Starting Batteries and Deep-Cycle Batteries
When people think about lead-acid batteries, they usually think about a car battery. These are starting batteries. They deliver a short burst of high power to start the engine.
There also are deep-cycle batteries. You'd find these on boats or campers, where they're used to power accessories like trolling motors, winches or lights. They deliver a lower, steady level of power for a much longer time than a starting battery.
Lead-acid batteries are used for a vast number of purposes, but all batteries provide either starting or deep cycle power. The only difference is how much power is delivered and how long it needs to be delivered.
For more information on lead-acid batteries, select a link from the list below:
What a car battery does:
- A car battery supplies power to the starter and ignition system to start the engine.
- A car battery supplies the extra power necessary when the vehicle's electrical load exceeds the supply from the charging system.
- A car battery acts as a voltage stabilizer in the electrical system. The battery evens out voltage spikes and prevents them from damaging other components in the electrical system.
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The Role of the Standby Battery:
Standby batteries supply electrical power to critical systems in the event of a power outage. Hospitals, telecommunications systems, emergency lighting systems and many more rely on lead-acid standby batteries to keep us safe without skipping a beat when the lights go out.
Standby batteries are voltage stabilizers that smooth out fluctuations in electrical generation systems. These batteries temporarily hold large electrical loads as electric utilities switch from one generation system to another; as such they can be a lifesaving bridge.
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What the motive battery does:
- A motive battery powers the motor that drives an electric vehicle, such as forklift truck.
- A motive battery powers accessories like headlights on an electric vehicle.
- Motive batteries provide power for a specific purpose on an electric vehicle, such as the lift on an electric forklift truck.
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How a Battery is Made
Batteries are made of five basic components:
- A resilient plastic container.
- Positive and negative internal plates made of lead.
- Plate separators made of porous synthetic material.
- Electrolyte, a dilute solution of sulfuric acid and water, better known as battery acid.
- Lead terminals, the connection point between the battery and whatever it powers.
The manufacturing process begins with the production of a plastic container and cover. Most automotive battery containers and their covers are made of polypropylene. For a typical 12-volt car battery, the case is divided into six sections, or cells, shaped somewhat like one row in an ice-cube tray. The cover is dropped on and sealed when the battery is finished.
The process continues with the manufacture of grids from lead or an alloy of lead and other metals. A battery must have positive and negative plates to conduct a charge.
Next, a paste mixture of lead oxide -- which is powdered lead and other materials -- sulfuric acid and water is applied to the grids. Expander material made of powdered sulfates is added to the paste to produce negative plates.
Inside the battery, the pasted positive and negative plates must be separated to prevent short circuits. Separators are thin sheets of porous, insulating material used as spacers between the positive and negative plates. Fine pores in the separators allow electrical current to flow between the plates while preventing short circuits.
In the next step, positive plates are paired with negative plates and separators. This unit is called an element, and there is one element per battery cell, or compartment in the container. Elements are dropped into the cells in the battery case. The cells are connected with a metal that conducts electricity. The lead terminals, or posts, are then welded on.
The battery is then filled with electrolyte - or battery acid -- a mixture of sulfuric acid and water, and the cover is attached. The battery is checked for leaks.
The final step is formation. During this step, the battery terminals are connected to a source of electricity and the battery is charged for many hours. When the battery is fully formed, it moves to another line where the case is cleaned, if necessary, and the labels are attached.
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How a Battery Works
A battery stores electricity for future use. It develops voltage from the chemical reaction produced when two unlike materials, such as the positive and negative plates, are immersed in the electrolyte, a solution of sulfuric acid and water. In a typical lead-acid battery, the voltage is approximately 2 volts per cell, for a total of 12 volts. Electricity flows from the battery as soon as there is a circuit between the positive and negative terminals. This happens when any load that needs electricity, such as the radio, is connected to the battery.
Most people don't realize that a lead-acid battery operates in a constant process of charge and discharge. When a battery is connected to a load that needs electricity, such as the starter in your car, current flows from the battery. The battery begins to be discharged.
In the reverse process, a battery becomes charged when current flows back into it, restoring the chemical difference between the plates. This happens when you're driving without any accessories and the alternator puts current back into the battery.
As a battery discharges, the lead plates become more chemically alike, the acid becomes weaker, and the voltage drops. Eventually the battery is so discharged that it can no longer deliver electricity at a useful voltage.
You can recharge a discharged battery by feeding electrical current back into it. A full charge restores the chemical difference between the plates and leaves the battery ready to deliver its full power.
This unique process of discharge and charge in the lead-acid battery means that energy can be discharged and restored over and over again. This is what's known as the cycling ability in a battery.
If the battery won't start your car, you usually refer to it as "dead," even though that's not technically correct. A battery that's merely discharged - from leaving your headlights on or from a damaged alternator -- can be recharged to its full capacity. But a battery that's at the end of its service life can't be recharged enough to restore it to a useful power level. Then it truly is dead, and must be replaced.
If the battery is discharged and not dead, you can jump-start it from another fully charged battery. About 30 minutes of driving should allow the alternator to fully charge the battery. But if the alternator or another part of the electrical system in your car is damaged, the battery will not recharge and a mechanic or service station also will not be able to recharge it. So if your battery keeps discharging, have your electrical system checked before you replace it. What looks like a bad battery could be an electrical system problem. If you have a bad component in the electrical system, it will keep draining a new battery, and you'll be stranded again and again.
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Different Kinds of Batteries
Small consumer sealed lead-acid batteries are six-volt batteries that provide extended cycling service. They power consumer products and tools like drills, flashlights, electric starters for gas lawn mowers, and children's toy cars.
All sealed lead-acid batteries are made of recycled lead and plastic, and all are recycled at the end of their service lives. For more information on battery recycling, go to the recycling section.
These batteries start engines on cars, boats and other vehicles. They provide a short burst of strong power to get the engine started.
The deep cycle battery powers electrical accessories, such as lights, trolling motors or winches. They provide a low, but steady level of power for a longer period of time than a starting battery.
There are also batteries designed to serve a balanced combination of starting and deep cycle service. These batteries are referred to as dual purpose. The have high starting power for engine cranking but also built to withstand the cycle service demands from multiple accessory loads.
All lead-acid batteries are made of recycled lead and plastic, and all are recycled at the end of their service lives. For more information on battery recycling, go to the recycling section.
These batteries, used for industrial purposes, take a deep cycle battery further. They provide low, steady power over a much longer period of time than a typical deep cycle battery. The plates are much thicker, and there is usually much more total energy available for a longer period of time. An industrial battery lasts for years.
Batteries are also used in Stationary applications that provide critical back up power to systems that need a constant power supply. These batteries are usually not called upon to deliver power often, but when they do, they need to deliver a lot of power, quickly and for enough time so that reserve power generators can take over. Many times, these batteries are configured as systems to accommodate large power demands.
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When the French scientist, Gaston Plante, invented the lead-acid battery in 1859, he could not have envisioned the critical role his creation would play today in transportation, communication, electric utilities and as emergency backup systems. Without them, 21st century life would not be possible.
The development of more and more battery-powered devices and applications has fueled demand for new and different battery chemistries. Researchers have been looking for a chemistry that is at once powerful, long-lived, safe, inexpensive, lightweight and recyclable.
Following is a brief summary of lead-acid and alternate battery chemistries and their advantages and disadvantages.
Advantages: This chemistry has been proven over more than 140 years. Batteries of all shapes and sizes, available in sealed and maintenance-free products, are mass-produced today. In their price range, lead-acid batteries provide the best value for power and energy per kilowatt-hour, have the longest life cycle and a large environmental advantage in that they are recycled at an extraordinarily high rate. (Ninety-seven percent of the lead is recycled and reused in new batteries.). No other chemistry can touch the infrastructure that exists for collecting, transporting and recycling lead-acid batteries.
Disadvantages: Lead is heavier compared to some alternative elements used in other technologies; however, certain efficiencies in current conductors and other advances continue to improve on the power density of a lead-acid battery's design.
Advantages: This is a mechanically rechargeable primary battery system with a capacity equal to 15-20 cycles on a lead-acid system (a cycle refers to a discharge and a charge).
Disadvantages: Its components must be replaced frequently, water must be added and sludge must be removed. When combined with the expense of reprocessing aluminum, the system is nowhere near commercialization.
Advantages: It has a high specific energy (the number of hours of operation for a given weight) making it a huge success for mobile applications such as phones and notebook computers.
Disadvantages: More expensive than lead. The cost differential is not as apparent with small batteries for phones and computers, and owners of these devices may not realize that they are paying much more per stored kilowatt hour than other chemistries. However, because automotive batteries are larger, the cost becomes more significant. In addition, currently there is no established system for recycling large lithium-ion batteries.
Advantages: This chemistry is reliable, can operate in a range of temperatures, tolerates abuse well and performs well after long periods of storage.
Disadvantages: It is three to five times more expensive than lead-acid, its materials are toxic and the recycling infrastructure for larger nickel-cadmium batteries is very limited.
Advantages: It is reliable and lightweight. In hybrid vehicles, these batteries have equal to 100,000 miles.
Disadvantages: The metals in the battery are 25 times more expensive than lead. Nickel has been identified as a carcinogen. Hybrid vehicles have not been on the road long enough to allow the batteries to completely prove their projected cycle life. No significant recycling capability exists.
Note: The Advanced Lead-Acid Battery Consortium has helped to develop and test an advanced lead-acid battery powered system that operates at the partial state of charge demands necessary for a hybrid vehicle and recently equipped a Honda Insight with this system. Advanced lead-acid batteries will challenge the more expensive nickel metal hydride system in hybrid vehicles today.
Advantages: This chemistry has good energy density, good operating temperature range and performs reasonably well after long periods of storage.
Disadvantages: it is expensive and its life cycle, while improved during the past few years, is still merely adequate. So there has been no breakthrough in this chemistry.
Advantages: This chemistry is about as efficient as lead-acid, but has three to four times more specific energy (the number of hours of operation for a given weight).
Disadvantages: Twenty seven years of research has yielded only one commercial application – load leveling by electric utilities in Japan.
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