Study on Fast Charging Method of Lead-Acid Battery
5th International Conference on Environment, Materials, Chemistry and Power Electronics (EMCPE 2016)
Study on Fast Charging Method of Lead-Acid Battery for Electric Vehicle
Yuanpeng Zhu1, a
1
School of Automotive Engineering, Wuhan University of Technology, Wuhan 430070, China
a
[email protected]
Keywords: electric vehicle; lead-acid battery; fast charging method
Abstract. The lead acid batteries used by electric vehicles have always presented the problem of low
efficiency and high loss. In order to promote the popularization and application of electric vehicles,
many researchers have put forward the fast charging method of battery. Based on this understanding,
the fast charging principle of battery was analyzed in this paper, and the depolarization pulse fast
charging method and the high current decline fast charging method were studied, so as to provide
reference for the people interested in the topic.
1. Introduction
The lead-acid battery as a kind of battery with mature technology and low cost has been applied in
electric vehicle. However, electric vehicle has always presented the problem of short mileage with
charging once, which has hindered the development of electric vehicle. In addition, the battery will
suffer from rapid temperature rise which ultimately affects the battery life instead of reaching the
rated capacity only through increasing the charging current and shortening the charging time.
Therefore, it is necessary to strengthen the study on fast charging method of lead-acid battery for
electric vehicle, in order to better promote the development of electric vehicles.
2. Analysis of the fast charging principle of lead-acid battery for electric vehicle
In practical applications, the lead-acid batteries for electric vehicles use the constant current
charging, constant voltage charging, phased charging and other conventional charging methods.
Although it is easier to implement the conventional charging methods and control them simply, more
than ten hours of charging time is needed, which not only affects the use of electric vehicles, but also
damages the batteries. In addition, according to the technical parameters of lead-acid battery
proposed by the Advanced Lead Acid Battery Consortium (ALABC) (as shown in Table 1), these fast
charging methods cannot meet the demand of the battery for electric vehicle.
Table 1: technical parameters of lead-acid battery
Charging
Requirements
Charging
Time
50% Capacity
80% Capacity
80% Capacity
5min
15min
4h
2.1 Analysis of main factors hindering the battery charging
As can be seen from the analysis of the reasons hindering the battery charging, polarization
phenomenon will appear between the two poles in the late charge. At this time, the potential
difference between the two poles will be higher than the equilibrium electrode potential of the active
substance, thereby influencing the battery charging capacity. With the increase of charging current,
electrochemical polarization reaction will increase significantly, thereby decreasing the battery
charging capacity [1]. Thereby, it is necessary to seek ways to eliminate the battery polarization
phenomenon, rather than simply increase the charging current, so as not to affect the service life of
the battery.
© 2016. The authors - Published by Atlantis Press
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2.2 Fast charging principle of lead-acid battery
As can be seen from the analysis of battery charging process, the acceptable charging current of
i  Ie t
the battery decreased with the time. The formula for calculating the charging current is c
, of
which ic is the charging current, I0 is the maximum acceptable charging current of the battery at time
0, and α is the attenuation coefficient. Therefore, it is necessary to ensure that the charging current is
always in the range of the maximum charging current of the battery, so that the battery is in the best
state of acceptance. In the case of the charging time is 0, the battery can accept the maximum
charging current. Therefore, in the early stage of charging, larger charging current can be used [2].
Currently, the fast charging methods of lead-acid battery can be divided into two kinds, namely pulse
fast charging method and high current decline fast charging method.
3. Fast charging methods of lead-acid battery for electric vehicle
3.1 Depolarization pulse fast charging method
The so-called depolarization pulse fast charging method, in fact, realizes short stop charging in the
process of high current charging and adds discharge pulse in the process of stop charging. In the
charging process of lead-acid battery, addition of negative pulse with certain height, width and
frequency in the current can increase the concentration of lead ions participating in reaction, and
moves other negative ions away from the electrode surface, so as to reduce the probability of
polarization phenomena, and therefore increase the acceptable charging current of the battery. As
shown in Fig. 1, curve 0 is the acceptable charging current curve at the deep discharge phase of the
battery; curve 1, 2, 3 and 4 are the acceptable charging current curves of the battery after charged for
a period of time and discharge of negative pulse. As can be seen from the figure, other curves shift
right compared with curve 0. This phenomenon means that the battery charging capacity is enhanced.
Fig. 1: acceptable current changes of negative pulse depolarization
According to the charging principle of depolarization pulse fast charging method, it is found that
the charging current of this kind of charging method is larger. With the increase of the battery
capacity, terminal voltage of the battery will also increase. After the completion of the first phase of
the charging, you can stop charging 25-40ms, in order to completely eliminate the ohmic polarization
and partial concentration polarization. Subsequently, reverse charge can be conducted, making the
battery pass through the larger pulse current [3]. The width of the pulse current is 25-200ms, and the
amplitude is 2-5 times of the charging current, which can further eliminate the concentration
polarization. After the stage charging is completed, 25ms of stop discharging can be conducted again,
and then the cycle charge of positive pulse charging-forward pause-negative pulse discharge-rear
pause-positive pulse charging can be conducted until the battery voltage reach a certain value.
In order to study the charging effect of depolarization pulse fast charging method, charging test
can be conducted by means of 2V/200Ah lead-acid battery. Specifically, 25ms of pause was
conducted after charged 2min by using 170A current. Then, 50ms of negative pulse discharge was
conducted by using 300A current, and 25ms of pause was conducted. On this basis, high current
charging can be continued, and cycle charging can be conducted. As shown in Table 2 below, output
capacity of the battery would reach 61% after the actual charge of 90min. However, it takes 8 hours to
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reach the output capacity by using the conventional constant current charging method. Therefore, it
can be seen that the application of the depolarization pulse fast charging method has achieved certain
results.
Table 2: effect of depolarization pulse fast charging method
Charging
Time/h
0
0.3
0.6
0.9
1.5
2.0
3.0
Terminal Voltage/V
Charging Current/A
Capacity/Ah
11
13
15
16
17
18
18
170
170
170
170
60
10
5
0
47
92
132
159
164
169
3.2 High current decline fast charging method
For the charging acceptance ratio of the battery a=I0/C, C is the battery capacity. In the case of
smaller battery capacity, the charging acceptance ratio of the battery will increase obviously.
Therefore, the high current decline fast charging method realizes charging by using the high current
in the initial stage of charging based on the feature of the battery in the low state of charge [4]. With
the increase of charging time, current difference will gradually reduce, and ultimately be lower than
certain current value, until the battery capacity is sufficient.
In order to study the application effect of the high current decline fast charging method, 300Ah
battery can be used as an example to charge the battery with 500A current. During the charging
process, the current is reduced by using 50A difference at regular time, until the current reduces to
100A. As shown in Fig.2 below, the graph shows a charging curve of the high current decline fast
charging method; the output capacity of the battery will reach 63% when the charging time reaches
46min.
Fig. 2: charging curve of the high current decline fast charging method
Conclusion: all in all, shortening the charging time of lead-acid battery will be conducive to the
application of electric vehicles. Currently, however, there is no more mature charging technology in
the fast charging of lead-acid batteries in electric vehicles. Although the depolarization pulse fast
charging method and high current decline fast charging method can shorten the charging time of
lead-acid battery to a certain extent, they are not able to reach the charging requirements of lead-acid
batteries proposed by the Advanced Lead Acid Battery Consortium (ALABC). Therefore, it is
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believed that with the development of related technologies, the fast charging method of battery will
be further developed, so as to better meet the needs of the development of electric vehicles.
References:
[1] Chen Hao, Guo Lijin and Li Hui, Intelligent Charging and Its Strategy for Lead-Acid Batteries of
Electric Vehicles [J]. Electronic Science and Technology, 2012, 11:79-81.
[2] Ma Yongquan, Liu Xiaowei, Chen Tixian et al. Research on Lead-Acid Batteries for New Energy
Vehicles [J]. Battery, 2011, 03:99-103.
[3] Wang Jian, Lv Rongguan and Jiao Changmei, Study on Battery Charging and Its Management for
Electric Vehicles [J]. Battery, 2011, 05:230-236.
[4] Duan Zhaowei, Zhang Lei and Liu Gang, Design of Pulse Fast Charging System for Lead-Acid
Batteries of Electric Vehicles [J]. Process Automation Instrumentation, 2013, 07:75-77.
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