Forklift lithium battery charge and discharge technology
Forklift lithium battery charge and discharge technology
Zibo torch 40 - lithium-ion batteries
5 db500/80 v500ah, 3 tons of heli forklift battery forklift most lithium-ion battery pack with different combinations of voltage, wide range of USES, is the preferred power source for all kinds of mechanical equipment, charging and discharging technology is key, can be a decisive impact on the whole battery life, many users new forklift battery life and time is not ideal, affected by many factors, we simple analysis under several elements: if the battery is lower than single less than half of the average life span, can be concluded that is due to improper use of technology, primary reason when the push through the charge and discharge monomer battery failure ahead of time.
Monomer battery as power source, such as mobile communications, power management technology has been very perfect, but in the lithium battery pack, the difference between monomer is always present, capacity, for example, the difference will never tend to disappear, but is gradually deteriorating.
Group through the same current, relatively large capacity is always in shallow shallow filling, tend to be small current capacity attenuation, longevity, slow and small person is always in large current charge discharge capacity, tend to capacity attenuation speed, shorten the life, the performance parameters of the differences between more and more big, form positive feedback characteristic, small capacity failure ahead of time, shorten the life.
Charging at present is mainly pressure limiting current limit method, constant current (early
Strongest rechargeable battery accept ability, mainly for the endothermic reaction, but the temperature is too low, the active material is reduced, can enter the constant current phase in advance, so cold in winter in the north, the battery before charging preheat improves the charging effect.
Strengthened with continuous charging process, the polarization effect, temperature rise, along with gas chromatography, electrode overpotential increases, voltage rise, when charged to about 70 ~ 80%, reached the highest voltage charging voltage limit, into the constant pressure,
In theory there is no objective of charging voltage threshold, if understood as analysis, gas heating means overcharge, late in the constant current phase happen to different degrees of overcharge, 40 ~ 50 degrees Celsius temperature, sensor shell deformation easily, part of the escaping gas can also be compound, others as a result of the irreversible reaction, loss of capacity, it can be seen as current strength than battery capacities.
At constant pressure stage, has said a trickle charging, cost about 30% of the time filling the 10% of the battery, current strength decreases, and analysis, temperature no longer increases, and changes in the opposite direction.
For overcharge lithium battery forklift, at the time of inspection, single voltage high, relative to other cells in the group has entered a stage of charging.
Before charging, except in the constant current phase, due to the current intensity, voltage, temperature, increasing internal pressure, if continue to overcharge, air valve opening, and irreversible reaction temperature continues to rise.
Constant voltage phase, the current strength is lesser, overcharge symptoms than constant current phase is remarkable.
As long as the temperature rise, high internal pressure, is associated with side effects, battery capacity will reduce, and the adverse event has inertia, development to a certain extent, may be in charge or the charge the battery in a short time after the matter inside burning, lead to dead batteries.
Charging speed battery capacity attenuation, lead to battery failure, vile indeed.
Torch forklift lithium-ion battery pack for excessive discharge using the forklift lithium-ion battery pack wire resistance and contact resistance and voltage continues to fall, after a period of time, to reach new electrochemical balance, into the discharge plateau, voltage change is not obvious, the exothermic reaction and resistance heat makes the battery temperature rise is higher.
Discharge voltage curve approximation monomer discharge curve, continue to discharge, the voltage curve into horsetail decline phase, polarization impedance increases, the output efficiency is reduced, heat consumption increases, close to stop discharging termination voltage.
Consider single cells in the group, there will be a relative discharge conditions.
Late in the discharge, the voltage is close to horsetail curve, single capacity of normal distribution and voltage distribution is complex, the smallest capacity monomer voltage sags are the earliest, the fastest, if the battery voltage is not very obvious, the other small capacity monomer voltage drop were obscure, has been excessive discharge.
After discharge, observe monomer into horsetail curve, if continued large current, voltage reduced quickly, and soon the reverse, when the battery charge is the opposite direction, or passive, active material structure is broken, another side effects happen quickly, over a period of time, the battery active material is close to all loss, equivalent to a passive resistance, voltage is negative, the numerical equivalent to reverse charge flow on the equivalent resistance of pressure drop and stop after discharge, the galvanic battery electromotive force disappears, the voltage can't recover, therefore, a reverse charge enough to make a battery scrap.
Paper summarizes: forklift lithium battery overcharge had put the damage to the battery is fatal, the difference only lies in the overcharge to produce large amounts of gas, easy spontaneous combustion and explosion, representation, a gentle appearance change, but the failure rate is very fast, in normal use should be strictly avoided.
In view of the raw materials, with the same batch of monomer battery, capacity, internal resistance, performance parameters, such as life accord with normal distribution and discrete degree is limited;
Given under the condition of same current incentives, the consistency of the monomer battery voltage change process gradually approaching the consistency of other performance parameters, one of the most important parameter is the degree of charged;
Given battery at never after have the damage, etc. To top it off in their lifetime is not easy to early failure, can be concluded that if by energy transformation in the process of charging and discharging voltage balance control method in the implementation of the battery pack monomer, monomer voltage, then the extent of monomer relative charged, tend to be consistent, can achieve adequate electricity, at the same time also empty electricity, in turn, the service life of the battery pack can approximate to monomer average life expectancy of the battery.
Source: the lithium battery forklift truck;
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