At what voltage can the battery not start?
3 Answers
The battery cannot start when the voltage is below 12 volts. The load voltage should be greater than 11 volts, generally between 12V and 16V. After the car starts, the generator begins to generate electricity. For 12V vehicle systems, the battery voltage should be between 13.5 and 14.5 volts, while for 24V vehicle systems, it should be maintained between 27 and 29 volts. The quality of the battery depends on its capacity, which can be measured with a capacity meter. For example, if the battery voltage is sufficient but it runs out of power after a few ignition attempts, the battery is likely faulty. Common gasoline engine cars typically use a 12V battery, while multi-cylinder diesel engines and single-cylinder diesel engines with more than 25 horsepower usually adopt a 24V battery voltage supply.
I've driven for many years and remember that a car battery's normal voltage should be around 12.6V. When it drops below 12V, starting problems may occur. Especially in winter when the engine is cold, the starter requires high current, and if the voltage falls below 11.8V, it usually won't start. Once my battery showed 11.9V, and after several attempts, it still wouldn't start, forcing me to call a tow truck. I recommend developing a habit of using a simple voltmeter to check regularly—plugging one into the cigarette lighter is very convenient. As the battery ages, the voltage drops more easily, so pay attention to its lifespan of 3-5 years. Batteries self-discharge when parked for long periods, so don't leave the car unused for more than half a month. Starting it periodically to recharge can help prevent issues.
As someone who frequently works on cars, I get nervous when my battery voltage drops below 12V. A fully charged battery normally reads 12.6V, but starting becomes difficult when it's below 12V, especially in sub-zero temperatures. Through several tests, I've found that it absolutely won't start below 11.7V, so I keep a portable jump starter in my car for emergencies. Checking voltage is easy—just buy a multimeter online for a few dozen bucks and measure it. As batteries age, their voltage drops faster. You should be alert when it's below 12.2V and charge or replace it promptly. Don't wait until it dies—checking the voltage monthly is the safest approach.
