What should the charging current be set to for a car battery?
2 Answers
For a car battery, the charging current should be set between 4 to 5 amps. Typically, a small car battery is 12v45AH, and it takes about 10 hours to fully charge with a 4.5 amp current, or about 9 hours with a 5 amp current. Among the performance parameters of a car battery, there is a CCA parameter, which stands for the battery's maximum discharge current value. When charging the battery, the charging current must never exceed the CCA current value, as forcing a higher current will damage the battery. The smaller the charging current, the longer the battery's lifespan, because a higher charging current leads to more intense chemical reactions inside the battery, which directly affects its lifespan. When the battery is not in use, it should be charged once a month to extend its service life.
I've been driving various small cars for nearly twenty years, and based on my experience, setting the charging current to around 10% of the battery capacity is most appropriate. For example, my car's battery is 60 ampere-hours, so I set the current to 6 amps. This slow charging rate protects the battery. If the current is too high, say above 20 amps, it can easily burn out the electrodes or shorten the battery's lifespan. On the other hand, if it's too low, the charging process takes too long. Typically, charging takes about seven to eight hours, and don't forget to ensure good ventilation to avoid heat buildup. I also frequently check if the battery terminals are clean to ensure smooth current flow. If the battery frequently runs out of power, it's essential to check if the alternator is faulty instead of relying solely on charging. Using a simple voltmeter to monitor the charging process and stopping once the battery is full saves electricity and ensures safety. In summary, adjusting the current based on a percentage of the capacity is both safe and efficient.
