402030 battery

Why do we need to balance the 402030 battery?

The practical problem of a long service life for a single battery and a short service life for a group has been around for a long time and has always been a lingering criticism of the majority of users. The main manifestations in use are:

First, the output power drops significantly. For the same load, especially the power load, the power performance drops rapidly and the full power operation time is significantly shortened.

Second, the capacity is greatly reduced. The effective discharge time is very short, and the discharge is quickly prompted to be over, and the actual discharge capacity is seriously reduced; when charging, it is quickly displayed as fully charged, and the actual charging time is greatly reduced.

Third, the heat is severe during charging and discharging. Batteries with severe heat generation are mainly concentrated on batteries with severe capacity attenuation, and the temperature of the surrounding batteries rises rapidly through heat transfer. The temperature of batteries with severe capacity attenuation is the highest mainly because the internal resistance of this type of battery is the largest, and the heat generated under the action of a larger current is the most. When too much heat accumulates in a short period of time and cannot be effectively controlled, thermal runaway is very likely to occur, causing battery explosions and fire accidents.

Fourth, the endurance time and mileage are greatly reduced. Under the condition of constant load, the endurance time and mileage will be greatly reduced in a very short time, which is most obvious in electric vehicles, and the corresponding charging capacity will also be greatly reduced.

Actual test data show that when the 402030 battery has obvious consistency differences, the technical parameter differences of the battery are most obvious, mainly reflected in the differences in parameters such as voltage, internal resistance, capacity, self-discharge rate, and discharge curve.

With the help of testing instruments, it can be found that the voltage consistency of such 402030 batterys is the worst. Whether during charging or discharging, the voltage difference is usually large, especially in the middle and late stages of charging and discharging. For this kind of 402030 battery, the actual charge and discharge capacity depends on the battery with the smallest capacity and the most severe attenuation, and has nothing to do with the capacity of other batteries. Even if the capacity of other batteries is more, it will not play any role. The more 402030 batterys are in series, the more serious the capacity waste problem is.

The consistency problem will cause small-capacity batteries to frequently overcharge and over-discharge. Each overcharge and over-discharge will cause irreversible damage to the battery. The more times the overcharge and discharge occur, the more serious the damage. Solving the consistency problem will also solve the problem of battery overcharge and over-discharge. The next benefits are improved capacity utilization, controlled thermal runaway risks, and relatively stable capacity.

The biggest risk during the use of batteries is thermal runaway. Once thermal runaway occurs, it is easy to cause battery explosion and fire accidents. To prevent thermal runaway, it is relatively easy to manage single power supply equipment. After eliminating the problem of battery production quality, a qualified voltage control system can easily solve it; but for 402030 batterys, it is much more difficult. The voltage control system used by the unit battery is almost ineffective on the 402030 battery. The more strings of 402030 batterys, the more difficult it is to manage. A dedicated battery balancing management system must be developed.

At present, common battery balancing technologies mainly include energy-consuming passive balancing, charging balancing, and transfer active balancing. In terms of development difficulty, cost, balancing efficiency, and power utilization, passive balancing is the easiest to develop and the lowest cost. The balancing current is very small, usually within 100 mA, the balancing efficiency is low, and the power utilization rate is zero; charging balancing is relatively complex, and the cost is much higher. The balancing current can reach the ampere level, and the balancing efficiency and power utilization rate are high; transfer active balancing is more complex and has the highest cost. The maximum balancing current can reach more than several amperes, and the balancing efficiency and power utilization rate are the highest.

In terms of application effect, the ideal state of energy-consuming passive balancing can only prevent small-capacity batteries from overcharging. However, in fact, since the shunt current of this technology is very small, it is almost negligible compared with the charging current of several amperes or even tens of amperes, and the balancing effect during charging is negligible, especially for electric vehicle 402030 batterys using fast charging technology, the overcharging problem still exists. In comparison, due to the large balancing current, the voltage balancing effect of charging balancing during charging is better than that of energy-consuming passive balancing; while the transfer active balancing solves the problems of charging balancing, discharging balancing and static balancing at the same time in technology, and has the best actual application effect.

The biggest defect of energy-consuming passive balancing and charging balancing is that they cannot solve the problem of over-discharging of small-capacity batteries, and their application is limited.

Due to the existence of consistency problems, the voltage rise and fall speeds of batteries of different capacities are different, which causes overcharging and over-discharging of individual batteries and forms a vicious cycle. Batteries with reduced capacity are commonly known as lagging batteries or attenuated batteries. Attenuated batteries have the characteristics of small capacity and large internal resistance. Whether during charging or discharging, their heat generation is the highest. When the temperature is too high, "thermal runaway" failures are likely to occur, causing explosions, fires and other accidents. For temperature rise caused by internal resistance, in theory, if the actual charge and discharge current of the attenuated battery can be reduced without affecting the charge and discharge current of the 402030 battery, then the temperature rise of the attenuated battery will be reduced, thereby reducing the probability of "thermal runaway" and improving the operating safety of the 402030 battery. In practice and testing, it was found that when the charge and discharge current of the "lagging" battery is reduced through human intervention, the actual temperature rise and voltage rise and fall speed of the "lagging" battery will be effectively improved and controlled. The greater the current intervention, the more obvious the effect of voltage consistency and temperature rise improvement. From the perspective of automation implementation, to achieve this goal, the battery balancer is required to have a large current shunt capability. The only feasible battery balancing technology is the transfer active balancing technology.

Passive balancing and charge balancing are essentially charge balancing, which is only applicable to the balanced charging of 402030 batterys. If the balancing current is significantly different from the actual charging current, the charge balancing effect will be affected, and the overcharging problem cannot be avoided. In particular, the passive balancing has a very small balancing current and a late balancing intervention time. It can be almost ignored for charging currents of more than ten amperes or even tens of amperes or higher. These two balancing technologies have inherent technical defects and have no voltage balancing ability during discharge and static periods, and their development is limited. Active balancing (excluding passive balancing in active control mode) technology is a more comprehensive and practical battery balancing technology, especially making up for the shortcomings of charge balancing, which is suitable for almost any 402030 battery and is the development trend of battery balancing technology.

The attached figure is a voltage comparison diagram of the same 13-string 402030 battery at the end of discharge under the same charging standard (balanced charging) and discharge standard (1A constant current discharge). Figure 1 is a voltage distribution diagram of the 402030 battery when it is discharged for 36 minutes (end of discharge). The voltage data shows that the voltage difference between the batteries is large, and the maximum voltage difference is close to 0.6V. Most batteries still have a lot of power that has not been effectively released, and the capacity is seriously wasted.

After using the high-efficiency transfer battery equalizer, the actual discharge time is as long as 58 minutes, which is much longer than the conventional discharge time. The voltage distribution at the end of balanced discharge is shown in Figure 2. It can be clearly seen from the residual voltage of each battery that the voltage consistency of the 402030 battery at the end of balanced discharge is still very good, with a maximum voltage of only 71mV. The voltage distribution is reasonable, which is significantly better than conventional discharge. Not only is the actual discharge time significantly extended, but the voltage consistency at the end of discharge is also very good.

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