Fast charging method, charging current for the conventional charge current for several times. Sufficient power, if not promptly stop fast charging, the battery temperature and internal pressure will increase rapidly. The internal pressure is too large, sealed batteries will play an open porosity, so that the electrolyte oven, resulting in electrolyte viscosity was increased, and the battery internal resistance increases, the capacity decrease.

From the nickel-cadmium battery fast charge feature can be seen that, after fully charged, the battery voltage began to decline, the battery temperature and internal pressure rising rapidly, in order to ensure the Dell latitude d620 Battery is fully charged, but also the charge can be used from time to time control, voltage control and temperature control to be more than methods.

(1) Timing Control

With 1.25C charge rate, battery-1h can be sufficient; using 2.5C charge rate, when, 30min may be sufficient. Thus, according to the battery capacity and charge current, it is easy to determine the required charging time. This control approach is the most simple, but since the beginning of the battery charge state are not identical, and some charge a battery shortage, some of the battery before charging, so only when the charging rate of less than 0.3C only allows the use of this approach.

(2) voltage control

In the voltage control method, the most easily detected is the highest voltage of the battery. The voltage control method commonly used are:

The maximum voltage (Vmax) can be seen from the characteristic curve of charge, the battery voltage reaches its maximum when the battery that is fully charged. Charging process, when the battery voltage reaches the specified value, should immediately stop fast charging. This control method's weaknesses are: the battery fully charged the maximum voltage with ambient temperature, charging rate of the change, but each single cell battery pack the maximum charge pressure is also a difference, so this method can not be very accurately determine the battery have sufficient charge.

Voltage negative increment (-ΔV) due to the negative battery voltage increment and the absolute voltage of the battery pack has nothing to do, but also from environmental factors such as temperature and charge rate of the impact, so you can more accurately judge the battery is fully charged. This control method's weaknesses are: the battery voltage is a negative increment, the battery has been charging, so the battery at higher temperatures. In addition, Ni-MH battery fully charged, the battery voltage to go through a longer time before a negative increment, over-charge more serious. Therefore, this control method is mainly applied nickel-cadmium batteries

Voltage and zero-increment (0ΔV) Ni-MH battery charger, in order to avoid the wait for a negative increment of voltage it takes too long and damage the battery, usually 0ΔV control laws. Disadvantage of this approach are: fully charged before the battery voltage is within a certain period of time may be very few changes, resulting in the premature termination of fast charge. To this end, at present most of the Ni-MH battery charger have adopted fast-0ΔV highly sensitive detection, when the battery voltage is slightly lower, the immediate cessation of fast charging.

(3) temperature control

In order to avoid damage to the battery, the battery temperature is too low when you can not start fast charging, the battery temperature rises to the required values, you must immediately stop fast charging. Temperature control methods commonly used are:

Maximum temperature (Tmax) during charging, usually when the battery temperature reaches 55 ℃, they should immediately stop fast charging. The temperature of the battery can be fitted together with the battery thermistor to detect. Disadvantage of this approach is the thermistor response time longer, the temperature tests, a certain lag, at the same time, the Dell latitude d820 Battery has a maximum operating temperature and environment temperature. When the ambient temperature too low, adequate power, the battery temperature reach 55 ℃.

Temperature rise (ΔT) in order to eliminate environmental impact, temperature control method can be used. When the cells reach the required temperature rise of the value immediately after the cessation of fast charging. In order to achieve temperature control, must use two thermistors were used to detect the battery temperature and ambient temperature.

Temperature change rate (ΔT / Δt) nickel metal hydride and nickel cadmium batteries fully charged, the battery temperature rose rapidly, but rose at a rate ΔT / Δt is basically the same, when the battery temperature rise 1 ℃ per minute, it should immediately terminate the fast charging, this charge control method, widely used in recent years. It should be noted, due to the thermistor resistance and temperature relationship is nonlinear, therefore, in order to improve detection accuracy should try to reduce the thermal resistance of non-linear effects.

Minimum temperature (Tmin) when the battery temperature is below 10 ℃, the use of high-current fast charging, it will affect battery life. In this case, the charger should automatically be transferred to trickle charge until the Dell inspiron b130 Battery temperature rises to 10 ℃ after, then transferred to fast charging.

(4) Integrated Control

The advantages and disadvantages of various control methods. To ensure that under any circumstances, can accurately and reliably control the battery charging, and currently commonly used in rapid chargers, including timing control, voltage control and temperature control of an integrated control laws.