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Battery Selection Guide



Choosing the appropriate battery for your application can be a difficult and time consuming process. With a variety of options to choose from, many people wonder where to start. When considering what type of battery to select, there are many factors which come into play. Some key considerations for appropriate battery selection include voltage, cycle life, service life, temperature requirements, reliability, safety, and replacement cost.

Battery Basics

Before you begin selecting the appropriate battery there are a few key terms to keep in mind.

Battery Cycle: a full charge followed by a full discharge.

Charge: The process of replenishing or replacing the electrical charge in a rechargeable cell or battery.

Cycle life: The amount of times a battery may be charged and discharged, Every time a battery is charged and discharged it uses one cycle.

Discharge Curve: The discharge curve is plotted as voltage against time, at a given current drain and temperature. A flat curve indicates that the battery discharge rate is steady until it is nearly discharged. A sloping curve indicates that the discharge rate changes over time.

Electrode: Part of the battery where the electrochemical reaction occurs.

Energy Density: The amount of energy a cell can contain.

Memory: Reversible capacity loss in NiCad and NiMH batteries. Memory can also be described as reversible capacity loss on nickel based batteries.

Overcharge: Charging a battery after it reaches full charge. Once an overcharge occurs, the battery can no longer absorb charge and therefore the battery heats up.

Polarity: the charges residing at the terminals of a battery

Primary Battery: a non-rechargeable battery.

Secondary Battery: A battery that is capable of being recharged.

Self Discharge: Capacity loss during storage due to the internal leakage between the positive and negative cell plates.

Terminals: The part of a battery to which the external electric circuit is connected

Voltage: The electric potential or potential difference of a battery. The voltage of a battery is the voltage of each cell times the number of cells in the battery.

Battery Types and typical applications

Alkaline batteries are the most common and least expensive battery type. They are considered a multi-use battery with good low and high temperature performance. Alkaline batteries are formulated to give peak performance and long life in both your high tech electronic devices and in your high-use standard household devices. The average alkaline battery will contain 1.5 volts per cell. Some common uses for alkaline batteries include MP3 players, cameras, pagers, toys, lights and radios.

Lithium Batteries are batteries with low self discharge rates. They are currently the fastest growing battery in terms of popularity because of their small size and their high power. These batteries have an excellent cycle life and discharge at a flat rate. Lithium batteries also have excellent low temperature performance and are commonly offered in 1.5 or 3 volt varieties. Most lithium batteries are non-rechargeable. Some common uses for lithium batteries include: personal organizers, smoke alarms, cameras, lights and security transmitters.

Nickel-Metal Hydride batteries, also referred to as NiMH, are rechargeable batteries with fast charging capabilities. Although these batteries offer very high performance rates, they do also have a higher self discharge rate; warmer temperatures will also accelerate the discharge rate. These batteries come in a variety of different voltages and can be operated at nominal temperatures. NiMH batteries are appropriate for devices requiring consistent high power output and a relatively long service life as they can withstand a couple hundred charges before replacement is required. Some common uses for NiMH batteries include: portable computers, cellular phones, camcorders, two way radios and handheld Televisions.

Nickel Cadimum batteries, also referred to as NiCad, are rechargeable batteries which provide considerable power. It is best to fully discharge the NiCad batteries before recharging. Older NiCad batteries which are not fully discharged before recharging can suffer from memory loss, meaning they lose the capability of becoming fully charged. NiCad batteries are used when extreme temperatures and a long service life is important. These batteries can be recharged about one thousand times before replacing. Some common uses for NiCad batteries include power tools, medical equipment, powered air purifying respirators, air monitors and laptop computers.

Primary vs. Secondary Batteries

Only Batteries that are labeled secondary or rechargeable are capable of being safely recharged. Attempting to recharge a primary or non rechargeable battery greatly increases the potential for leakage. Charges must be conducted in charging units specifically approved for each product type. The approved charger will vary depending on brand and model of both battery and charger. Rechargeable alkaline batteries have lower voltage rates than non rechargeable. Rechargeable batteries can be an economical alternative to primary batteries and are most appropriate for devices requiring consistent high power output.

While re-chargeable batteries are an inexpensive alternative to primary batteries, they do have a limited cycle life. Re-chargeable batteries work best when recharged before the battery goes dead. There are a couple advantages to re-chargeable batteries: they are environmentally friendly, and have a low self discharge.

Commonly Asked Questions

Q. What is the difference between nickel cadmium (NiCad) and nickel metal hydride (NiMH) batteries?
A. While both types of batteries are rechargeable, the NiMH batteries have higher energy density. NiMH batteries are considered more environmentally friendly and have relatively low toxicity and can be recycled. The NiCad batteries are considered toxic and harmful to the environment.

Q. Should I store my batteries in a refrigerator or freezer?
A. Storage of batteries in a refrigerator or freezer in not required or recommend for batteries manufactured today. Cold temperature storage may harm the batteries. In order to maximize the shelf life of batteries, they should be stored at room temperature.

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