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The battery is the core part of the automotive electrical system, which can not only provide energy when the vehicle is started, but also power the electrical equipment of the entire vehicle. The service life of a car battery is generally 3 years, but the specific situation still depends on the owner's driving habits. There are also cases where the battery loses power in less than a year of a new car, which is also closely related to driving habits.
In this article, signs of a bad battery is mainly discussed in order to keep electric vehicles and its batteries healthy.
Signs of a bad battery
Do you know the premonitory signs of car battery failure? When a car encounters the following situations, one must be vigilant.
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Difficulty starting the car
When there are no other factors, if the car suddenly experiences difficulty starting, it may be a sign of a bad battery, which is a precursor to the imminent failure of the battery. But if it's winter, it may be the so-called cold start difficulty.
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Dim lights when the car is idling
When waiting for a red light or temporary parking, the headlights of your car suddenly dim. This is a typical sign of a bad battery, as the charging power of the engine decreases during idle. If the battery is almost unusable at this time and other devices in the car need to be powered, the headlights will consume a large amount of electricity, resulting in insufficient power supply and dimming of the lights.
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The battery fault light is on
The malfunction light is the most directly visible one of the signs of a bad battery, and it should be sent for inspection immediately, otherwise it would be too troublesome for the car to get stuck halfway! Kind reminder: It is necessary to maintain the battery regularly and do a good job of battery maintenance in a timely manner!
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Abnormal noise occurs during startup
Due to the weakened discharge capacity of the battery, the starter motor may malfunction and make a squeaking sound, which is the most common one of the signs of a bad battery at low temperatures. Because the weather is cold, the activity of the battery will also decrease, but it will improve or disappear after the weather warms up, so many car owners do not take it seriously.
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Check the battery observation hole
There is an observation hole on maintenance free batteries, and the light on the observation hole displays whether the battery is working properly. Green indicates good, and black indicates that the battery needs to be replaced. This is the most obvious one of the signs of a bad battery However, some car owners may also report that this light is not very reliable. Even if it is green, it cannot start the car. Let's use the observation hole as a simple reference.
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The surface of the battery bulges and leaks
This is the most dangerous sign of a bad battery. If the battery is found to be bulging or leaking, it means that the car has a safety hazard and must be replaced in a timely manner.
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Observe the starting voltage of the battery
The normal working voltage of the battery is about 12V. When the vehicle starts the generator for charging, the voltage will rise to around 13-14V. Many cars have a voltage check function, which pays attention to the voltage changes before and after starting to distinguish whether the battery is good or bad.
If the vehicle is already below 12V before starting or below 13V after starting, it may be a power supply problem with the battery.
Normally, the lifespan of a battery is around 2-3 years. But due to individual differences in usage, this is not absolute. This requires car owners to regularly check and understand the condition of the vehicle. Once a problem is found with the battery, promptly repair or replace it according to suggestions.
Causes of a bad battery
After knowing signs of a bad battery, it’s better to know the causes of a bad battery and avoid the bad using habits.
For car batteries, the optimal operating temperature is 25 ° C. Data shows that for every 1 ° C decrease in temperature, the available capacity of the battery will decrease by approximately 0.8%, and temperature will affect the battery's lifespan. In addition, factors such as driving habits and frequency can also affect driving habits.
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Battery aging or damage
The service life of car batteries is usually 3-5 years. As the usage time increases, the chemical substances inside the battery will gradually become ineffective, resulting in a decrease in battery capacity and inability to supply power normally. In addition, the fuses or relays related to the battery are damaged, causing the battery to be unable to supply power normally.
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Charging system malfunction
The generator or voltage regulator has malfunctioned, causing the battery to not charge properly.
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Circuit connection issues
Loose, corroded, or poorly connected battery terminals result in the inability to transmit current properly.
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Excessive electrical load
Too many electronic devices are installed on the vehicle, resulting in excessive battery load, which can lead to signs of a bad battery in the long run.
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Long term parking of vehicles
If the vehicle is parked for a long time without use, the battery will naturally discharge, resulting in insufficient power.
How to check the battery condition
For professionals, here are few methods of checking battery condition and diagnose the signs of a bad battery.
Power battery system faults can be classified into three categories based on the location of the fault, namely single battery faults, battery management system faults, and circuit or connector faults.
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Single battery faults
There are three types of faults in a single battery.
The first type of faulty battery has normal performance and does not need to be replaced. The corresponding faults include low indivisual batteries SOC and high SOC of individual batteries. If the SOC of a single battery is low, the voltage of the battery will first reach the discharge cut-off voltage during the driving process of the car, resulting in a decrease in the actual battery capacity. Therefore, the single battery should be recharged. If the SOC of a single battery is too high, the battery will reach the charging cut-off voltage first at the end of charging, which will affect the charging capacity and require separate supplementary discharge of the single battery.
The second type of fault battery has severe performance degradation and should be replaced immediately. The corresponding faults include insufficient capacity and high internal resistance of individual batteries. If the internal resistance of lithium-ion batteries is too high, it will seriously affect the electrochemical performance of the battery, such as severe polarization during charging and discharging, low utilization of active materials, and poor cycling performance.
The third type of faulty battery affects driving safety, and the corresponding faults include internal short circuits in individual batteries; External short circuit of individual battery cells; The polarity of a single battery is reversed, and under strong vibration, the active materials, terminals, external connections, and solder joints on the electrode ears and plates of lithium-ion batteries may break or detach, causing internal or external short circuits in the single battery.
In general, the causes of the first two types of failures in individual batteries may include two factors: one is the consistency issue of individual batteries when grouping power batteries, where there are differences in SOC, capacity, and internal resistance of individual batteries; The second issue is the increase in consistency differences caused by differences in the application environment (such as temperature, charge and discharge current) during the group application of individual batteries, which exacerbates the inconsistency of individual batteries.
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Battery management system faults
The battery management system plays an important role in ensuring the safety and service life of the battery pack, and maximizing the efficiency of the battery system. The battery management system usually monitors and samples the individual voltage, total voltage, total current, and temperature in real time, and feeds back the real-time parameters to the vehicle controller. In addition to monitoring battery performance parameters and implementing electrical performance management, the battery management system also has thermal management as the main application environment management, implementing heating and cooling of the battery to ensure good application environment temperature and temperature field consistency of the battery.
Battery management system failures include CAN communication failures, total voltage measurement failures, individual voltage measurement failures, temperature measurement failures, current measurement failures, relay failures, heater failures, and cooling system failures.
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Circuit or connector faults
The diagnosis of faults in circuits or connectors is equally important for ensuring driving safety and the reliability of the entire vehicle. For example, due to the vibration of the vehicle, the connecting bolts between the batteries may loosen, the contact resistance between the batteries may increase, and virtual connection faults may occur between the batteries, resulting in increased energy loss inside the battery pack, causing insufficient power and short driving range of the vehicle. In extreme cases, it can also cause high temperatures, generate arcs, melt battery electrodes and connecting pieces, and even cause extreme battery safety accidents such as battery fires.
During the operation of electric vehicles, relative jumping may occur between individual batteries, causing the connecting pieces between the two batteries to break. The electrical connection between the battery box and electric vehicles is also a high incidence point of faults. After prolonged vibration, the electrical connectors are prone to virtual connections, which can cause problems such as burning and poor contact.
Maintenance tips for electric vehicles’ batteries
The following is the tips for maintaining the EV batteries health and extending the service time for your electirc vehicles.
Maintain a suitable charging state
Try to keep the battery level within a reasonable range, such as 20% -80%, to extend battery life.
Avoid overcharging and overdischarging
Monitor battery level to avoid prolonged charging after reaching 100%, and to avoid discharging to extremely low levels.
Regularly fully charge and discharge
Regularly conduct a full charge discharge cycle to assist in battery calibration and maintain its capacity.
Fast and slow combination charging
Although fast charging is convenient, frequent use may affect battery health, so it should be combined with slow charging appropriately.
Moderate long-term storage capacity
If the vehicle is not planned to be used for a long time, the battery should be charged to a moderate level (such as 50% -60%) and stored, and the battery status should be checked regularly. It should be charged at least once a month.
Avoid high temperature charging
High temperature environment has a negative impact on the lifespan of batteries especially lithium ion battery life. During high temperature seasons such as summer, it is advisable to choose a charging location that avoids direct sunlight. Before charging, turn off the vehicle for 10 minutes to allow the battery temperature to naturally decrease before starting the charging process.
Precautions for Charging
Avoid using high-power vehicle equipment such as air conditioning while charging.
Charging environment
Charge in a well ventilated, dry, and non direct sunlight environment to avoid extreme temperature conditions.
Use protective facilities
Use charging equipment with overcharge, overdischarge, and short circuit protection functions.
When to replace the electric vehicles’ batteries
There are mainly two types of power batteries used in new energy vehicles, one is lithium iron phosphate batteries, and the other is NCM batteries.
The charging cycle of lithium iron phosphate battery is 3000-7000 times. Based on the BYD Tang DM pure electric driving range of 80 kilometers, the battery can be used for 240,000-560,000 kilometers.
The cycle number of NCM batteries is relatively low, only 1000-3000times, but it excels in its high energy density, which can make the driving range of new energy vehicles longer. Theoretically, taking the BYD yuan EV300 equipped with a NCM battery as an example, if fully charged once, it can travel 300 kilometers. Therefore, the ternary lithium battery can enable the vehicle to travel 300,000~900,000 kilometers. The actual service life of NCM batteries is greatly affected by the decay rate, and the capacity usually decreases rapidly after 1500-2000 cycles, so the actual life may be lower than the theoretical value.
Generally speaking, household cars typically travel less than 20000 kilometers per year, with few exceeding 20000 kilometers per year. If the battery life drops sharply or signs of a bad battery occur frequently, replacement should be considered.
Conclusion
The health status of car batteries directly affects the normal use and driving safety of vehicles. Signs of a bad battery is essential warning for you to know more about the health of your vehicles ensuring the long lifespan. By understanding the precursors of battery failure in this article lithium battery failure, common causes of faults, and correct maintenance methods, car owners can better grasp the battery status, promptly detect problems, and take corresponding measures.
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