It's Monday and you're late for work thanks to the sudden death of your alarm clock's batteries--the same ones you replaced not too long ago. Yet while they only lasted a few weeks, the hp batteries in your remote control have thrived for over a year. So what's the difference between them? Is it the brand? Do more expensive batteries really last longer? And why do some batteries, even when they're the same brand, last longer than others?
When you insert batteries into a device, they have to be positioned in the battery compartment with the positive and negative sides, or terminals, facing a certain way. When properly inserted, the terminals then line up with a wire spring inside the device. This wire acts as a bridge between the two terminals, allowing electrons to flow from the hp pavilion dv8000 battery into the wire, thereby charging the device and enabling it to function.
Batteries have a very long shelf life, typically lasting a year or more without losing power. Chances are, if a store is selling it, it has not yet expired and will work the same regardless of whether it's purchased a day or a year before its expiration date. So you really shouldn't have to be too concerned with the age of a hp 484784-001 battery and don't need to look for the pack with the latest expiration date stamped on it. However, even if they aren't ever activated, batteries can lose up to 20 percent of their original power per year if they're kept in a warm area (about 68 to 86 degrees F). Known as the battery's self discharge rate, this loss of power can be reduced if batteries are stored at lower temperatures. On the same token, however, extremely low temperatures can also reduce a hp compaq nc6000 battery's charge. So while it may help to store your batteries in a refrigerator, the freezer isn't such a great idea.
Assuming you already store your batteries at an appropriate temperature, what else determines whether or not they last a week, a month or a year? Well, contrary to what those commercials may state, it's really more about the type of the hp compaq 6910p battery rather than the brand. An AAA battery, for example, will last longer than a D battery. In addition, a battery's life is greatly influenced by the product in which it is used and the amount of energy required to make the device work. Although most products like CD players and clocks tend to use less energy, others such as MP3 players and cameras typically require more energy. Lithium, titanium and premium alkaline batteries are designed for these high-energy devices, whereas regular alkaline batteries work best with low-energy devices. In terms of brands, countless studies have been done with independent testing from companies like TechTV and Zbattery.com, but there has been no conclusive proof that any particular brand works better than any other. Rather, the factors that determine how long hp compaq 6710b battery is based on how they're stored and how they're used.
Monday, 23 May 2011
Monday, 9 May 2011
Heat, Loading and Battery Life
Heat is a killer of all batteries and high temperatures cannot always be avoided. This is the case with a apple computerbattery inside a laptop, a starter battery under the hood of a car and stationary batteries in a tin shelter under the hot sun. As a guideline, each 8°C (15°F) rise in temperature cuts the life of a sealed lead acid battery in half. A VRLA batteryfor stationary applications that would last 10 years at 25°C (77°F) would only live for five years if operated at 33°C (95°F). Once the battery is damaged by heat, the capacity cannot be restored. The life of a battery also depends on the activity and is shortened if the battery is stressed with frequent discharge.
According to the 2010 BCI Failure Mode Study, starter batteries have become more heat-resistant over the past 10 years. In the 2000 study, a change of 7°C (12°F) affected battery life by roughly one year; in 2010 the heat tolerance has widened to 12°C (22°F). In 1962, a starter battery lasted 34 months, and in 2000 the life expectancy had increased to 41 months. In 2010, BCI reports an average age of 55 months of use. The cooler North attains 59 months and the warmer South 47 months.
Cranking the engine poses minimal stress on a starter apple a1175 battery. This changes in a start-stop function of a micro hybrid. The micro hybrid turns the IC engine off at a red traffic light and restarts it when the traffic flows. This results in about 2,000 micro cycles per year. Data obtained from car manufacturers show a capacity drop to about 60 percent after two years of use in this configuration. To solve the problem, automakers are using specialty AGM and other variations that are more robust than the regular lead acid. Read more about Alternate Battery Systems. Figure 5 shows the drop in capacity after 700 micro cycles. The simulated start-stop test was performed in Cadex laboratories. CCA remains high.
Test method: The test battery was fully charged and then discharged to 70 percent to resemble the SoC of a micro hybrid in real life. The battery was then discharged at 25A for 40 seconds to simulate engine off condition at stoplight with the headlight on, before cranking the engine at 400A and recharging. The CCA readings were taken with the Spectro CA-12.
The cell voltages on a apple a1185 battery string must be similar, and this is especially important for higher-voltage VRLA batteries. With time, individual cells fall out of line, and applying an equalizing charge every six months or so should theoretically bring the cells back to similar voltage levels. While equalizing will boost the needy cells, the healthy cell get stressed if the equalizing charge is applied carelessly. What makes this service so difficult is the inability to accurately measure the condition of each cell and provide the right dose of remedy. Gel and AGM batteries have lower overcharge acceptance than the flooded version and different equalizing conditions apply. Always refer to the manufacturer’s specifications.
Water permeation, or loss of electrolyte, is a concern with sealed lead acid batteries, and overcharging contributes to this condition. While flooded systems accept water, a fill-up is not possible with VRLA. Adding water has been tried, but this does not offer a reliable fix. Experimenting with watering turns the VRLA into unreliable battery that needs high maintenance.
Flooded lead acid batteries are one of the most reliable systems. With good maintenance these batteries last up to 20 years. The disadvantages are the need for watering and providing good ventilation. When VRLA was introduced in the 1980s, manufacturers claimed similar life expectancy to flooded systems, and the telecom industry switched to these maintenance-free batteries. By mid 1990 it became apparent that the life for VRLA did not replicate that of a flooded type; the useful service life was limited to only 5–10 years. It was furthermore noticed that exposing the batteries to temperatures above 40°C (104°F) could cause a thermal runaway condition due to dry-out.
A new lead acid battery should have an open circuit voltage of 2.125V/cell. At this time, the apple powerbook g4 12 battery is fully charged. During buyer acceptance, the lead acid may drop to between 2.120V and 2.125V/cell. Shipping, dealer storage and installation will decrease the voltage further but the battery should never go much below 2.10V/cell. This would cause sulfation. Battery type, applying a charge or discharge within 24 hours before taking a voltage measurement, as well as temperature will affect the voltage reading. A lower temperature raises the OCV; warm ambient lowers it.
According to the 2010 BCI Failure Mode Study, starter batteries have become more heat-resistant over the past 10 years. In the 2000 study, a change of 7°C (12°F) affected battery life by roughly one year; in 2010 the heat tolerance has widened to 12°C (22°F). In 1962, a starter battery lasted 34 months, and in 2000 the life expectancy had increased to 41 months. In 2010, BCI reports an average age of 55 months of use. The cooler North attains 59 months and the warmer South 47 months.
Cranking the engine poses minimal stress on a starter apple a1175 battery. This changes in a start-stop function of a micro hybrid. The micro hybrid turns the IC engine off at a red traffic light and restarts it when the traffic flows. This results in about 2,000 micro cycles per year. Data obtained from car manufacturers show a capacity drop to about 60 percent after two years of use in this configuration. To solve the problem, automakers are using specialty AGM and other variations that are more robust than the regular lead acid. Read more about Alternate Battery Systems. Figure 5 shows the drop in capacity after 700 micro cycles. The simulated start-stop test was performed in Cadex laboratories. CCA remains high.
 | Figure 5: Capacity drop of a flooded starter battery when micro cycling Start-stop function on a micro hybrid stresses the battery; the capacity drops to about 50 percent after two years of use. AGM is more robust for this application. Courtesy of Cadex, 2010 |
The cell voltages on a apple a1185 battery string must be similar, and this is especially important for higher-voltage VRLA batteries. With time, individual cells fall out of line, and applying an equalizing charge every six months or so should theoretically bring the cells back to similar voltage levels. While equalizing will boost the needy cells, the healthy cell get stressed if the equalizing charge is applied carelessly. What makes this service so difficult is the inability to accurately measure the condition of each cell and provide the right dose of remedy. Gel and AGM batteries have lower overcharge acceptance than the flooded version and different equalizing conditions apply. Always refer to the manufacturer’s specifications.
Water permeation, or loss of electrolyte, is a concern with sealed lead acid batteries, and overcharging contributes to this condition. While flooded systems accept water, a fill-up is not possible with VRLA. Adding water has been tried, but this does not offer a reliable fix. Experimenting with watering turns the VRLA into unreliable battery that needs high maintenance.
Flooded lead acid batteries are one of the most reliable systems. With good maintenance these batteries last up to 20 years. The disadvantages are the need for watering and providing good ventilation. When VRLA was introduced in the 1980s, manufacturers claimed similar life expectancy to flooded systems, and the telecom industry switched to these maintenance-free batteries. By mid 1990 it became apparent that the life for VRLA did not replicate that of a flooded type; the useful service life was limited to only 5–10 years. It was furthermore noticed that exposing the batteries to temperatures above 40°C (104°F) could cause a thermal runaway condition due to dry-out.
A new lead acid battery should have an open circuit voltage of 2.125V/cell. At this time, the apple powerbook g4 12 battery is fully charged. During buyer acceptance, the lead acid may drop to between 2.120V and 2.125V/cell. Shipping, dealer storage and installation will decrease the voltage further but the battery should never go much below 2.10V/cell. This would cause sulfation. Battery type, applying a charge or discharge within 24 hours before taking a voltage measurement, as well as temperature will affect the voltage reading. A lower temperature raises the OCV; warm ambient lowers it.
Tuesday, 3 May 2011
Battery Definitions
Batteries come in all shapes and sizes and there could be as many types as there are species of dog. Rather than giving batteries unique names as we do with pets, we distinguish batteries by chemistry, voltage, size, specific energy (capacity), specific power, (delivery of power) and more. A battery can operate as a single cell to power a cellular phone, or be connected in series to deliver several hundred volts to serve a UPS (uninterruptible power supply system) and the electric powertrain of a vehicle. Some batteries have high capacity but cannot deliver much power, while a starter battery has a relatively low capacity but can crank the engine with 300A.
The largest battery systems are used for grid storage to store and delivery energy derived from renewable power sources such as wind turbines and solar systems. A 30-megawatt (MW) wind farm uses a storage battery of about 15MW. This is the equivalent of 20,000 starter batteries and costs about $10 million. One mega-watt feeds 50 houses or a super Walmart store. Let’s now examine each of the hp pavilion dv6 battery characteristics further.
Chemistry
The most common chemistries are lead, nickel and lithium. Each system requires its own charging algorithm. Unless provisions are made to change the charge setting, different battery chemistries cannot be interchanged in the same charger. Also observe the chemistry when shipping and disposing of batteries; each type has a different regulatory requirement.
Voltage
Voltage describes the nominal open circuit voltage (OCV), which varies with chemistry and number of cells connected in series. Always observe the correct voltage when connecting to a load or a charger. Do not proceed if the voltage does not agree.
Capacity
Capacity represents the specific energy in ampere-hours (Ah). Manufacturers often overrate a hp pavilion dv7 battery by giving a higher Ah rating than it can provide. You can use a battery with different Ah (but correct voltage), provided the rating is high enough. Chargers have some tolerance to batteries with different Ah ratings. A larger battery will take longer to charge than a small one.
Cold cranking amps (CCA)
CCA specifies the ability to draw high load current at –18°C (0°F) on starter batteries. Different norms specify dissimilar load durations and end voltages.
Specific energy and energy density
Specific energy orgravimetric energy density defines the battery capacity in weight (Wh/kg); energy density or volumetric energy density is given in size (Wh/l). A battery can have a high specific energy but poor specific power (load capability), as is the case in an alkaline battery. Alternatively, a battery may have a low specific energy but can deliver high specific power, as is possible with the supercapacitor. Specific energy is synonymous with battery capacity and runtime.
Specific power
Specific power or gravimetric power density indicates the loading capability, or the amount of current the hp pavilion dv8 battery can provide. Batteries for power tools exhibit high specific power but have reduced specific energy (capacity). Specific power is synonymous with low internal resistance and the delivery of power.
C-rates
C-rates specify charge and discharge currents. At 1C, the battery charges and discharges at a current that is par with the marked Ah rating; at 0.5C the current is half, and at 0.1C it is one tenth. On charge, 1C charges a good battery in about one hour; 0.5C takes 2 hours and 0.1C 10 to 14 hours. Read more about What is the C-rate?
Load
Also known as electromotive force (EMF), the load draws energy from the battery. Internal hp battery resistance and depleting state-of-charge cause the voltage to drop.
Watts and Volt-amps (VA)
Power drawn from a battery is expressed in watts (W) or volt-amps (VA). Watt is the real power that is being metered; VA is the apparent power that determines the wiring sizing and the circuit breakers. On a purely resistive load, watt and VA readings are alike; a reactive load such as an inductive motor or florescent light causes a drop in the power factor (pf) from the ideal one (1) to 0.7 or lower. For example, a pf of 0.7 has a power efficiency of 70.
The largest battery systems are used for grid storage to store and delivery energy derived from renewable power sources such as wind turbines and solar systems. A 30-megawatt (MW) wind farm uses a storage battery of about 15MW. This is the equivalent of 20,000 starter batteries and costs about $10 million. One mega-watt feeds 50 houses or a super Walmart store. Let’s now examine each of the hp pavilion dv6 battery characteristics further.
Chemistry
The most common chemistries are lead, nickel and lithium. Each system requires its own charging algorithm. Unless provisions are made to change the charge setting, different battery chemistries cannot be interchanged in the same charger. Also observe the chemistry when shipping and disposing of batteries; each type has a different regulatory requirement.
Voltage
Voltage describes the nominal open circuit voltage (OCV), which varies with chemistry and number of cells connected in series. Always observe the correct voltage when connecting to a load or a charger. Do not proceed if the voltage does not agree.
Capacity
Capacity represents the specific energy in ampere-hours (Ah). Manufacturers often overrate a hp pavilion dv7 battery by giving a higher Ah rating than it can provide. You can use a battery with different Ah (but correct voltage), provided the rating is high enough. Chargers have some tolerance to batteries with different Ah ratings. A larger battery will take longer to charge than a small one.
Cold cranking amps (CCA)
CCA specifies the ability to draw high load current at –18°C (0°F) on starter batteries. Different norms specify dissimilar load durations and end voltages.
Specific energy and energy density
Specific energy orgravimetric energy density defines the battery capacity in weight (Wh/kg); energy density or volumetric energy density is given in size (Wh/l). A battery can have a high specific energy but poor specific power (load capability), as is the case in an alkaline battery. Alternatively, a battery may have a low specific energy but can deliver high specific power, as is possible with the supercapacitor. Specific energy is synonymous with battery capacity and runtime.
Specific power
Specific power or gravimetric power density indicates the loading capability, or the amount of current the hp pavilion dv8 battery can provide. Batteries for power tools exhibit high specific power but have reduced specific energy (capacity). Specific power is synonymous with low internal resistance and the delivery of power.
C-rates
C-rates specify charge and discharge currents. At 1C, the battery charges and discharges at a current that is par with the marked Ah rating; at 0.5C the current is half, and at 0.1C it is one tenth. On charge, 1C charges a good battery in about one hour; 0.5C takes 2 hours and 0.1C 10 to 14 hours. Read more about What is the C-rate?
Load
Also known as electromotive force (EMF), the load draws energy from the battery. Internal hp battery resistance and depleting state-of-charge cause the voltage to drop.
Watts and Volt-amps (VA)
Power drawn from a battery is expressed in watts (W) or volt-amps (VA). Watt is the real power that is being metered; VA is the apparent power that determines the wiring sizing and the circuit breakers. On a purely resistive load, watt and VA readings are alike; a reactive load such as an inductive motor or florescent light causes a drop in the power factor (pf) from the ideal one (1) to 0.7 or lower. For example, a pf of 0.7 has a power efficiency of 70.
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