The common method is to use the light judgment method. The specific operation is to turn on the headlights of the car and turn on the starter while playing. In this way, we can judge the stored power of the battery at this moment by observing the dimming of the lights. In this case, it is easy to Know the discharge level of the battery.

For example, when we find that the starter rotates weakly and the light is relatively dim, it means that the battery is very discharged and needs to be charged; if it is found that the starter is running normally and the light is bright enough, then there is no need to worry too much. Because this situation shows that the voltage of the battery is stable, the technical state is relatively good, and the charging is sufficient; there is also a situation where the light is dark red after the starter is turned on, and it goes out quickly, this situation is more serious, because it implies that The battery has been seriously over-discharged or vulcanized, and should be de-vulcanized in time, and the battery needs to be replaced when necessary.