Single electric lift trucks in the lithium batteries equalizing charge method
Electric lift trucks in the lithium battery is a kind of traction force battery group, with a number of different monomer series voltage used, working strength is much better than the other areas, many users noticed that use after a period of time, the battery monomer in unbalanced state, some capacity is high, some low, once dry, water all monomer proportion of forklift battery density deviation is very far, we have done the following analysis for this phenomenon: a single lithium batteries voltage and capacity is limited, in many cases to form a string to use lithium battery.
But lithium-ion battery pack in the battery balance problem.
How to improve the service life of lithium-ion battery pack, and improve the system stability and reduce the cost, is an important problem in front of us.
Lithium battery life is decided by many factors, one of the most important is the physical properties of the lithium battery itself.
In addition, low battery management technology and unreasonable charging and discharging system is the important cause of shorten battery life.
For lithium-ion battery pack, to remove these reasons, inconsistency between monomer battery is also a important factor.
For lithium battery charging and discharging process of monomer battery imbalance phenomenon, the author analyzed the present several charging methods, combined with the actual catch out of the condition are filling method, and test verification.
Existing equalization charging methods: for each series of lithium battery monomer battery to charge, at present basically has the following several kinds of methods.
In battery balance of each monomer battery attached to a parallel circuit, in order to achieve the effect of shunt.
In this mode, when a battery reaches filled first, balancing device can prevent the overcharge and excess energy into heat energy, continue to fill the battery.
This method is simple, but can bring energy loss, not suitable for fast charging system.
Before charging for each single one by one by the same load discharge to the same level, and then carries on the constant current charging, so that more accurate equilibrium between different monomers.
But for lithium battery pack, due to the physical differences between individuals, each monomer depth ideal difficult to achieve the same effect after discharge.
Even after discharge to achieve the same effect, also can appear in the process of charging the new imbalance phenomenon.
Timing and sequencing, monomer of lithium-ion battery pack alone lithium battery testing and homogeneous charge.
On lithium battery charging, can ensure each of lithium battery lithium battery charging or discharging situation will not happen, and thus guarantees the lithium-ion battery pack each of the lithium batteries are in normal working condition.
Applying the principle of time-sharing control and switch switch components, make additional current into voltage is relatively low in order to achieve the purpose of the equalizing charge in the battery.
This method is efficiency is higher, but control is more complex.
For balanced voltage of each battery parameters, make each battery voltage recovery.
As shown in figure 2, equalizing charge, the capacitance alternately by controlling the switch connected to the adjacent cell, accept high voltage battery charging, then to low voltage battery discharge, until two battery voltage to converge.
This equilibrium method better solve the problem of the battery voltage imbalance, but this method is mainly used in battery fewer occasions.
The whole system controlled by single-chip microcomputer, monomer battery has a set of independent modules.
Module according to the set procedures, the monomer battery charging management respectively, charging is completed automatically disconnect.
The method is simple, but in the long can make the cost greatly increase the number of monomer battery, also go against the decrease of the system volume.
To sum up, there is a kind of method is to use 2 v or 6 v constant current charging machine, the single supplement output current, the proportion of lithium battery forklift modulation and balance of each monomer, voltage is consistent, are filled with the original charger, make sure every single equilibrium.
Shenzhen newshow electric supply co. , LTD.