What is the reason for low voltage of car battery

It may be that between the pole plates of the battery, there is a short circuit, which needs to be repaired in time.

May be the vehicle's electrolyte level is too low, the owner needs to replace or replenish the electrolyte in time.

It may be that the vehicle's battery capacity has dropped, the voltage of the battery will drop, the owner needs to replace the battery with a new one.

It may be that the wires have poor contact, resulting in abnormal voltage of the battery, the owner needs to replace the wires with new ones.

Maybe the battery has a false charge, and the drop in voltage becomes larger when discharging with high current, resulting in a lower voltage of the battery.