Why should the battery negative pole on the car be grounded? Can't it be grounded without it?

The reason why the negative electrode is grounded is because the automobile electrical appliances use direct current, and adopt series, parallel or series-parallel-series circuits, all of which have positive and negative electrodes. The loop of the load should be directly connected to the negative electrode of the battery through wires. If discrete wiring is adopted, there will be hundreds of wires on the battery.

In order to save wire materials and facilitate installation, the general automobile circuit adopts single-wire system, that is, the positive wire of the battery is directly connected with all electrical equipment, the negative wire of the battery is directly connected with the metal part of the frame, and the negative wire of the electrical equipment is also connected with the nearby metal part of the frame, and the metal body of the engine and the automobile chassis (beam frame) is used as a public channel. This way of connecting the negative wire with the car body is called grounding.

The negative electrode of the battery is grounded for the normal use of vehicle electrical appliances. The positive pole of the vehicle electrical appliance is connected to the positive pole of the battery and the negative pole is placed on the vehicle body. If your battery is not grounded, the vehicle-mounted electrical appliances cannot form a complete circuit and cannot be used.

Negative grounding has the advantages of less interference to electronic devices, less electrochemical corrosion to frame and car body, and firm connection. At present, most cars are grounded at the negative pole. Generally, there are more than two main grounding wires on the car, one is the negative battery wire, and the other is the grounding wire between the engine and the girder. For the sake of safety, there are also grounding wires between the transmission and the big beam, and between the metal shell of the carriage and the big beam.

Poor grounding will cause many obvious or hidden faults in the circuit. In the ignition system, if the engine is poorly grounded, the spark of the spark plug will be weak and the power of the car will be weakened. In modern cars, poor grounding can also cause damage to the ignition electronic module. In the starting circuit, if the engine is poorly grounded, the speed of the starter will slow down and the armature will heat up, which will easily burn the starter after a long time.

Extended information: brief introduction of automobile battery;

1. Battery is an indispensable part of automobile, which can be divided into traditional lead-acid battery and maintenance-free battery. Because the lead-calcium alloy is used as the grid frame of the battery, the decomposition amount of water generated during charging is low and the evaporation of water is low. In addition, the shell adopts a sealed structure, and little sulfuric acid gas is released. Therefore, compared with the traditional battery, it has the advantages of no need to add any liquid and long storage time of the wiring pile.

2. If the battery is not used for a long time, it will slowly discharge itself until it is scrapped. Therefore, the car should start regularly to charge the battery. Another method is to unplug the two electrodes on the battery. It should be noted that the positive and negative electrode wires should be removed from the electrode post, and the negative electrode wire should be removed first, or the connection between the negative electrode and the automobile chassis should be removed.

3. Then unplug the plus sign (+) at the other end. The battery has a certain service life and will be replaced in a certain period. The same sequence should be followed when replacing, but when connecting the electrode wires, the sequence is just the opposite, first connecting the positive electrode and then connecting the negative electrode.

4. When the ammeter pointer shows that the storage capacity is insufficient, it should be charged in time. The storage capacity of the battery can be reflected on the dashboard. Sometimes on the way, I find that there is not enough power to start the engine. As a temporary measure, you can ask other vehicles for help, start the vehicle with their batteries, and connect the negative electrodes of the two batteries to the negative electrodes and the positive electrodes to the positive electrodes.

5. The density of electrolyte should be adjusted according to the standards of different regions and seasons. When the electrolyte is insufficient, distilled water or special rehydration should be added. Never drink pure water instead. Because pure water contains a variety of trace elements, it will have adverse effects on batteries.

6. When the car is started, due to the continuous use of the starter, the battery is damaged due to excessive discharge. The correct way to use it is that the total time of starting the car at one time should not exceed 5 seconds, and the interval of starting it again should not be less than 15 seconds. If the car still doesn't start for many times, we should find the reason from other aspects such as circuit, ignition coil or oil circuit.

7. In daily driving, always check whether the hole on the battery cover is ventilated. If the hole in the battery cover is blocked, the generated hydrogen and oxygen can't be discharged, and the expansion of electrolyte will make the battery shell burst, which will affect the battery life. Check the anode and cathode of the battery for signs of oxidation. You can water the battery wire connector with hot water at any time.

Reference: Baidu Encyclopedia Automobile Battery