|
Lithium-ion is found in cell phones and mobile computing. Increasing internal Resistance The capacity of a battery defines the stored energy - the internal resistance governs how much energy can be delivered at any given time. While a good battery is able to provide high current on demand, the voltage of a battery with elevated resistance collapses under a heavy load. Although the battery may hold sufficient capacity, the resulting voltage drop triggers the 'low battery' indicator and the equipment stops functioning. Heating the battery will momentarily increase the output by lowering the resistance. A battery with high internal resistance may still perform adequately on a low current appliance such as a flashlight, portable CD player or wall clock. Digital Camera battery equipment, on the other hand, draw heavy current bursts. Figure 2 simulates low and high internal resistance with a free-flowing and restricted tap. Figure 2: Effects of internal battery resistance.A battery with low internal resistance is able to provide high current on demand. With elevated resistance, the battery voltage collapses and the equipment cuts off. Nickel-cadmium offers very low internal resistance and delivers high current on demand. In comparison, nickel-metal-hydride starts with a slightly higher resistance and the readings increase rapidly after 300 to 400 cycles. Lithium-ion has a slightly higher internal resistance than nickel-based batteries. The cobalt system tends to increase the internal resistance as part of aging whereas the manganese (spinel) maintains the resistance throughout Apple laptop battery life but loses capacity through chemical reaction. Cobalt and manganese are used for the positive electrodes. High internal resistance will eventually render the battery useless. The energy may still be present but can no longer be delivered. This condition is permanent and cannot be reversed with cycling. Cool storage at a partial state-of-charged (40%) retards the aging process. The internal resistance of Lead-acid batteries is very low. The A1175 A1185 battery responds well to short current bursts but has difficulty providing a high, sustained load. Over time, the internal resistance increases through sulfation and grid corrosion. Elevated self-discharge All HP laptop batteries suffer from self-discharge, of which nickel-based batteries are among the highest. The loss is asymptotical, meaning that the self-discharge is highest right after charge and then levels off. nickel-based batteries lose 10% to 15% of their capacity in the first 24 hours after charge, then 10% to 15% per month afterwards. One of the best batteries in terms of self-discharge is Lead-acid; it only self-discharges 5% per month. Unfortunately, this chemistry has the lowest energy density and is ill suited for portable applications. ACER Laptop Battery DELL Laptop Battery HP Laptop Battery TOSHIBA Laptop Battery
Related Articles -
laptop, battery,
| 
