When determining which battery should be used for a particular application, we suggest that you consider the following four questions. You can click on each question for an overview and explanation of the factors involved.
Primary vs. Secondary
Primary batteries are used once, then discarded. They have the advantage of convenience and cost less per battery, with the down side of costing more over the long term. Generally, primary batteries have a higher capacity and initial voltage, and a sloping discharge curve. Primary batteries do not presently require special disposal.
Secondary batteries are the rechargeable batteries. They have the advantage of being more cost-efficient over the long term, although individual batteries are more expensive. Generally, secondary batteries have a lower capacity and initial voltage, a flat discharge curve, and varying recharge life ratings. Ni-Cd and small-size lead acid batteries require special disposal and should not be simply thrown away.
Recommended Temperature Usage
Not all batteries are recommended for all temperature extremes; choose a battery which matches your environment.
Recommended Devices
Because different batteries are recommended for different device types, you should choose a battery which matches your type.
High Discharge Rate Devices can be loosely defined as those with current consumption of 600 mA or higher.
Low to Moderate Discharge Rate Devices can be loosely defined as those with current consumption of less than 600 mA.
Storage
Batteries will self-discharge over time. If you will be using the battery intermittently, you would want a battery with a longer storage life. Storage is an indicator of how long the battery will last before self-discharge renders the battery dead. Generally, there will be a date code on the battery or packaging such as 1A2. This code indicates that the battery was packaged in January of 2002.
Batteries should not be stored in the device if the device is not being used. Leaving batteries in a battery compartment for long periods (a week or longer) can cause the batteries to leak. Two or three days should not be a problem; however, if the device will be unused for a week or longer, we recommend that the batteries be removed.
Other factors to consider when choosing a battery include initial voltage, capacity, the discharge curve, recharge life (for secondary batteries) and disposal requirements. The Technical Information section has a Battery Comparison Table which allows you to quickly compare these ratings.
Initial Voltage
This is the voltage when the battery is new and fully charged. Devices will often use the voltage as the indicator for battery life. When it drops below a given point, the battery is considered dead. A higher initial voltage generally indicates longer battery life.
For primary cylindrical batteries and rechargeable alkalines, the initial voltage is 1.5 volts. For the other secondary batteries, the initial voltage is between 1.2 and 1.25 volts.
Capacity
In rechargeable batteries, capacity is listed as ### mAh (or ## Ah); this information allows you to estimate battery life in a device with known current drain. In alkaline batteries, the sloping discharge curve makes it impossible to accurately provide a mAh rating; the rating would vary depending on discharge rate and temperature.
Discharge Curve: Flat or Sloping
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. Generally speaking, primary batteries have sloping discharge curves and secondary batteries have flat curves.
Recharge Life
This indicates the number of times that a rechargeable battery can be recharged. The number varies by battery type.
Disposal
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