2011年9月16日星期五
2011年9月15日星期四
2011年9月14日星期三
VRLA Battery Failure Modes
About 60% of VRLA batteries fail due to grid corrosion. As explained in our article titled: Lead Acid Battery Basics, battery charging, including float charging, is associated with water electrolysis which decomposes water into Hydrogen and Oxygen created at the positive plate. The valves in VRLA battery do not enable gasses venting into air, and most are recombined by a diffusion process to form water again. Still, corrosion due to oxidation of the grid on positive plates is unavoidable. The corrosion gradually reduces the amount of active material causing eventually total battery failure.
The corrosion process depends on the ratio of plate's surface area to weight. A thin, plate has larger surface area to grid weight, compared to thick plates containing a few thin wires. Hence,
thin grid has faster rate of corrosion per AH capacity. Therefore, UPS batteries, for short back up times, which need large area to provide the high currents, have low 3 to 5 years longevity. Whereas, UPS systems for longer back up times, such as used also in communication, use VRLA batteries with less plates but thick grids; which have higher lifetime, of up to 15 years.
Battery dry out, a term used to describe battery failure due to loss of electrolyte is the second main reason for battery malfunction, comprising more than 30% of battery failures. Presence of active material in the required quantity is mandatory to maintain battery capacity. Therefore Loss of electrolyte affects dramatically Battery's ability to continue providing power.
Overcharging is the main reason causing dry out failure. Normally recombination of Oxygen and Hydrogen gasses, replenishes almost full amount of water extracted from the acid by electrolysis reaction. However, even a small charging or float over voltage, above the correct voltage setting, or high rate of charging current, can produce oxygen and hydrogen at a higher rate compared to the rate of recombination reaction. Thus, increasing the gas pressure in the battery, until the pressure relief valves open.
In VRLA batteries the electrolyte lost in the air through the valves due to overcharge, cannot be replaced, resulting in reduced battery capacity. Certain additional reactions, such as corrosion, contribute also to battery dry out by converting electrolyte in the battery to non active constituents.
As indicated above, 90 % of battery failures affecting battery longevity are caused by grid corrosion and battery dry out. Additional reasons, generally responsible to about 10% of total battery failures, most also caused due to grid corrosion or dry out, comprise of: cell shorting, cell opening, leakage, undercharge, poor internal or external interconnections, cell reversal and
thermal runaway.
If you want to know more about VRLA battery, you can just visit Leoch International, which is an excellent manufacturer of lead acid batteries. The company is a public company which has over 10 year’s history and it is very reliable and dependable. If you are interested in the company, you can search for more information in the internet. The office website is http://www.leoch.com.
2011年9月13日星期二
2011年9月12日星期一
Improper Charge affects the performance of lead acid battery
Some said, "Lead acid battery getting dead is not for using but charging." This thought seems to be correct in some ways. The charging performance of lead acid battery is very important for its lifespan and usability. Hence we must pay attention to the charging methods. According to most of consumers, the optimal way is to charge the battery when it is discharged for 50%-70%, which can make the life reach the maximum efficiency.
Meanwhile, temperature also has influence on charging. Lead acid battery will be over charged in the high temperature. We should reduce the temperature to enable to have a good heat dissipation. Avoid charging the battery after it is under the blazing sun for quite a long time. The sunshine will make the battery temperature increase and all kinds of active materials more activity to affect the lifespan. On the contrary, in the low temperature condition, the charging reception of lead acid battery will be poor and it will always be not fully charged. At this moment, we must enhance the charging voltage and extend the charging time, meanwhile we should take heat preservation and anti-freeze measures to ensure it has a fully charging, then prolong the service lifespan.
If you want to know more about lead acid battery, you can just visit Leoch International, which is an excellent manufacturer of lead acid batteries. The company is a public company which has over 10 year’s history and it is very reliable and dependable. If you are interested in the company, you can search for more information in the internet. The office website is http://www.leoch.com.
2011年9月7日星期三
Check if automobile battery is dead
No matter how well your cars are working, if the battery dies and can't be recharged, you can still not move any more. An automobile battery usually has a sticker on it that shows when you bought it and how long you can expect it to survive. To prevent being stuck on the road with a dead battery, you have to replace the battery before it comes to the end of its life expectancy. There are some steps to help you to judge if the automobile battery needs to be replaced.
First, though, it's a good idea to see if your battery needs to be replaced or if it simply could use a good cleaning. Sulfate, created over time by the battery's discharge of lead, can build up on the terminals as a cakey white substance that prevents the battery from recharging during use. You can get rid of this sulfate with a simple solution of baking soda and water. Be sure the car is off by removing the keys from the ignition and brush the solution onto the sulfate to loosen the deposit. After the terminals are clean, try the ignition. If the car starts up, it should be able to recharge itself and you may not need a replacement after all.
If your automobile battery is fully dead, consider having a professional do the job for you. Batteries can be heavy: The average car battery contains more than 24 pounds (10.8 kilograms) of lead, not including the rest of the components. Most auto parts stores offer free battery installation when you purchase a new one from them.
At this point, you've decided your battery must be replaced and that you're going to handle it yourself. Good for you.
Of course, if you want to know more about information about batteries, you can visit my private blog, Leoch Battery Blog.
2011年9月6日星期二
2011年9月2日星期五
Lead Acid Battery Charging (1) - Floating Charge
There are three charging methods of lead acid battery: floating charge, equalizing charge, cycle charge. This article will tell you charge parameters and announcements of floating charge.
Charge Parameters:
Voltage: 2.23-2.30V/cell (25℃) (recommendation for 2.25V/cell)
Largest charging current: 0.30C10
Temperature compensation coefficient: -2mV/℃-cell (base on 25℃)
Range of charging voltage: +-0.02V/cell
Notes:
1. During the initial stage, there are some differences about voltage among each cell, but after half a year, they will be in accordance.
2. So high or low voltage of floating charge will have influence on lead acid batteries. If the voltage is higher for long time or batteries are over charged, it will shorten the lifespan. If it is lower, or not enough, it will cause the voltage not in accordance and make the capacity of battery pack go down, then shorten the life.
If you want to know more about lead acid battery, you can just visit Leoch International, which is an excellent manufacturer of lead acid battery. The company is a public company which has over 10 year’s history and it is very reliable and dependable. If you are interested in the company, you can search for more information in the internet. The office website is http://www.leoch.com.
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