Battery Care & Frequently Asked Questions
It is very important to prepare your new batteries for service. This is the most misunderstood procedure for placing new batteries into service. The most common mistake is the mis-use of your rapid charger on a new battery. The charger will tell you the battery is charged after only 60 to 90 minutes. However you must ignore the ready light on the first initial charge. Any new NiCad, NiMh or Li Ion battery needs to be charged at least 14 to 16 hours. If you do not do this, your new battery will immediately have a short memory effect from that first short charge.
Overcharging a battery occurs when the total capacity drained has been replaced by recharging, but the battery remains on charge. Overcharging creates excessive heat which can cause the battery plates within the cells to buckle and shed their active material. A battery will react to the overcharge by producing an excessive amount of hydrogen and oxygen. These gases are the result of the breakdown of the water molecules within the electrolyte. The water that has been displaced by overcharging can be replaced in a wet (non-sealed) battery, but, in maintenance-free sealed lead batteries, NiCad, NiMH permanent capacity loss will result. A good charger has built in circuitry that senses the battery state and converts to a lower trickle charge so as not to over heat the battery. Excessive discharging can also damage a battery. The amount of discharge a battery can have without damage depends upon the chemistry of the battery. In general, a lead acid battery will can not tolerate as deep a discharge as a NiCad battery or NiMH battery. Sealed lead acid batteries function best if they are discharged to only about 85% of nominal voltage (10.2V on 12V battery). NiCad & NiMH are good for two way adios because they can be deeply discharged and recharged.
Sulfation is the formation or deposit (on lead-acid-batteries) of lead sulfate on the surface and in the pores of the active material of the battery lead plates. If the sulfation becomes excessive and forms large crystals on the plates, the battery will not operate efficiently and may not work at all. Common causes of battery sulfation are standing a long time in a discharged condition, operating at excessive temperatures, and prolonged under or over charging.
Battery cycle: is the cycle of a battery at a discharge plus a recharge. For example, if your battery is fully charged. As you use the battery it discharges. Then it is recharged to full charge. That is one cycle. Cycle life is the total number of cycles a battery can yield. The cycle life is very important in battery applications. A NiCad battery has a cycle life of approximately 1000 cycles. NiMH has a shorter (about 700) cycle life than NiCad.
Deep-cycle batteries typically feature thick plates with a high-density active material. The thick battery plates allow for reserve energy to be stored deep within the battery plate and released during slow discharge such as electronic instrument use. The high-density active material remains within the battery plate/grid structure longer, resisting the normal degradation found in cycling conditions. They are typically used where the battery is discharged to great extent and then recharged. For example, sealed lead batteries.
One common battery rating is Amp-Hour (ah): Amp-hour rating for battery capacity is calculated by multiplying the current (in amperes) by time (hours) the current is drawn. Amp-hour battery rating is commonly used on sealed lead acid batteries. For example: A battery which delivers 2 amperes for 20 hours would have a 40 amp-hour battery rating (2 x 20= 40). Smaller batteries such as two way radio NiCad or NiMH are rated in mili-amp hours (mAh).
Cold Cranking Amperage battery rating: CCA is the discharge load in amps which a battery can sustain for 30 seconds at 0 degrees F. and not fall below 1.2 volts per cell (i.e. 7.2volts for a 12V battery). This battery rating measures a burst of energy that a car needs to start on a cold morning. This rating is used mainly for rating batteries for engine starting capacity and does not apply to NiCad batteries, NiMH batteries or Alkaline batteries.
Reserve capacity battery rating: RC is the number of minutes a new, fully charged battery at 80 degrees F. will sustain a discharge load of 25 amps to a cut-off voltage of 1.75 volts per cell (i.e. 10.5volts for a 12V battery). This battery rating measures more of a continuous load on the battery.
Note: When interconnecting batteries (cells) they must be the same type batteries (cells)
Batteries may be connected in series. The positive terminal of the first battery is connected to the negative terminal of the second battery, the positive terminal of the second is connected to the negative of the third, etc. The voltage of the assembled battery is the sum of the battery voltages of the individual cells. The capacity of the battery is unchanged.
Batteries may be connected in parallel. The positive terminal of the first battery is connected to the positive terminal of the second battery, the positive terminal of the second is connected to the positive of the third, etc. and The negative terminal of the first battery is connected to the negative terminal of the second battery, the negative terminal of the second is connected to the negative of the third, etc. In this configuration, the capacity increases. The sum of each cell's capacity is added to each other. The battery pack voltage is unchanged.
Example, if you take 5- 6volt / 10ah batteries and connect the batteries in series. You would end up with a battery pack that is 30 Volts and 10AH. If you connect the batteries in parallel, you would end up with a battery pack that is 6 Volts and 50ah. This is how an ordinary auto battery is made. 6- 2volt cells are put in series to make a 12v battery. The 6 cells are just enclosed in one case. Most battery packs are done the same way.
A few types of batteries are: Sealed Lead Acid, Flooded Lead Acid, NiCad, NiMH, Alkaline, Silver Oxide, Lithium, Mercury(not mfg. in US any more), Manganese-Dioxide, Zinc-Air.
NiCad (Nickel Cadmium) & NiMH (Nickel Metal Hydride) Batteries:
Nickel Cadmium and Nickel Metal Hydride batteries by nature need to be "deep cycled" (fully discharged) before being placed back in their charger. Deep cycling your battery will help your NiCad battery maintain its maximum performance.
The NiMH and Li-ion chemistries are most severely affected by hot storage and operation. Among the Li-ion family, the cobalt has an advantage over the manganese (spinel) in terms of storage at elevated temperatures.
Always "initialize" brand new batteries. To initialize, let your battery stay in the charger approximately 50% (we say at least 14 to 16 hours) longer than a normal charge. Only perform initialization on the first Charge. Wait until your equipment signals "low battery" before placing the battery back into it's charger. Failure to "deep cycle" NiCd batteries will result in "memory" buildup. Memory will reduce the amount of energy you can draw each time you use the battery. It will also shorten your battery's overall cycle life. Never leave your battery in it's charger longer than the recommended charging time. Newer chargers have indicator lights which signal charging has completed and revert to a trickle charge when full charge is reached. To prevent memory buildup, immediately remove the battery when the charge cycle is finished. NiCd batteries can be stored up to two years without suffering from significant cycle loss. If you plan to store your batteries for an extended period, it is recommended to recharge your batteries every 90 days.
The RECHARGEABLE Li-ion battery does not like prolonged storage. Irreversible capacity loss occurs after 6 to 12 months, especially if the battery is stored at full charge and at warm temperatures. It is often necessary to keep a battery fully charged as in the case of emergency response, public safety and defense. Running a laptop (or other portable device) continuously on an external power source with the battery engaged will have the same effect. The combination of a full charge condition and high temperature cannot always be avoided. Such is the case when keeping a spare battery in the car for a mobile phone.
THE CHARGING METHOD FOR SLA BATTERIES IS THE OPPOSITE CONCEPT FROM NiCad & NiMH BATTERIES. IT CAN'T HURT TO RECHARGE A PARTIALLY DISCHARGED SLA BATTERY. Lead Acid batteries by nature need to be constantly charged. If a lead acid battery becomes fully discharged, it is imperative that it be given a full charge immediately. This will prevent internal "sulfation" from occurring which is a condition that will permanently destroy your battery. Gel or sealed lead acid batteries are basically the same chemistry as a wet (flooded cell) battery. The batteries' electrolyte is in a gelatin form and is absorbed into the plates and the battery is sealed with epoxies. These batteries may be used in any position and the batteries are exceptionally leak resistant. Battery uses are for back up power supply, emergency lights, and alarm panels. These batteries are made up of 2 volts per cell. So the most common SLA batteries are 2, 4, 6, and 12 volt.
Do Not store an SLA battery below freezing temperatures. Once a pack has been frozen, it will be permanently damaged and its service life will be drastically reduced. A previously frozen battery will only be able to deliver a limited number of cycles.
Always keep lead acid batteries fully charged. If your battery serves as a backup energy source, be sure your equipment is always plugged in. So that a constant trickle charge is on. Store lead acid batteries in a cool, dry location. Never store your batteries on ground, metal or cement surfaces. If stored for more than 90 days, give your batteries a full charge. Warmer temperatures adversely affect shelf life and the need for recharging. Charge SLA batteries after each use, no matter how short the usage. Remember it is good to do a Top-Off charge for SLA batteries. Do not over stock your SLA batteries. It is better to buy smaller quantities that will be put into service within 90 days.
Four major factors that affect battery life (both sealed and flooded cells):
Ambient temperature Battery chemistry Cycling Maintenance and service Ambient Temperature The rated output capacity of a battery is based on an ambient temperature of 25C (77F). It is important to realize that any variation from this operating temperature can alter the performance of the battery, and shorten its expected life. High temperature reduces the battery life greatly. A rule of thumb when determining battery life in relation to temperature is: that for every 8.3 degreesC (15F) above the average annual temperature (that being 25 degreesC (77F), then the life of the battery will be reduced by 50 percent.
Battery capacity is determined by the battery's ability to convert chemical energy into electrical current at a specified rate for a specified amount of time.
No battery will last forever-- even one that experiences minimal use. This is because sealed lead acid batteries are Electro-chemical devices whose ability to store and deliver power slowly decreases over time. Even if you follow all the guidelines for proper storage temperature and maintenance, you still must replace them after a certain period of time.
Cycling During a utility power failure (severe brownout or blackout conditions), back up equipment operates on battery power. Once utility power is restored, the battery is recharged for future use. This entire "loop" is considered a discharge cycle.
At installation time, the battery is at 100 percent of rated capacity. Each discharge and subsequent recharge reduces the relative capacity of the battery by a small percentage. The length of the discharge cycle will determine the reduction in battery capacity.
The "loaf of bread" analogy is most often used to illustrate the relationship between cycling and battery life. A loaf of bread can either be cut into many thin slices or a few thicker slices. Similarly, a lead battery can provide power over a large number of short cycles, or fewer cycles of longer duration.
Maintenance and Service The final factor to consider is the maintenance and service of the batteries and the back-up equipment. The gradual decrease in battery life can be monitored and evaluated through voltage checks, load testing and retorquing connections, as part of a periodic maintenance program. Without regular maintenance and service checks, your back-up battery may experience: Heat-generating resistance at the terminals Improper loading Reduced protection Premature failure With proper maintenance and service, the end of battery life can be estimated and replacements scheduled without any interruption or loss of backup power.
To charge a SLA battery, a DC voltage higher that the open circuit of 2.15 volts per cell is applied to the terminals of the battery. Any of the conventional charging techniques may be used, but to obtain maximum service life and capacity, along with acceptable recharge time, constant voltage-current limited charging is recommended.
During constant voltage or taper charging, the battery's current acceptance decrease as voltage and state of charge increase. The battery is fully charged once the current stabilizes at a low level for a few hours.
Cycle Applications: Limit initial current to 0.20C (C is the nominal A.H. capacity of the battery). Charge until battery voltage (under charge) reaches 2.45 per cell at 68 degrees F (20 deg.C). Hold at 2.45 volts per cell until current drops to approximately 0.01C ampere. Battery is fully charged under these conditions, and charge to "float" voltage.
"Float" of Stand-By Service: Hold battery across constant voltage source of 2.25 to 2.30 volts per cell continuously. When held at this voltage, the battery will seek its own current level and maintain itself in a fully charged condition.
Continuous over or undercharging is the single worst enemy of a lead acid battery. Caution should be exercised to insure that the charger is disconnected after cycle charging, or that the float voltage is set correctly. Because there is a chance of off-gassing hydrogen and oxygen if the battery is overcharged, it is important to provide adequate air circulation. ( Never charge or discharge a battery in a sealed enclosure.) Batteries should not be stored in a discharged state (or in a hot place). If a battery has been discharged for some time it may not readily take a charge. To overcome this, leave the charger connected and the battery for an extended time. The battery may eventually begin to accept charge. Due to the self-discharge characteristics of this type of battery, it is imperative that they be charged after 3-6 months of storage, otherwise permanent loss of capacity might occur as a result of sulfation. To prolong shelf life without charging, store batteries at 50 degrees F (10 deg. C) or less.
What is "end of useful life"? The IEEE defines "end of useful life" for a UPS battery as being the point when it can no longer supply 80 percent of its rated capacity in ampere-hours (AH). Because the relationship between amp-hours and load protection time is not linear, a 20% reduction in capacity results in a much greater reduction in protection time. For example, a UPS battery that supports a full load for 15 minutes when new, will support the same load for only about 8 minutes when it reaches its defined "end of life". When your battery reaches 80 percent of its rated capacity, the aging process accelerates and the battery should be replaced.
Which factors contribute most to end-of-life for UPS batteries? In North America, Western Europe and similar countries, positive grid corrosion has been the most common end-of-life factor for UPS batteries. This is a result of the normal aging process due to UPS battery chemistry (regardless of battery cycling) and involves the gradual breakdown of the inner wires of the positive grid within the battery.
In other areas, cycling is often the major contributing factor, due to very unpredictable utility power.
How do I make sure that my UPS batteries are maintained and serviced properly? With proper maintenance, battery life can be predicted and replacements scheduled without interrupting your operations. These are IEEE and OEM recommendations for general maintenance:
Comprehensive maintenance programs with a monthly inspection, and more rigorous quarterly and annual checks. Re-torquing all connections, as required Load testing Cleaning the battery area, as required What about my smaller UPS? Does this information to small units? Yes, this information applies to all UPS batteries. It is also important to understand that battery warranty does not necessarily equal battery life and the estimated range for battery life is five to eight years.
Are Maintenance Free batteries maintenance free? Though sealed batteries are sometimes called "maintenance free," they still require scheduled maintenance and service. The term "maintenance free" refers to the fact that they do not require fluid. Preventive maintenance is the key to maximizing your UPS battery service life.
What about the disposal of batteries? It is imperative that your service technicians adhere to EPA guidelines for the disposal of all UPS batteries. Remember, it is the owner's responsibility (and liability) to make sure these guidelines are followed.
Alkaline batteries, can be safely disposed of with normal household waste. An environmentally beneficial and economically feasible recycling process has not yet been developed for alkaline batteries, although Duracell is leading an international battery industry effort to develop such a technology. It is important to recognize that collecting, transporting and disposing of household batteries in a concentrated mass can create safety concerns. Discarded batteries are often not completely "dead." Concentrating used batteries in a container can bring these "live" batteries into electrical contact with one another, creating a safety risk. Any collection program must be organized to minimize such risk.
Disposing of small quantities of used household batteries (such as alkaline and zinc carbon batteries) with normal waste is preferable over disposing of concentrated quantities. You must consult with your local government Waste Management Authority regarding recycling and disposal regulations in your community.
NiCad (Nickel Cadmium)
NiCad batteries must be recycled. For details see: www.rbrc.org Rechargeable Battery Recycling Corporation, Phone: (800) 8 BATTERY.
Pb (Lead Acid) Batteries
Lead Acid batteries contain the same chemicals found in common automobile batteries. As a result, your local battery recycling facility should be able to recycle these products. Most of the time, they will provide you with the recycling service at no charge. In some cases, where large quantities of batteries are involved, local companies may be willing to pick up your used Lead Acid batteries. They may even pay you for them. We suggest you look in your local yellow pages for a Lead Acid battery recycling company in your area.
AGT Batterey Supply - Battery facts and battery care