How long does it take to charge a car battery at idle after a jump start?
1 Answers
It takes 10 to 15 hours to charge a dead car battery at idle. Here are specific methods to determine whether charging at idle is possible: 1. Voltage assessment: First, the voltage is absolutely sufficient. According to national standards, the voltage requirement for a 12-volt system alternator is constant at 14.5V±0.25V, meaning the alternator output voltage remains unchanged whether at idle or at maximum RPM. This clearly indicates sufficient voltage for charging. 2. Current assessment: The ideal charging current for a standard lead-acid battery is 1/10 of its capacity. Taking the most common 65AH battery as an example, its ideal charging current is 6.5 amps. From the national standards for alternator output current requirements, even the lowest-power alternator has a minimum output current of 16A, far exceeding the charging requirements.