Thin, high capacity, long life, these are the outstanding characteristics of lithium batteries. For this reason, lithium-ion battery, it has rapidly replaced the nickel-metal hydride, nickel cadmium batteries role as notebook computers and other portable devices optimized for life. Near was a time when the laptop battery continuously be exposed bombings will be laptop battery time and again pushed the cusp, the user has this lingering fear, lithium batteries in the end is a source of power or a bomb?
Find study battery fire mystery
In general, the current notebook lithium battery pack itself has a more complete protection.
It is not only from the string / multiple batteries in parallel composition, itself contains two kinds of circuit board modules: protection circuit substrate (Protection PCB) module and the Smart Battery Gauge Board module, its design includes a set of first-class battery protection protection IC (to prevent battery overcharge, over discharge, short circuit), the second-level protection IC (to prevent a second over-voltage), fuses, LED direction, temperature regulation and other components.
In a multi-level protection mechanism, even in the power charger, notebook computers unusual circumstances, the laptop battery can only be converted to automatic protection status, if the situation is not serious, often still work after re-plug, not will be an explosion. laptop battery exploded in the face of serious facts, the reporter sought the advice of professionals, as well as electro-chemical a well-known manufacturers of design engineers.
According to the analysis, lithium batteries is nothing less than an explosion caused by a short circuit or overcharge, the greatest likelihood of a lithium battery in the manufacturing, because of manufacturing process itself flawed, leaving the existence of product safety problems that may occur at any time, for example should be insulation between the poles of metal dust or a copper foil and aluminum foil pierced the membrane of the burr, resulting in micro-short circuits. The former situation is most serious, it will directly result in short-circuit, and a large number of heat production, resulting in vaporization of some of the electrolyte, the battery shell stretch.
In addition, there is a rather special case, the power charger or a laptop due to special reasons, the instant to the lithium batteries provide high-voltage / high current leading to a serious over-charge, if charging voltage from 12.6V sudden rise to 12.9V or even higher, when there will be a high charging current generation, the battery should be within the circuit moves to cut off charging current, but because part of the lithium battery charging over-voltage, over-current protection function design is weak, which may lead to the battery protection IC is damaged, so that to protect the laptop battery so that the function of damaged, over-charge on-chip over the posterior pole needle-shaped lithium metal crystal, piercing points, resulted in a number micro-short circuit, causing the battery temperature gradually increased, until eventually the battery explosion, fire phenomenon, This is currently a lot of laptop battery "hot" the main reason.
Add a layer of umbrella cover
At present, the battery protection mechanisms from the point of view, battery charging in front of some of the traditional chip vendors to play most of the programs are precise control of charging voltage and charging current role in the over-voltage and over-current control, and does not provide the corresponding solution. In this way, the protection of the battery pack is entirely dependent on the battery itself, such as overcharge protection, over-discharge protection, over-charging current protection, over-discharge-current protection, over-temperature protection and so forth.
Protection in place need to prevent first-level protection IC failure or MOSFET short-circuit caused by over-voltage fault, so the second-level protection IC will normally be considered to protect the battery group of the last line of defense. In this regard, Bump E (O2 Micro) Product Manager, Hong Shi Zhen expressed different views, he believed that the protection for the battery pack can move forward, through the charger additional control functions to achieve detection and control of the battery charge movements, which undoubtedly will further enhance the protection level, to the protection of lithium batteries to use security.
To this end, in the O2 Micro power management for portable devices developed by Cool Charge solution which combines the one called Cool Battery Technology battery protection technology, and its most significant feature is to have a traditional chargers generally do not have the OVP (over Voltage Protection) and OCP (Over Current Protection) function of the two battery protection, this technology has been embedded among the Cool Charge IC chip.
After the adoption of Cool Charge IC chip, the power charger will largely assume the responsibility to protect the battery. Subject to the Cool Charge IC control, charger, compared with the traditional design (see Figure 1), the required external components significantly reduced eliminates the need for Q3 and Q4 part of the design, reducing the failure rate. In Q1 preserved and Q2 (components to improve the original design) between, Cool Charge IC set up a detection point, through the factory setting, the detection point voltage and current settings are slightly less than the battery manufacturers to set safety requirements. Thus, in the charge voltage or current exceeds the Cool Charge IC to set the security after the voltage or current value, IC on the control of Q2 off, the first battery protection cut off before the charge; from detecting the frequency point of view, the battery protection, detection time interval in milliseconds level, through-chip detection, can be very easy to achieve millionth of a second level, you can use high frequency of continuous detection, in order to achieve the first step to protect the battery pack purposes.
