The secrets of battery runtime

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of the Toshiba Laptop Battery   First post by: www.itsbattery.com

Is the runtime of a portable device directly related to the size of the laptop battery? The answer should be 'yes' but in reality, the battery runtime is governed by other attributes than the specified capacity alone.

This paper examines the cause of unexpected downtime and short battery service life. We look at four renegades - declining capacity, increasing internal resistance, elevated self-discharge and premature voltage cut-off on discharge. We evaluate how these regenerative deficiencies affect nickel, lead and lithium-based batteries such as Toshiba PA3191U-1BAS Battery, Toshiba PA3166U-1BAS Battery, Toshiba PA3331U-1BAS Battery, Toshiba PA3098U-1BAS Battery, Toshiba PA3084U-1BAS Battery, Toshiba PA3399U-1BAS Battery, Toshiba PA3250U-1BAS Battery, Toshiba PA3356U-1BAS Battery, Toshiba PA3291U-1BAS Battery, Toshiba PA3591U-1BAS Battery. Declining capacity The amount of charge a laptop battery can hold gradually decreases due to usage and aging. Specified to deliver 100% capacity when new, the battery should be replaced when the capacity drops to below 80% of the nominal rating. Some organizations may use different end-capacities as a minimal acceptable performance threshold.

The energy storage of a battery can be divided into three imaginary sections consisting of: available energy, the empty zone that can be refilled, and the unusable part (rock content) that increases with aging. Figure 1 illustrates these three sections.

Figure 1: Laptop Battery charge capacity.Three imaginary sections of a battery consisting of available energy, empty zone and rock content.

In nickel-based batteries, the so-called rock content is present in form of crystalline formation, also known as memory. Restoration is possible with a full discharge to one volt per cell. However, if no service is done for four months and longer, a full repair becomes increasingly more difficult the longer service is withheld. To prevent memory, nickel-based batteries should be deep-cycled once every one or two months. Nickel-cadmium and nickel-metal-hydride batteries are used for two-way radios, medical instruments and power tools.

Performance degradation of the lead-acid battery is caused by sulfation and grid corrosion. Sulfation is a thin layer that forms on the negative cell plate if the battery is being denied a fully saturated charge. Sulfation can, in part, be corrected with cycling and/or topping charge. The Battery grid corrosion, which occurs on the positive plate, is caused by over-charge. Lead-acid batteries are used for larger portable devices and wheeled applications.

Lithium-ion laptop batteries lose capacity through cell oxidation, a process that occurs naturally during use and aging. The typical life span of lithium-ion is 2-3 years under normal use. Cool storage a 40% charge minimizes aging. An aged lithium-ion cannot be restored with cycling. Lithium-ion is found in cell phones and mobile computing.

n the chemical cell, chemical energy directly into electricity through the laptop battery is carried out within the spontaneous oxidation, reduction and other chemical reactions the result of the reaction were carried out in two electrodes. Negative active material from the more negative potential and a stable reducing agent in the battery electrolyte composition, such as zinc, cadmium, lead active metals and hydrogen or hydrocarbons. Positive active material from a more positive potential in the electrolyte composition of a stable oxidizing agent, such as manganese dioxide, lead dioxide, nickel oxide and other metal oxides, oxygen or air, halogens and their salts, oxygen-containing acid and its salts etc..

Electrolyte is a good ionic conductivity of the material, such as acids, alkali, salt solution, organic or inorganic non-aqueous solutions, molten salts or solid electrolytes. When the external circuit battery disconnected, although there potential difference between the two poles (open circuit voltage), but there is no current, stored in the batteries do not convert chemical energy into electrical energy. When the external circuit is closed, the two electrodes under the effect of potential difference that there is current flowing through the external circuit. The same time, the battery inside the electrolyte does not exist due to free electrons, charge transfer must be accompanied by two poles active material and battery electrolyte interface, the oxidation or reduction reactions, as well as reactants and reaction products of mass transfer.

Charge transfer in the electrolyte but also by the migration of ions to complete. Thus, within the normal battery charge transfer and mass transfer process is to ensure that the necessary conditions for the normal output of electricity. When charging, the battery inside the transmission power and the direction of mass transfer and discharge exactly the opposite; electrode reaction must be reversible, in order to ensure the opposite direction of mass transfer and mass of the normal electrical Sony PCGA-BP2NX processes. Therefore, the electrode reaction reversible constitutes a necessary condition for batteries.

Reaction for the Gibbs free energy (coke); F is Faraday's constant = 96500 base = 26.8 ampere-hour; n the equivalent number for the battery cell reaction. This is the reaction of the battery and battery electromotive force between the basic thermodynamic relations, but also calculation of cell energy conversion efficiency of the basic thermodynamic equation. In fact, when the current flows through the electrodes, the electrode potential must deviate from the thermodynamic equilibrium of the electrode potential, a phenomenon known as polarization. Current density (unit electrode area adopted by the current), the greater the polarization more serious.

Polarization phenomenon is caused by the battery energy loss of the important reasons. Polarization for three reasons: ‡@ from the battery cells caused by the various parts of the polarization resistance is called Ohm polarization; ‡A from the electrode - electrolyte interface layer caused by charge transfer blocked the process of polarization is called activation polarization; ‡B from the electrode - electrolyte interface layer caused by slow mass transfer of polarization is called concentration polarization. Reduce the polarization method is to increase the electrode reaction area, reducing the current density, increasing reaction temperature and to improve the catalytic activity of the electrode surface.