multimeter and recharge the battery if it drops below 12.4 volts to avoid trouble. Additionally, a car battery typically lasts 3 to 5 years. Even if the voltage seems normal when the battery ages, increased internal resistance can still prevent the engine from starting, so comprehensive checks and timely replacement are necessary.
That winter morning, the car just wouldn't start, and the voltage measured only 11.5 volts! After checking, my friend told me that problems are likely to occur when the voltage drops below 12.0 volts, and normal starting requires at least 12.6 volts. When the voltage falls below 12.0 volts, insufficient current prevents the engine from turning over, and the cold temperature further reduces the battery's performance. Now I've developed a habit of regularly checking the voltage display on the cigarette lighter. If it's below 12.4 volts, I charge it to avoid delays like that time when I was late for work. Poor battery maintenance or forgetting to turn off electrical devices can lead to rapid discharge. Paying attention in advance can save a lot of trouble. If you encounter low voltage, don't force it, as it might damage the starter.
