At what voltage does a car battery fail to start the engine?
2 Answers
When the open-circuit voltage of a car battery drops below 12.2V and the load voltage falls under 9.5V, the vehicle will be difficult to start. Car owners should regularly inspect their car batteries by checking the observation window on the battery. If the window displays black, it indicates the need for charging; green signifies good condition, while white suggests insufficient electrolyte. Precautions for car battery usage: 1. Monitor battery lifespan: If a car battery has been in use for over 3 to 4 years, it should be replaced. Prolonged use diminishes its charge storage capacity, necessitating timely replacement. An overused battery may experience power depletion, preventing the vehicle from starting and disrupting normal use. 2. For vehicles left unused for extended periods: Fully charge the battery beforehand and start the vehicle once a month, then drive at moderate speed for a while to recharge the battery. Long-term storage may lead to battery depletion; if possible, remove and store the battery in a well-ventilated area with moderate temperature. 3. Time control: Limit each engine start attempt to 3-5 seconds to avoid damaging the battery. If the vehicle fails to start after several attempts, inspect the ignition system instead of repeatedly trying to start the engine.
I've experienced a dead battery several times and noticed that if the voltage drops below 12 volts before starting, the car struggles to ignite. If it falls below 11.5 volts, it basically refuses to start altogether. Once, I measured it at 11.3 volts, and no matter how much I turned the key, all I heard was a clicking sound. I recommend keeping a car charger with a voltage display handy, plugging it into the cigarette lighter to monitor the voltage. When the engine is off, a voltage around 12.2 volts is reassuring. The problem becomes more pronounced in cold weather; at temperatures below -10 degrees Celsius, the voltage drops particularly fast, so it's best to park in an underground garage. Additionally, if the battery is over three years old, you need to be extra cautious. Once, my old battery showed 12 volts, but the moment I tried to start the car, it plummeted to 8 volts, and I ended up needing a rescue service to replace it with a new one.
