TYPES OF BATTERIES

• PRIMARY  BATTERIES

Primary batteries are one shot deals, once they are drained, it is all over. Common primary batteries include carbon zinc batteries, alkaline batteries, mercury batteries, silver oxide batteries, zinc air batteries, and silver zinc batteries. Here are some common battery packages and their characteristics :

1. CARBON ZINC BATTERIES

        George Leclanche invented the carbon zinc battery in 1866. By 1868 it was adopted by the Belgium telegraph service and ultimately went on to be the standard for portable batteries around the world. The original leclanche cell was a wet cell, with the electrodes immersed in liquid electrolyte. Later developments moved the electrolyte to a wet paste, giving us the carbon zinc dry cell. A heavy duty version uses a zinc carbon zinc chloride chemistry, for a higher capacity.

        Carbon zinc batteries are general purpose, non rechargeable batteries made from cells that have open circuit voltages of 1.6 V. They are used for low to moderate current drains. The voltage discharge curve over time for a carbon zinc battery is nonlinear, whereas the current output efficiency decreases at high current drains. Carbon zinc batteries have poor low temperature performance but good shelf lives. This battery is susceptible to leaking its corrosive electrolyte. Carbon zinc batteries are used to power such devices as power toys, consumer electronic products, flashlights, cameras, watches, and remote control transmitters.

2. ZINC CHLORIDE BATTERIES

        A zinc chloride battery is a heavy duty variation of a zinc carbon battery. It is used in applications that require moderate to heavy current drains. Zinc chloride batteries have better voltage discharge per time characteristics and better low temperature performance than carbon zinc batteries. Zinc chloride batteries are used in radios, flashlights, lanterns, fluorescent lanterns, motor driven devices, portable audio equipments, communications equipments, electronic games, calculators, and remote control transmitters.

3. ALKALINE BATTERIES

        Alkaline batteries, as a class, were developed between 1895 and 1905 and were finally commercialized in the mid 1950s. This coincided with the rising popularity of electronic flash units in small portable cameras, which required the high power output the alkaline chemistry provided.

        Alkaline batteries are general purpose batteries that are highly efficient under moderate continuous drain and are used in heavy current or continuous drain applications. Their open circuit voltage is about 0.1 V less that that of carbon zinc cells, but compared with carbon zinc cells, they have longer shelf lives, higher power capacities, better cold temperature performance, more leak resistant and weigh about 50 percent less. One drawback of the rechargeable alkaline is its capacity fade. After each discharge, the battery will lose some of its capacity. After about 25 cycles, it is at 50% capacity, 50 cycles sees it at 20% capacity, where it appears to stay until the 100 cycle point at the end of its rated life. Alkaline batteries are interchangeable with carbon zinc  and zinc chloride batteries. Alkaline batteries are used to power such things like video cameras, motorized toys, photoflashes, electric shavers, motor driven devices, portable audio equipments, communications equipments, smoke detectors, and calculators. As it turns out, alkaline batteries come in both non rechargeable  and rechargeable forms.

4. MERCURY BATTERIES

        Mercury batteries are very small, non rechargeable batteries that have open circuit voltages of around 1.4 V per cell. Unlike carbon zinc and alkaline batteries, mercury batteries maintain their voltage up to a point just before the die. They have greater capacities, better shelf lives, and better low temperature performance than carbon zinc, zinc chloride, and alkaline batteries. Mercury batteries are designed to be used in small devices such as hearing aids, calculators, pagers, and watches.

5. LITHIUM BATTERIES

        Lithium batteries are non rechargeable batteries that use a lithium anode, one of a number of cathodes, and an organic electrolyte. Lithium batteries come with open circuit voltages of 1.5 or 3.0 V per cell. They have high energy densities, outstanding shelf lives (8 to 10 years), and can operate in a wide range of temperatures, but they have limited high current drain capabilities. Lithium batteries are used in such device like cameras, meters, cardiac pacemakers, CMOS memory storage devices, and liquid crystal displays (LCDs) for watches and calculators.

6. SILVER OXIDE BATTERIES

        Silver oxide batteries come with open circuit voltages of 1.85 V per cell. They are used in applications that require high current pulsing. Silver oxide batteries have flat voltage discharge characteristics up until death but also have poor shelf lives and are expensive. These batteries are used in such devices like alarms, backup lighting, and analog devices. As it turns out, like alkaline batteries, they too come in non rechargeable and rechargeable forms.

7. ZINC AIR BATTERIES

        Zinc air batteries are small, non rechargeable batteries with open circuit voltages of 1.15 to 1.4 V per cell. They use surrounding air (O₂) as the cathode ingredient and contain air vents that are taped over during storage. Zinc air batteries are long lasting, high performance batteries with excellent shelf lives and have reasonable temperature performance (about 0 to 50 ^o C, or 32 to 122 ^o F). These batteries typically are used in small devices such as hearing aids and pagers.

• SECONDARY BATTERIES

        Secondary batteries, unlike primary batteries, are rechargeable by nature. The actual discharge characteristics for secondary batteries are similar to those of primary batteries, but in terms of design, secondary batteries are made for long term, high power level discharges, whereas primary batteries are designed for short discharges at low power levels. Most secondary batteries come in packages similar to those of primary batteries, with the exception of, say, lead acid batteries and special purpose batteries. Secondary batteries are used to power such devices like laptop computers, portable power tools, electric vehicles, emergency lighting systems, and engine starting systems. Here are some common packages for secondary batteries and their characteristics :

1. LEAD ACID BATTERIES

        Secondary batteries became practical in 1860 with the invention of the lead acid battery by Raymon Gaston Plante. In 1881, Faure (and others) improved the yield of the lead acid cell by substituting a lead oxide paste for the pure lead of the plante cell.

        The largest problem associated with this battery is the damage caused by leaking acid. German researchers addressed this problem in the early 1960s by developing a gelled electrolyte. Working from another direction, other researchers developed a way to completely sealed the battery, preventing leaks. Either way, the sealed lead acid battery needs a little or no maintenance, which, while costing more, can be an advantage in some situations.

        A completely sealed battery, whether it is a gel cell or not, also prevents hydrogen gas from escaping when you recharge the battery, which is an improvement in safety when the battery is to be used indoors, such as on a robot or wheelchair. A gelled battery won't  leak even if it is punctured, but it can also have a slightly lower energy density than its liquid counterpart, at about 80% or so.

        Deep cycle batteries are a special variety of lead acid battery that can be discharged to low voltage levels without coming on to harm. Deep cycle batteries are typically used in marine or wheelchair applications. Regular car batteries are designed for short bursts of high ampere use to start the vehicle, with no deep discharges allowed. The electrode plates in a deep cycle battery are made thicker and less porous than the car battery, and will last two to four times longer than the car battery in deep cycle applications. Dual marine  batteries are a compromise of the two types.

        Lead acid batteries are rechargeable batteries with open circuit voltages of 2.15 V per cell while maintaining a voltage range under a load from 1.75 to 1.9 V per cell. The cycling life (number of times the battery can recharged) for lead acid batteries is around 1000 cycles. They come in rapid, quick, standard, and trickle charging rate types. Lead acid batteries have a charge retention time (time until the battery reaches 80 percent of maximum) of about 18 months. They contain a liquid electrolyte that requires servicing (replacement). Six lead acid cells make up a car battery.

2. NICKEL CADMIUM (NiCd) BATTERIES

        The technology behind the nickel cadmium battery was invented in 1899 by Waldmar Jungner, but the battery didn't reach commercial use until the 1930s when new electrodes were developed. The original version of the NiCd battery used a vented, unsealed cell that required regular maintenance. In the 1940s they perfected the sealed NiCd cell, though the cell do retain a need to breathe a bit, which is maintenance free, and the battery came to the fore in the 1950s. In 2000, it accounted for more than 50% of the world's rechargeable batteries for portable applications. Today's NiCd batteries can take a lot of abuse, both mechanical and electrical, and are cheaper than other batteries in cost per hour of use.

        The capacity of a Nicd isn't seriously affected by the discharge rate. If you extract current from the cell at a lower than specified rate, you get a little more life. Extracting current from the cell at a rate ten times the specified rate only lowers the capacity to about 70% of its rated level, so a 1000Ah battery would only give 700Ah.

        This battery has a surprisingly high capacity for current delivery. The AA battery shown has a recommended maximum continuous current draw of 9 amps, with 18 amp pulses allowed. There are two issues you face when you use a NiCd battery. One is the dreaded memory effect (which doesn't seem to plague other batteries), and the other is cell reversal. Though hotly disputed in hobbyist circles, the memory effect is very real in some, but not all, NiCd batteries. This effect appears because the battery retains the characteristics of previous discharges that is, after repeated shallow discharges, the battery may be unable to discharge beyond the earlier points. It would seem that, under certain conditions, electrodes in the cell can develop a crystalline growth. This growth reduces the area of the electrode exposed to the electrolyte. This leads to a voltage reduction and a loss of performance. Avoiding the memory effect is fairy simple. Fist, quick charge rather than trickle charge your NiCd batteries. Quick charging helps negate the effect of NiCd memory. Second, be sure to fully discharge your batteries to their 1 volt level, under a light load, on a regular basis.

        Cell reversal is a condition that can occur with multiple NiCd cells connected in series, such as in a multiple cell battery or a battery pack. Since not all cells are exactly the same, one cell in a chain may use up all of its charge before the others. As the pack continues to be used, a reverse charge is sent through the empty cell due to its charged neighbors. This reacts the water with the cathode, bonding the oxygen to the electrode and releasing hydrogen, which is then vented. This loss of water reduces the life of the cell. To prevent cell reversal, don't perform a deep discharge on a battery pack. It is save to cycle an individual cell to zero volts. In fact, timing the discharge cycle of a cell is one way of determining its exact capacity. With this information, a cell can be matched with other equivalent cell into a battery pack that is less prone to reversal.

        Nickel cadmium batteries contain rechargeable cells that have open circuit voltages of about 1.2 V. They are often interchangeable with carbon zinc and alkaline batteries. For the first 2/3 of its life, a nickel cadmium battery's discharge curve is relatively flat, but after that, its curve begins to drop. Nickel cadmium batteries weigh about a third as much as carbon zinc batteries. Placing these batteries in parallel is not rec