Electric vehicles generally use maintenance-free lead-acid batteries with colloidal electrolytes, which are divided into 24V, 36V, 48V and 60V. 36V and 48V are more, and 24V and 60V are less on the market. 24V is two, 36V is three, 48V is four and 60V is five 12V single batteries in series; every single battery is 12V and consists of 6 compartments. Each battery is 12 V and consists of 6 cases in series, each with 2 V, each with positive and negative electrode plates and colloidal electrolytes. The reasons for battery damage are complex and are divided into 6 types.

1, "overcharge" causes battery damage.

　　"Overcharge" is an overcharge to the battery and the battery's chemical and physical properties of a destructive phenomenon.

　　"Overcharge" is, first of all, the reason for the charger. The current electric car charger has a safe charging voltage setting. The charging voltage is generally set within 1.2 times the standard voltage of the battery, such as a 48V battery. The charging voltage is set to 57.2V. When the battery is discharged, the voltage will gradually drop. When charging the battery again, the red light of the charger will light up, indicating that charging is in progress. When the electricity is continuously input to the battery, the voltage will rise until it is close to or equal to the charging voltage when the green light of the charger will light up. At this time, charging stops or trickle charging. If the charger voltage components fail, charging will not stop, the charging current will be uninterruptedly input to the battery, the voltage will keep rising, the result of the voltage rise will intensify the thermal reaction of the electrolyte, and the light battery shell will be deformed (expansion), the heavy battery is caused by the charge burst.

　　Secondly, because of the imbalance between the battery voltage caused by "overcharge",. As mentioned above, the battery group is composed of 2-5 12V batteries. When the battery is first shipped, the voltage of each battery is very close to the group, but after use for a period of time, the voltage between the batteries will be different from the so-called "pressure difference". The electric car charger is charging the battery group in series at the same time, the battery with higher voltage will be fully charged first, and the battery with lower voltage will be fully charged after or even in charging all the time because the charger is set with the overall voltage for charging or stop charging. Therefore, the battery which is fully charged first will be in an "overcharge" state. When the "pressure difference" is small, it does not affect the battery much, but when the "pressure difference" is large, the battery that is often "overcharged" will produce an increased thermal reaction of the electrolyte until the battery is badly charged.

　　2, "water loss" makes the battery bad.

　　"Water loss" is one of the basic reasons for the reduction of battery capacity. Most electric vehicles are maintenance-free lead-acid batteries, and many users will say this battery is sealed and maintenance-free. Why there is still a "water loss" phenomenon? The reason is very simple, water is an important component participating in the battery electrolysis reaction. Once the battery overcharge, high current discharge, internal resistance, short circuit, etc., easy to generate heat and the formation of water vapour, water vapor in the sealed battery box will be mostly retained, but also a very small part will be lost (due to the density of the battery shell material), over time, the battery will appear "Water loss" state. Generally speaking, the electric car battery will have a "water loss" state for more than 6 months. The higher the motor power, the more serious the "water loss" state.

　　3, "power loss" leads to battery damage.

　　The "power loss" is a phenomenon of battery power shortage, low voltage when the forced over-discharge is generated by the destruction of the battery plate coating. You know, any car electrical appliances have a standard range of working voltage, more than this range of electrical appliances are easy to short circuit or even burn, below this range of electrical appliances can not start or work properly, and even affect the life of the car electrical appliances and batteries are such. Many users in the use of electric vehicles is often a few days charging once, and some daily trip more than 60% of the nominal mileage of the new battery, know the battery capacity decline will lead to insufficient battery voltage (Undervoltage), insufficient voltage can not effectively meet the basic voltage supply of the car appliances, when the voltage drops, the user is still using the electric vehicle, and the battery can not provide normal voltage, so it will be due to the load of the car; therefore, the load of the electric appliance will make the battery under-voltage "power loss", and the regular "power loss" will make the battery plate lead layer gradually peel off, until the plate is damaged.

　　4、Sulfuration of the pole plate leads to battery damage.

　　What is battery sulphide? In the pole, the plate generates white hard lead sulphate crystals, charging and very difficult to convert into active material of lead sulphate. This is sulfation, referred to as "sulphide". The reason for this kind of lead sulphate is that when the lead sulphate particles are dissolved in the electrolyte and saturated after over-discharging or discharging for a long time, the lead sulphate recrystallizes when the temperature is low, and the crystalline lead sulphate is precipitated. This grows and develops again and again on the once precipitated particles due to temperature changes, making the crystalline particles increase. This kind of lead sulphate has poor electrical conductivity and high resistance, and its solubility and dissolution rate are small, so it is difficult to recover when charging. Thus, it becomes the cause of capacity reduction and life-shortening. Sulfidation is the main crux of the battery capacity reduction, but the current severe damage to the battery plate is a more significant crux of the electric car battery capacity reduction.

　　5, start, acceleration, and overload are generated by the high current discharge so that the battery is damaged.

　　The instantaneous current of an electric car starting and accelerating is very large, generally reaching 20A-50A. According to the size of electric car motor power, the normal discharge current is generally controlled within 10A. Because the instantaneous current is too large, the electrolytic reaction increases sharply, the pole plate coating is bound to be affected to a certain extent, and over time the pole plate lead layer powder will gradually fall off due to the instantaneous high current pull, the electrolyte will be black (due to lead powder), and the battery will be scrapped. Overload is the electric car driving load overweight, such as excessive load, carrying people, the overload will make the battery discharge load increased, a long time of high current discharge, will directly affect the plate coating, accelerate the process of softening the plate. There is also the bad road conditions will also make the electric car flat and heavy braking and starting, such as potholes, red lights, roadblocks and so on. These are all factors that cause high current discharge. It is also worth mentioning that the greater the electric car motor power, the shorter the life of its battery. This is because the more significant the motor power, the greater the discharge current, and the greater the damage to the battery.