Memory effect, often known as battery effect, lazy battery impact, Memory Wave or battery memory, is an impact observed in nickel-cadmium rechargeable batteries that causes them to carry less cost. It describes the state of affairs through which nickel-cadmium batteries progressively lose their most energy capacity if they're repeatedly recharged after being solely partially discharged. The battery appears to "remember" the smaller capacity. The term "memory" came from an aerospace nickel-cadmium software through which the cells had been repeatedly discharged to 25% of accessible capability (give or take 1%) by exacting pc control, then recharged to 100% capability without overcharge. This lengthy-time period, repetitive cycle régime, with no provision for overcharge, resulted in a lack of capability beyond the 25% discharge point. True memory-effect is specific to sintered-plate nickel-cadmium cells, and is exceedingly troublesome to reproduce, particularly in decrease ampere-hour cells. In a single specific take a look at program designed to induce the impact, none was discovered after more than seven hundred exactly-controlled charge/discharge cycles.

In the program, spirally-wound one-ampere-hour cells had been used. In a follow-up program, 20-ampere-hour aerospace-sort cells had been used on the same take a look at régime; memory results had been observed after just a few hundred cycles. Phenomena which are not true memory results may occur in battery varieties aside from sintered-plate nickel-cadmium cells. In particular, lithium-based cells, not normally topic to the memory effect, could change their voltage levels in order that a digital lower of capacity could also be perceived by the battery management system. A standard course of often ascribed to memory impact is voltage depression. On this case, the output voltage of the battery drops extra rapidly than normal as it's used, despite the fact that the whole capability stays virtually the identical. In fashionable digital equipment that screens the voltage to indicate battery cost, the battery appears to be draining in a short time. To the person, it appears the battery just isn't holding its full cost, which seems similar to memory effect.

This is a typical problem with excessive-load units equivalent to digital cameras and cell telephones. Voltage depression is attributable to repeated over-charging of a battery, which causes the formation of small crystals of electrolyte on the plates. These can clog the plates, growing resistance and decreasing the voltage of some individual cells within the battery. This causes the battery as a whole to appear to discharge quickly as those particular person cells discharge rapidly and the voltage of the battery as a complete abruptly falls. The effect could be overcome by subjecting every cell of the battery to one or more deep cost/discharge cycles. This should be finished to the person cells, not a multi-cell battery; in a battery, some cells may discharge earlier than others, resulting in those cells being subjected to a reverse charging current by the remaining cells, doubtlessly resulting in irreversible injury. High temperatures can even scale back the charged voltage and the charge accepted by the cells.

Some rechargeable batteries might be damaged by repeated deep discharge. Batteries are composed of multiple comparable, but not identical, cells. Each cell has its personal cost capacity. Because the battery as an entire is being deeply discharged, the cell with the smallest capability could reach zero charge and will "reverse cost" as the other cells continue to force present by way of it. The ensuing loss of capability is often ascribed to the memory impact. Battery users may try to avoid the memory impact proper by fully discharging their battery packs. This observe is more likely to cause extra injury as one of the cells will likely be deep discharged. The harm is focused on the weakest cell, so that each extra full discharge will trigger increasingly more damage to that cell. Repeated deep discharges can exacerbate the degradation of the weakest cell, leading to an imbalance in the battery pack, where the affected cell turns into a limiting consider total efficiency. Over time, this imbalance can result in decreased capability, shorter run times, and the potential for overcharging or overheating of the other cells, further compromising the battery's safety and longevity.

All rechargeable batteries have a finite lifespan and boost brain function can slowly lose storage capability as they age resulting from secondary chemical reactions within the battery whether or not it is used or not. Some cells may fail sooner than others, however the effect is to cut back the voltage of the battery. Lithium-based batteries have one of many longest idle lives of any development. Unfortunately the number of operational cycles remains to be fairly low at approximately 400-1200 full charge/discharge cycles. The lifetime of lithium batteries decreases at higher temperature and states of charge (SoC), whether used or boost brain function not; most life of lithium cells when not in use(storage) is achieved by refrigerating (without freezing) charged to 30%-50% SoC. To prevent overdischarge, battery should be introduced back to room temperature and recharged to 50% SoC once every six months or as soon as per year. Bergveld, H.J.; Kruijt, W.S.; Notten, Peter H. L. (2002-09-30). Battery Management Systems: Design by Modelling. Linden, David; Reddy, Thomas B. (2002). Handbook Of Batteries (third ed.). New York: Memory Wave McGraw-Hill. p.

• 글쓰기

• 수정
• 삭제
• 목록