What current should be set when charging a car battery?
2 Answers
When charging a car battery, the charging current should be determined based on the battery's capacity. Generally, car batteries range from 36AH (smallest) to 80AH (largest) for passenger vehicles (truck batteries are even larger). The charging current is typically set between 0.1C to 0.2C (where C is the capacity value). For a 36AH battery, a charging current of 4A to 8A is appropriate, while an 80AH battery requires 8A to 16A. Under normal conditions, a charger can fully charge the battery in 4 to 5 hours. Avoid frequently overcharging the battery. Although the current generated by the charger is not high, prolonged boiling of the electrolyte can cause fine particles on the surface to detach, potentially leading to oxidation and loosening of the active material from the grid framework.
When it comes to adjusting the current for car battery charging, I believe the safest approach is to first check the battery's capacity label, usually marked in ampere-hours (Ah). For example, a 60Ah battery would ideally be charged at around 6A, roughly one-tenth of its capacity. Avoid setting the current too high, as excessive current may overheat and damage the battery—I once tried charging at 10A and ended up swelling the battery, which was a hassle to fix. Slow charging at a lower current, like 2A, may take several hours to reach full charge, but it's gentler on the battery and can even extend its lifespan. I recommend using a smart charger that automatically controls the current for convenience. Before starting, always turn off the engine to ensure safety and prevent sparks from electrical leaks. In short, take it slow and steady.
