Thursday, July 16, 2009

Some common sense about Rechargeable battery

Some common sense about Rechargeable battery

What is the cycle life of rechargeable battery?

When a latitude D820 battery experiences a charge and discharge, we call a cycle or a period. In the stated charge and discharge principles and the capacity decline before a stated standard, the total cycles it can undergo called rechargeable battery cycle life.

What is rechargeable battery self discharge?

Primary Dell CF623 battery or full charged secondary battery, when put aside for a period, it is capacity will decline or lose, this phenomenon calls self discharge that is electricity flee away. It is decided by the inner electro-chemistry system, similar to water leakage from pond or reservoir.

What is battery inner impedance?

Battery impedance is the resistance when the current flow through an operating cell, in general the internal resistance is included both d.c. and a.c. resistance. For the rechargeable 40Y6795 battery cell resistance is small and electrode is easy to be polarized along with producing a polarization resistance while measure d.c. resistance, the accurate value can't be measured.

What is the memory effect?

Memory effect only happens on Ni-Cd batteries. As in traditional technology a Ni-Cd battery's negative is agglomeration with thick Ni crystal, if Ni-Cd batteries are recharged before they have been fully discharged, Ni crystal easily gathers to form agglomeration, which makes the primary discharge platform come into being. The HP HSTNN-LB31 battery stores the platform, which will be considered as the end of discharge for the next cycle even though the capacity decides that the battery can be discharged to a lower platform. The battery will store this process in its memory so during the next discharge, the battery only remembers this reduced capacity. Similarly any further incomplete discharge in each use will aggravate the effect makes lower capacity. The effect there are two methods to remove the effect: firstly deep discharge at trickle current (i.e. 0.1C to 0V), secondly several cycles at high currents (e.g. 1C).

What is the ambient temperature affects the battery performance?

Low temperatures (e.g. -15?) will obviously reduce Ni-Cd and Ni-MH Apple A1175 battery discharge rate. At -20? electrolyte is at its freezing point, charge speed will greatly slow down. At low temperature (under -15?) charge will raise the internal gas pressure and probably unseal the safety vent. Ambient temperature of 5?to 30? is the best range to get effective charge. Generally with temperature rising charge efficiency will become higher. But when the temperature rises to 45? or higher, the materials performance in the battery will be degenerated and battery service life will be shorten greatly.

What is the Over charge affects the battery performance?

The continual charge action after fully charged with certain charge approach is overcharge. the positive capacity is higher than the negative on design, the generated oxygen in positive can composite, through separator, with Cd generated in negative. In general condition the internal pressure will not rise obviously, but if the IBM thinkpad T43 battery charge current is so heavy or the charge time is so long, and the generated oxygen can not be used up in time, there will be some quality defect risen such as internal pressure rising, battery distortion, leakage and so on. Meanwhile its performance will decline.

What is the Over discharge affects the battery performance?

If a cell's voltage reaches a designed value, that means the battery has discharge the stored capacity, but still the discharge action is continual, over-discharge will cause. Commonly the end voltage can be identified through discharge current, for example the end voltage is set at Laptop battery 1.0V/cell as discharged at 0.2C-2C, and 0.8V/cell at 3C or more, e.g. 5C or 10C. Over discharge may cause disaster, especially at heavy current or repeated over discharge. Commonly over discharge can make cell inner pressure raise, and the reversibility of activity materials both in positive and negative will be damaged. Even by charge only part can recover and the capacity is reduced obviously.

What is the short circuit affects the battery performance?

Any kinds of conductive material being bridged with the external terminals of a battery will result in short circuit. Based on the Discount laptop batteries system, a short circuit may have serious consequences, e.g. rising electrolyte temperature or building up internal gas pressure. If the internal gas pressure value exceeds the limitation of cell cap endurances, the electrolyte will leak, which will damage battery greatly. If safe vent fails to respond, even explosion will occur. Therefore don't short circuit.

No comments:

Post a Comment