Why can not laptop battery maintenance and replacement of batteries?

Construction of laptop battery is not complicated, simply, is that batteries with protection circuit, the battery is the core of batteries in series or in parallel, which we usually see batteries with ordinary cylindrical shape similar to the AA batteries , just inside the store electrical energy in different chemical solutions, manufacturers have designed over current, over voltage, over charge, over discharge, temperature protection. Although the battery structure is simple, but really qualified to make a battery is not that simple. A product must first select the batteries, bad batteries are often internal resistance, voltage, charge and discharge targets difficult to meet the demands, to do out of the products is mixed. At present the formal multi-vendor Sanyo, Samsung, Toshiba, LG, BAK and other brands of batteries. Storage batteries and must be tested for its index, indexes were within 2% to match the composition of batteries in series or parallel circuit, otherwise, as an indicator of batteries and other batteries are quite different in the laptop battery charge the performance of the discharge process for the battery will not charge or discharge of success, and this alone has been over-charging or batteries discharge, resulting in the battery pack is not working properly, the difference in the long term the larger batteries over charging or discharging , the possible leakage or explosion. Manufacturers of batteries for testing and matching of precision instruments, not the City general computer maintenance personnel rely on the so-called professional multimeter to be able to complete, and they rely on the multimeter can be achieved at the most is the internal resistance of the batteries within the control precision is needed, as actual storage capacity of batteries, lifetime, charge and discharge the effective time, no professional equipment can not detect the true sense can not be paired, but also form the so-called maintenance, the battery storage capacity has not increased maintenance will not .