Some rechargeable batteries can be restored through external means, such as applying a full discharge. There are, however, many defects that cannot be corrected. These include high internal resistance, elevated self-discharge, electrical short, dry-out, plate corrosion and general chemical breakdown.
The performance loss of a battery occurs naturally as part of usage and aging; some is hastened by lack of maintenance, harsh field conditions and poor charging practices. This paper examines the cause of non-correctable battery problems and explores ways to minimize these breakdowns. High Self-discharge
All batteries are affected by self-discharge. This is not a defect per se, although improper use enhances the condition. Self-discharge is asymptotical; the highest loss occurs right after charge, and then tapers off. The percentage of self-discharge can be measured with a battery analyzer but the procedure takes several hours. Elevated internal battery resistance often reflects in higher internal battery resistance, a parameter that can be measured with an impedance meter or the OhmTest program of the Cadex battery analyzers. Shorted Cells
Manufacturers are often unable to explain why some cells develop high electrical leakage or an electrical short while still relatively new. The suspected culprit is foreign particles that contaminate the cells during manufacturing. Another possible cause is rough spots on the plates that damage the separator. Better manufacturing processes have reduced the 'infant mortality' rate significantly. Loss of Electrolyte
although sealed, the cells may lose some electrolyte during their life, especially if venting occurs due to excessive pressure during careless charging. Once venting has occurred, the spring-loaded vent seal on nickel-based cells may never properly close again, resulting in a build-up of white powder around the seal opening. The loss of electrolyte will eventually lower the battery capacity.
Permeation or loss of electrolyte in valve regulated lead-acid batteries (VRLA) is a recurring problem. Overcharging and operating at high temperatures are the causes. Replenishing lost liquid by adding water offers limited success. Although some capacity may be regained, the performance becomes unreliable. Cell matching
Quality cells are more consistent in capacity and age more evenly than the lower quality counterparts. Manufacturers of high-end power tools choose high quality cells because of durability under heavy load and temperature extremes. The extra cost pays back on longer lasting packs. INTROUCTION
In recent years there has been a growth in the use of cooking oils and fats for cooking of foods such as chicken, potatoes, pies, fish, etc. In the frying operation, large quantities of edible cooking oils or fats are heated in vats to temperatures in the order of 315°-375°, and the food is immersed in the oil or fat for cooking. During repeated use of the cooking oil or fat, the high temperatures cause the formation of free fatty acids (FFA). An increase in the FFA decreases the oil's smoke point and results in increasing smoke as the oil ages. In addition, when cooking; there is an oxidative degeneration of fats which results from contact of air with hot oil producing oxidized fatty acids (OFA). Heating transforms the OFA into secondary and tertiary by-products which may cause off-flavors and off-odors in the oil and fried food. Moreover, caramelization (which is a browning reaction which occurs when foods containing carbohydrates and proteins are exposed to heat) occurs during the use of the oil over a period of time, resulting in a very dark color of the oil which, combined with other by-products, produces dark, unappealing fried foods. Because of the tremendous cost resulting from the replacing of the cooking fats and oils after use thereof (normal useful life generally in the order of 2-10 days), the industry has searched for an effective and economical way to...
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