Abstract: In view of accumulator cell’s characteristic, has studied in the accumulator cell charging and discharging process phenomenon of polarization, proposed and has analyzed several charge ways, and has forecast its prospects for development.
Key word: Accumulator cell; Charge; Polarization
Introduction
The lead-acid battery is low as a result of its production cost, the capacity is big, 
the low in price obtained the widespread use. But, if uses improper, its life will reduce greatly. The influence lead-acid battery life’s factor are many, but selects the correct charge method, can lengthen accumulator cell’s service life effectively.
The research discovered: The battery charging-up is biggest to the battery life influence, discharge process’s influence are few. That is, the overwhelming majority accumulator cell not wears out, but is “sufficient bad”. Thus it can be seen, a good battery charger has the pivotal function to accumulator cell’s service life.
1 battery charging rationale
In the mid-1960s, American scientist Mas has done the massive experimental study to the aperture accumulator cell’s charging-up, and proposed take the lowest gas efficiency as the premise, the accumulator cell acceptable charge pattern, as shown in Figure 1. The experiment indicated that if the charging current according to this curve change, may reduce the duration of charging greatly, and has not affected to battery’s capacity and the life. In principle is called this curve the best charge pattern, thus has established rapid charge rate method research direction [1,2].
May see by Figure 1: The initial charging current is very big, but weakens very quickly. The primary cause was in the charging-up has had the phenomenon of polarization. In the sealed type battery charging process, the interior produces the oxygen and the hydrogen, when the oxygen cannot absorb promptly, then piles up in the positive plate (positive plate produces oxygen), causes the battery internal pressure to enlarge, the battery temperature rise, simultaneously reduced positive plate’s area, the performance is the interface resistance rise, presents the so-called phenomenon of polarization.
The accumulator cell is reversible. Its electric discharge and the charge reaction formula is as follows:
PbO2 Pb 2H2SO42→PbSO4 2H2O (1)
Very obviously, the charging-up and the discharge process are back reactions mutually.
The reversible process is the thermodynamics balance process, to safeguard the battery to be able to maintain throughout under the state of equilibrium charges, must enable to pass battery’s electric current small somewhat as far as possible. The ideal conditions are the external voltage are equal to battery’s electromotive force. But, the practice indicated that when battery charging, the external voltage must increase to certain value is only then good, but this value because of the electrode material, the solution concentration and so on each kind of factor’s difference in varying degrees has surpassed accumulator cell’s balanced electromotive force value. In the chemical reaction, this kind of electromotive force surpasses thermodynamics equilibrium value the phenomenon, is the phenomenon of polarization.
Generally speaking, has the phenomenon of polarization to have 3 aspect reasons.
1) in ohmic polarization charging-up, positive and negative ion to two-pole migration. Receives certain resistance inevitably in the ionic migration process, is called the ohm interface resistance. In order to overcome this interface resistance, the external voltage must extra exert certain voltage, by overcome resistance impetus ionic migration. This voltage gives the environment by the heat way transformation, presents the so-called ohmic polarization. Enlarges suddenly along with the charging current, the ohmic polarization will create accumulator cell’s in charging-up high temperature.
when 2) the density polarization current winds through the accumulator cell, is the maintenance normal response, the most ideal situation is the electrode surface reactant can obtain the supplement promptly, the resultant can depart promptly. In fact, the resultant and the reactant propagation rate does not compare the rate of chemical reaction by far, thus causes nearby the pole plate the electrolyte solution density to change. That is, from the electrode surface to the middle solution, the electrolyte density distributes non-uniform. This kind of phenomenon is called the density polarization.
3) the electrochemistry polarizes this kind of polarization is because on the electrode carries on the electrochemistry response’s speed, 
falls behind on the electrode the electron motion speed creates. For example: Before battery’s cathode electric discharge, the electrode surface has the negative charge, its nearby solution has the positive charge, both are at the state of equilibrium. When electric discharge, has the electron liberation to give the external circuit immediately. The electrode surface negative charge reduces, but the metal dissolves the oxidizing reaction carries on slow Me-e 鯩 e , cannot supplement promptly the electrode surface electron the reduction, the electrode surface charge state changes. This kind of superficial negative charge reduces the condition promotion metal neutron leaves the electrode, metallic ion Me changes over to the solution, accelerates Me-e 鯩 the e response to carry on. Always one time, achieves the new dynamical equilibrium. But compares before the electric discharge, the electrode surface had the negative charge diminution in number, changed positive with this correspondence’s electrode potential. Is also the electrochemistry polarizing voltage changes high, thus has hindered the normal charging current seriously. When likewise, battery positive electrode electric discharge, the electrode surface has the positive charge diminution in number, the electrode potential changes negative.
These 3 kind of phenomenon of polarization is along with the charging current increases, but serious.
2 charge method research
2.1 conventional mise-a-la-masse methods
Before the conventional charge system rested on 1940, the internationally recognized empirical rule design. And most famous is “the ampere-hour rule”: The charging current amperage, should not surpass the accumulator cell to treat the charge the ampere hour number. In fact, the conventional charge’s speed limits by accumulator cell’s in charging-up temperature rise and the gas production.
This phenomenon to the battery charging must the shortest time has the important meaning.
Generally speaking, the conventional charge has the following 3 kinds.
2.1.1 constant flow mise-a-la-masse methods
The constant flow mise-a-la-masse method is with the adjustment charging set output voltage or the change and the accumulator cell series resistance method, maintains the charging current intensity invariable charge method, as shown in Figure 2. The control method is simple, but because the battery may accept the electric current ability is along with the charging-up carries on but drops gradually, to the charge later period, the charging current uses in the brine electrolysis, produces the gas, causes the air vent in excess, therefore, often selects the stage mise-a-la-masse method.
2.1.2 stage mise-a-la-masse methods
This method including two stage mise-a-la-masse methods and three stage mise-a-la-masse methods.
1) two terrace works use the rapid charge rate method which the continuous current and the permanent voltage unify, as shown in Figure 3. First, by the continuous current charge to the predetermined voltage value, then, changes the permanent voltage to complete the surplus charge. Generally between two stage’s transformation voltages are the second stage permanent voltages.
2) three stage mise-a-la-masse methods when the charge starts and finished to use the continuous current charge, middle charged with the permanent voltage. When decay of current to predetermined value, transforms from the second stage to the third stage.
This method may reduce to few air output, but takes one kind of rapid charge rate method use, receives certain limit.
2.1.3 constant pressure mise-a-la-masse methods
Charging source’s voltage maintains the constant value completely in the duration of charging, along with accumulator cell terminal voltage’s gradual elevation, the electric current reduces gradually. Compares with the constant flow mise-a-la-masse method, its charging-up approaches in the best charge pattern. With the constant voltage rapid charge rate, as shown in Figure 4. Because the charge initial period accumulator cell electromotive force is low, the charging current is very big, along with charge advance, the electric current will reduce gradually, therefore, only needs the simple control system.
This kind of charge method brine electrolysis were very few, avoids the accumulator cell being excessively sufficient. But is oversized in the charge initial period electric current, has the very tremendous influence to the accumulator cell life, and easy to cause the battery plate to be curving, creates the battery abandonment.
In view of the fact that this kind of shortcoming, the constant pressure charge very little uses, only then, in the charging source voltage is low, but the electric current is big time uses. For example, in the automobile movement process, the accumulator cell is by the constant pressure mise-a-la-masse method charge.
2.2 rapid charge rate technologies
For can maximum limit speed up accumulator cell’s rate of chemical reaction, 
reduces the accumulator cell to achieve the occupied state the time, simultaneously, guaranteed that accumulator cell positive and negative pole plate’s phenomenon of polarization as far as possible few or light, raises the accumulator cell use efficiency. The rapid charge rate technology obtained the rapidly expand in recent years.
Following introduction at present quite popular several rapid charge rate method. These methods revolve the best charge pattern to carry on the design, the goal is causes its charge pattern to close on the best charge pattern as far as possible.
2.2.1 pulse type mise-a-la-masse method
This kind of mise-a-la-masse method not only follows the accumulator cell inherent charge receptance, moreover can raise the battery charging receptance, thus broke the accumulator cell index charge to accept the curve the limit, this was also the battery charging theory recent development.
The pulse charge way first is with the pulse current to the battery charge, then lets the battery stop sufficient period of time, so circulates, as shown in Figure 5. The charge pulse causes the accumulator cell to fill the electric quantity, but the dormant period causes the accumulator cell the oxygen which and the hydrogen produces after the chemical reaction has the time chemical combination to absorb again, causes the concentration polarization and the ohmic polarization obtains naturally eliminates, thus reduced accumulator cell’s intrinsic pressure, enables the next round the constant flow charge to carry on smoothly, enables the accumulator cell to be possible to absorb more electric quantities. The intermittent pulse enables the accumulator cell to have the full reaction time, reduced has analyzed the spirit, enhanced accumulator cell’s charging current receptance [5].
2.2.2 ReflexTM fast mise-a-la-masse methods
This kind of technology is a US’s patented technology, it mainly faces the charge object is the nickel cadmium cell. Because it has used the new charge method, has solved the nickel cadmium cell’s memory effect, therefore, reduced accumulator cell’s rapid charge rate time greatly. Lead-acid battery’s charge method and has the very big difference to the charge condition’s examination method and the nickel cadmium cell, but between them may profit from [3] mutually.
As shown in Figure 6, a ReflexTM mise-a-la-masse method’s action cycle including the forward charge pulse, the reverse instantaneous discharge pulse, stops maintains 3 stage [3] sufficiently.
2.2.3 change the electric current intermittence mise-a-la-masse methods
This kind of charge method establishment in the constant flow charge and in the pulse charge’s foundation, as shown in Figure 7. Its characteristic is charges Duan Gai the constant flow
Changes the electric current intermittence charge section for the limiting pressure. Charge earlier period’s each section uses changes the electric current intermittence charge the method, guaranteed that enlarges the charging current, obtains the major part charge quantity. The charge later period uses decides the voltage charge section, obtains the surcharge quantity, restores the battery to the completely sufficient electrical state. Stops sufficiently through the intermittence, causes the accumulator cell the oxygen which and the hydrogen produces after the chemical reaction has the time chemical combination to absorb again, causes the concentration polarization and the ohmic polarization obtains naturally eliminates, thus reduced accumulator cell’s intrinsic pressure, enables the next round the constant flow charge to carry on smoothly, enables the accumulator cell to be possible to absorb more electric quantity [4].
2.2.4 change the voltage intermittence mise-a-la-masse methods
In changed the electric current intermittence mise-a-la-masse method in the foundation also some people proposed changed the voltage intermittence mise-a-la-masse method, as shown in Figure 8. With changes the electric current intermittence charge method difference lies in the first stage is not the intermittent constant flow, but is the intermittent constant pressure.
Compared with Figure 7 and Figure 8, may see: Figure 8 conforms to the best charge charge pattern. In each permanent voltage charge stage, because is the constant pressure charge, the charging current defers to the index rule to drop naturally, conforms to the battery circuit to be possible the receptance to carry on along with the charge chases? Drop characteristic [4].
2.2.5 change the voltage changes the electric current wave form intermittence positive and negative zero pulse fast mise-a-la-masse methods
The comprehensive pulse mise-a-la-masse method, the ReflexTM fast mise-a-la-masse method, change the electric current intermittence mise-a-la-masse method and change the voltage intermittence mise-a-la-masse method the merit, changes the voltage changes the electric current wave form positive and negative zero pulse intermittence fast mise-a-la-masse method obtains the development application. The pulse mise-a-la-masse method charging circuit’s control has two kinds generally:
1) pulse current’s peak-to-peak value variables, but PWM (actuation charging and discharging switching valve) the signal frequency is fixed;
2) pulse current peak-to-peak value fixed invariable, PWM signal frequency adjustable.
Figure 9 used one kind to be different with this both’s control model, the pulse current peak-to-peak value and the PWM signal frequency is fixed, PWM dutyfactor adjustable, based on this joined the intermittence to stop the sufficient stage, could imitate in such a short time enters more electric quantities, enhanced accumulator cell’s charge to accept ability.
3 conclusions
The lead-acid battery is in the present world the widespread use one chemistry power source, this product has the good invertibility, the voltage characteristic is steady, the service life is long, the applicable scope is broad, raw material rich (, and renewable use) and construction cost inexpensive and so on merits. The main application in the transportation, the correspondence, the electric power, the railroad, the mine, national economy each departments and so on harbor, is in the social product operative activity the essential product, has the broad prospects for development.
