Some rechargeable batteries can be restored through external means,
ch 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 Acer Aspire One battery.
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 of Acer Aspire 4315 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.
Nickel-based batteries Acer Aspire One 10.1 inch battery exhibit a relatively high self-discharge. At ambient
temperature, a new nickel-cadmium loses about 10% of its capacity in the first
24 hours after charge. The self-discharge settles to about 10% per month afterwards.
Higher temperature increases the self-discharge substantially. As a general guideline,
the rate of self-discharge doubles with every 10°C (18°F) increase in
temperature. The self-discharge of nickel-metal-hydride is about 30% higher than
that of nickel-cadmium.
The self-discharge increases after a nickel-based
battery for Acer Aspire One 8.9 inch battery has been cycled for a few hundred times. The battery plates begin to swell
and press more firmly against the separator. Metallic dendrites, which are the
result of crystalline formation (memory), also increase the self-discharge by
marring the separator. Discard a nickel-based battery if the self-discharge reaches
30% in 24 hours.
The self-discharge of the lithium-ion battery is 5% in
the first 24 hours after charge, and then reduces to 1% to 2% per month thereafter.
The safety circuit adds about 3%. High cycle count and aging have little effect
on the self-discharge of lithium-based batteries.
A lead-acid Acer battery self-discharges
at only 5% per month or 50% per year. Repeated deep cycling increases self-discharge.
The percentage of self-discharge can be measured with a battery Acer Aspire 4520 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.
Cell matching
Even with modern manufacturing techniques, the cell capacities
cannot be accurately predicted, especially with nickel-based cells. As part of
manufacturing, each cell is measured and segregated into categories according
to their inherent capacity levels. The high capacity 'A' cells are commonly sold
for special applications at premium prices; the mid-range 'B' cells are used for
commercial and industrial applications; and the low-end 'C' cells are sold at
bargain prices. Cycling will not significantly improve the capacity of the low-end
cells. When purchasing rechargeable batteries Acer Aspire 4520G battery at a reduced price, the buyer should
be prepared to accept lower capacity levels.
The cells in a pack should
be matched within +/- 2.5%. Tighter tolerances are required on batteries DV6000 Battery with
high cell count, those delivering high load currents and packs operating at cold
temperatures. If only slightly off, the cells in a new pack will adapt to each
other after a few charge/discharge cycles. There is a correlation between well-balanced
cells and battery longevity.
Why is cell matching so important? A weak
cell holds less capacity and is discharged more quickly than the strong one. This
imbalance may cause cell reversal on the weak cell if discharged too low. On charge,
the weak cell is ready first and goes into heat-generating overcharge while the
stronger cell still accepts charge and remains cool. In both cases, the weak cell
is at a disadvantage, making it even weaker and contributing DV2000 Battery to a more acute cell
mismatch.
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.
lithium-based
cells are by nature closely matched when they come off the manufacturing line.
Tight tolerances are important because all cells in a pack must reach the full-charge
and end-of-discharge HP Pavilion dv8000 Battery voltage thresholds at a unified time. A built-in protection
circuit safeguards against cells that do not follow a normal voltage pattern.
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 for Pavilion DV5000 Battery.Another possible cause is rough spots on the plates that damage the separator.
Better manufacturing processes have reduced the 'infant mortality' rate significantly.
Cell reversal caused by deep discharging also contributes to shorted cells.
This may occur if a nickel-based vgp-bps8 battery is being fully depleted under a heavy
load. nickel-cadmium is designed with some reverse voltage protection. A high
reverse current, however, will produce a permanent electrical short. Another contributor
is marring of the separator through uncontrolled crystalline formation, also known
as memory.
Applying momentary high-current bursts in an attempt to repair
shorted cells offers limited success. The short may temporarily evaporate but
the damage to the separator material remains. The repaired cell often exhibits
a high self-discharge and the short frequently returns. vgp-bps9/b Replacing a shorted cell
in an aging pack is not recommended unless the new cell is matched with the others
in terms of voltage and capacity.
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 vgp-bps9a/b battery capacity.
Permeation, or loss of electrol yte 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. vgp-bps12
If correctly charged, lithium-ion cellson should never generate gases and cause
venting. But in spite of what is said, the lithium-based cells can build up internal
pressure under certain conditions. Some cells include an electrical switch sony battery that
disconnects the current flow if the cell pressure reaches a critical level. Other
cells rupture a membrane to release the gases in a controlled way. lithium-ion-polymer
in a pouch cell sometime grows to the shape of a small balloon because these cells
do not include venting. Ballooning cell are known to damage the housing of the
portable device.
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