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Battery Guide

This guide can help you understand rechargeable batteries and proper handling that will maximize battery life.

The information contained in this document is for general purposes. It only represents technical opinions at the time of publishing. It does not guarantee any item or effect any product warranties given.

Frequently Asked Questions:

Why are rechargeable AA batteries 1.2V instead of 1.5V like alkaline batteries?

  • The chemistry of the battery. Everything chemical has a certain electric potential. The battery voltage is the difference between these two potentials. The classical chemicals for batteries was carbon and zinc, which produce 1.5V. Rechargeables, which are based on nickel and cadmium or nickel and hydrogen, produce 1.2V. The lead acid cells in your car battery, on the other hand, produce 2V, and lithium chemistries produce 3V while most Lithium Ion chemistries produce 3.6V.

Can I use 1.2V rechargeable AA, AAA, C, or D NiMh or NiCd cells in my device made for 1.5V alkaline batteries?

  • Yes. Generally speaking yes you may freely substitute one for the other. In many cases a NiMh rechargeable battery can significantly outperform an alkaline battery. For more on this topic please refer to this excellent paper on the subject.

Some Li-Ion or LiPo batteries have different voltage ratings, what's the difference between them?

  • All batteries have a nominal voltage rating: the typical voltage of a battery as it is discharged. Lithium-Ion and LiPo cells typically have a nominal voltage rating of 3.6V or 3.7V, and a few have 3.85V ratings. All else being equal, the higher voltage cells will store slightly more energy. In practice, differences in capacity rating and discharge curves can have much larger effects than the slight voltage difference. Since some of the best cells on the market are 3.6V, it is better to consider both voltages and narrow your search via other qualities first. The voltage difference gets larger when building battery packs with multiple cells in series, so you will often see packs labeled 7.2V or 7.4V, 10.8V or 11.1V, 14.4 or 14.8V, and so on. The difference is still slight regardless of whether it's a single cell or a large pack.

New Batteries:

Initial State

  • New rechargeable batteries come in a discharged condition and must be charged before use (refer to the manual for specific charging instructions).

Conditioning your batteries

  • Upon initial use (or after a prolonged storage period) batteries may require three to four charge/discharge cycles (often called conditioning/reconditioning) before achieving maximum capacity.

How often should I condition my batteries?

  • It is important to condition (fully discharge and then fully charge) the battery every two to three weeks. Failure to do so can significantly shorten the battery's life.

How do I condition my batteries?

  • Completely discharge the batteries (simply running your flashlight until the batteries are completely discharged will usually suffice). Then recharge the battery as instructed in the user's manual.

Battery Handling:

Prolonged Storage of Batteries

  • If the battery will not be in use for a month or longer, it is recommended that it be removed from the charger and stored in a cool, dry, clean place.

Self Discharge

  • A charged battery will eventually lose its charge if unused. It may therefore be necessary to recharge the battery after a storage period.

Battery Run Time

  • Actual battery run-time depends upon the power demands made by the equipment it powers. The total run-time of the battery is also heavily dependent upon the design of the equipment.

Batteries are warm to the touch

  • It is normal for a battery to become warm to the touch during charging and discharging.

Here are some basic tips for battery handling:

  • Do not short-circuit. A short-circuit may cause severe damage to the battery or even explosion.
  • Avoid dropping or impacting rechargeable batteries. This could result in the exposure of the corrosive cell contents.
  • Avoid exposing the battery to moisture or rain. Most flashlights are sealed against such exposure.
  • Always keep batteries away from fire or other sources of extreme heat. Never incinerate. Exposure of battery to extreme heat may result in an explosion.

Battery Technologies

  • Rechargeable batteries in portable lighting devices and two-way radios are principally made using Nickel Cadmium (NiCad), Nickel Metal Hydride (NiMH) or Lithium Ion. (Li-Ion) technologies. Rechargeable flashlight batteries found in lights made in the past several years are generally Lithium Ion.

Each type of rechargeable battery type has unique properties:

NiCad and NiMH

  • The main difference between the two is the fact that NiMH batteries (the newer of the two technologies) offer higher energy densities than NiCads. NiMH delivers approximately twice the capacity of its NiCad counterpart. What this translates into is increased run-time from the battery with no additional bulk to weigh down the device. NiMH also offers another major advantage: NiCad batteries tend to suffer from what is called the "memory effect". NiMH batteries are less prone to develop this affliction and thus require less maintenance and care. NiMH batteries are also more environmentally friendly than their NiCad counterparts since they do not contain heavy metals.


  • Li-Ion has quickly become the emerging standard for portable power. Li-Ion batteries produce the same energy as NiMH batteries but weigh approximately 35% less. This is crucial in applications such as portable two-way radios or notebook computers where the battery makes up a significant portion of the device's weight. Another reason Li-Ion batteries have become so popular is that they do not suffer from the memory effect. They are also environmentally friendly because they don't contain toxic materials such as Cadmium or Mercury.

Memory Effect

  • NiCad batteries, and to a lesser extent NiMH batteries, are prone to what is referred to as the "memory effect". What this means is that if a battery is repeatedly only partially discharged before recharging, the battery "forgets" that it has the capacity to further discharge all the way down. To illustrate: If you, on a regular basis, fully charge your battery and then use only 50% of its capacity before the next recharge, eventually the battery will become unaware of its extra 50% capacity which has remained unused. The battery will remain functional, but only at 50% of its original capacity.
  • The way to avoid the "memory effect" is to fully cycle (fully discharge and then fully charge) the battery at least once every two to three weeks. Simply leaving the device in the ON position and letting it run can discharge batteries completely. This will help insure your battery remains healthy. Once discharged, recharge the battery completely according to the manufacturer's instructions.

Battery Upgrade

  • NiCad, NiMH and Li-Ion are all fundamentally different from one another and should not be substituted unless the device has been pre-configured from the factory to accept more than one type of rechargeable battery technology. The difference between them stems from the fact that each type requires a different charging pattern to be properly recharged.
  • Therefore, the device's internal charger must be properly configured to handle a given type of rechargeable battery. Refer to the owners manual to find out which rechargeable battery types the particular device supports.

Maximizing Battery Performance

  • There are several steps you can take to insure that you get maximum performance from the rechargeable battery:

Break In New Batteries

  • New batteries come in a discharged condition and must be fully charged before use. It is recommended that you fully charge and discharge the new battery two to four times to allow it to reach its maximum rated capacity.

Prevent the Memory Effect

  • Keep the battery healthy by fully charging and then fully discharging it periodically. Exceptions to the rule are Li-Ion batteries, which do not suffer from the memory effect.

Keep the Batteries Clean

  • It's a good idea to clean dirty battery contacts with a cotton swab and alcohol. This helps maintain a good connection between the battery and the device.

Exercise the Battery

  • Do not leave the battery dormant for long periods of time. We recommend using the battery at least once every two to three weeks. If a battery has not been used for a long period of time, perform the new battery break in procedure described above.

Battery Storage

  • If you don't plan on using the battery for a month or more, we recommend storing it in a clean, dry, cool place away from heat and metal objects. NiCad, NiMH and Li-Ion batteries will self-discharge during storage; remember to break them in before use.

Battery Ratings

  • There are two ratings on every battery: volts and amp-hours (AH). The AH rating may also be given as milliamp-hours (mAH), which are one-thousandth of an amp-hour (for example, 1AH is 1000mAH). The voltage of the new battery should always match the voltage of your original.

Battery Lifetime

  • The life of a rechargeable battery operating under normal conditions is generally between 500 to 800 charge-discharge cycles. This translates into about three years of battery life for the average user. As the rechargeable battery begins to die, the user will notice a decline in the running time of the battery. When a battery that originally operated the flashlight for a whole shift is only supplying the user with an hour's worth of use, it's time for a new one.

Rechargeable vs. Non-Rechargeable

  • NiCad batteries are rechargeable, whereas Lithium and alkaline batteries are not rechargeable. Therefore, Lithium and alkaline batteries must be replaced by equivalent batteries of the same type. Attempting to replace these non-rechargeable batteries with a NiCad will result in a nonfunctional battery because the device lacks the proper charging circuitry to charge the NiCad battery.

Battery Terms Glossary:


One ampere-hour is equal to a current of one ampere flowing for one hour. A unit-quantity of electricity used as a measure of the amount of electrical charge that may be obtained from a storage battery before it requires recharging.

Ampere-Hour Capacity

The number of ampere-hours which can be delivered by a storage battery on a single discharge. The ampere-hour capacity of a battery on discharge is determined by a number of factors, of which the following are the most important: final limiting voltage; quantity of electrolyte; discharge rate; density of electrolyte; design of separators; temperature, age, and life history of the battery; and number, design, and dimensions of electrodes.


In a primary or secondary cell, the metal electrode that gives up electrons to the load circuit and dissolves into the electrolyte.

Aqueous Batteries

Batteries with water-based electrolytes.

Available Capacity

The total battery capacity, usually expressed in ampere-hours or milliampere-hours that are available to perform work. This depends on factors such as the endpoint voltage, quantity and density of electrolyte, temperature, discharge rate, age, and the life history of the battery.


A device that transforms chemical energy into electric energy. The term is usually applied to a group of two or more electric cells connected together electrically. In common usage, the term "battery" is also applied to a single cell, such as a household battery.

Battery Types

There are, in general, two type of batteries: primary batteries, and secondary storage or accumulator batteries. Primary types, although sometimes consisting of the same active materials as secondary types, are constructed so that only one continuous or intermittent discharge can be obtained. Secondary types are constructed so that they may be recharged, following a partial or complete discharge, by the flow of direct current through them in a direction opposite to the current flow on discharge. By recharging after discharge, a higher state of oxidation is created at the positive plate or electrode and a lower state at the negative plate, returning the plates to approximately their original charged condition.

Battery Capacity

The electric output of a cell or battery on a service test delivered before the cell reaches a specified final electrical condition and may be expressed in ampere-hours, watt-hours, or similar units. The capacity in watt-hours is equal to the capacity in ampere-hours multiplied by the battery voltage.

Battery Charger

A device capable of supplying electrical energy to a battery.

Battery-Charging Rate

The current expressed in amperes at which a storage battery is charged.

Battery Voltage, Final

The prescribed lower-limit voltage at which battery discharge is considered complete. The cutoff or final voltage is usually chosen so that the useful capacity of the battery is realized. The cutoff voltage varies with the type of battery, the rate of discharge, the temperature, and the kind of service in which the battery is used. The term "cutoff voltage" is applied more particularly to primary batteries, and "final voltage" to storage batteries. Synonym: Voltage, cutoff.


The rated capacity, in ampere-hours, for a specific, constant discharge current (where i is the number of hours the cell can deliver this current). For example, the C5 capacity is the ampere-hours that can be delivered by a cell at constant current in 5 hours. As a cell's capacity is not the same at all rates, C5 is usually less than C20 for the same cell.


The quantity of electricity delivered by a battery under specified conditions, usually expressed in ampere-hours.


In a primary or secondary cell, the electrode that, in effect, oxidizes the anode or absorbs the electrons.


An electrochemical device, composed of positive and negative plates, separator, and electrolyte, which is capable of storing electrical energy. When encased in a container and fitted with terminals, it is the basic "building block" of a battery.


Applied to a storage battery, the conversion of electric energy into chemical energy within the cell or battery. This restoration of the active materials is accomplished by maintaining a unidirectional current in the cell or battery in the opposite direction to that during discharge; a cell or battery which is said to be charged is understood to be fully charged.

Charge Rate

The current applied to a secondary cell to restore its capacity. This rate is commonly expressed as a multiple of the rated capacity of the cell. For example, the C/10 charge rate of a 500 Ah cell is expressed as, C/10 rate = 500 Ah / 10 h = 50 A.

Charge, State of

Condition of a cell in terms of the capacity remaining in the cell.


The process of supplying electrical energy for conversion to stored chemical energy.

Constant-Current Charge

A charging process in which the current of a storage battery is maintained at a constant value. For some types of lead-acid batteries this may involve two rates called the starting and finishing rates.

Constant-Voltage Charge

A charging process in which the voltage of a storage battery at the terminals of the battery is held at a constant value.


One sequence of charge and discharge. Deep cycling requires that all the energy to an end voltage established for each system be drained from the cell or battery on each discharge. In shallow cycling, the energy is partially drained on each discharge; i.e., the energy may be any value up to 50%.

Cycle Life

For secondary rechargeable cells or batteries, the total number of charge/discharge cycles the cell can sustain before it becomes inoperative. In practice, end of life is usually considered to be reached when the cell or battery delivers approximately 80% of rated ampere-hour capacity.

Depth of Discharge

The relative amount of energy withdrawn from a battery relative to how much could be withdrawn if the battery were discharged until exhausted.


The conversion of the chemical energy of the battery into electric energy.

Discharge, Deep

Withdrawal of all electrical energy to the end-point voltage before the cell or battery is recharged.

Discharge, High-Rate

Withdrawal of large currents for short intervals of time, usually at a rate that would completely discharge a cell or battery in less than one hour.

Discharge, Low-Rate

Withdrawal of small currents for long periods of time, usually longer than one hour.


Withdrawal of current from a cell.

Dry Cell

A primary cell in which the electrolyte is absorbed in a porous medium, or is otherwise restrained from flowing. Common practice limits the term "dry cell" to the Leclanché cell, which is the common commercial type.

Electrochemical Couple

The system of active materials within a cell that provides electrical energy storage through an electrochemical reaction.


An electrical conductor through which an electric current enters or leaves a conducting medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum. For electrolytic solutions, many solids, and molten masses, an electrode is an electrical conductor at the surface of which a change occurs from conduction by electrons to conduction by ions. For gases and vacuum, the electrodes merely serve to conduct electricity to and from the medium.


A chemical compound which, when fused or dissolved in certain solvents, usually water, will conduct an electric current. All electrolytes in the fused state or in solution give rise to ions which conduct the electric current.


The degree to which an element in a galvanic cell will function as the positive element of the cell. An element with a large electropositivity will oxidize faster than an element with a smaller electropositivity.

End-of-Discharge Voltage

The voltage of the battery at termination of a discharge.


Output capability; expressed as capacity times voltage, or watt-hours.

Energy Density

Ratio of cell energy to weight or volume (watt-hours per pound, or watt-hours per cubic inch).

Float Charging

Method of recharging in which a secondary cell is continuously connected to a constant-voltage supply that maintains the cell in fully charged condition.

Galvanic Cell

A combination of electrodes, separated by electrolyte, that is capable of producing electrical energy by electrochemical action.


The evolution of gas from one or both of the electrodes in a cell. Gassing commonly results from self-discharge or from the electrolysis of water in the electrolyte during charging.

Internal Resistance

The resistance to the flow of an electric current within the cell or battery.

Memory Effect

A phenomenon in which a cell, operated in successive cycles to the same, but less than full, depth of discharge, temporarily loses the remainder of its capacity at normal voltage levels (usually applies only to Ni-Cd cells).

Negative Terminal

The terminal of a battery from which electrons flow in the external circuit when the cell discharges.

Nonaqueous Batteries

Cells that do not contain water, such as those with molten salts or organic electrolytes.

Ohm's Law

The formula that describes the amount of current flowing through a circuit. Voltage = Current × Resistance.

Open Circuit

Condition of a battery which is neither on charge nor on discharge (i.e., disconnected from a circuit).

Open-Circuit Voltage

The difference in potential between the terminals of a cell when the circuit is open (i.e., a no-load condition).


A chemical reaction that results in the release of electrons by an electrode's active material.

Parallel Connection

The arrangement of cells in a battery made by connecting all positive terminals together and all negative terminals together, the voltage of the group being only that of one cell and the current drain through the battery being divided among the several cells. See Series Connection.


Refers to the charges residing at the terminals of a battery.

Positive Terminal

The terminal of a battery toward which electrons flow through the external circuit when the cell discharges.

Primary Battery

A battery made up of primary cells. See Primary Cell.

Primary Cell

A cell designed to produce electric current through an electrochemical reaction that is not efficiently reversible. Hence the cell, when discharged, cannot be efficiently recharged by an electric current. Note: When the available energy drops to zero, the cell is usually discarded. Primary cells may be further classified by the types of electrolyte used.

Rated Capacity

The number of ampere-hours a cell can deliver under specific conditions (rate of discharge, end voltage, temperature); usually the manufacturer's rating.


Capable of being recharged; refers to secondary cells or batteries.


State in which the gases normally formed within the battery cell during its operation, are recombined to form water.


A chemical process that results in the acceptance of electrons by an electrode's active material.


The structural part of a galvanic cell that restricts the escape of solvent or electrolyte from the cell and limits the ingress of air into the cell (the air may dry out the electrolyte or interfere with the chemical reactions).

Secondary Battery

A battery made up of secondary cells. See Storage Battery; Storage Cell.

Self Discharge

Discharge that takes place while the battery is in an open-circuit condition.


The permeable membrane that allows the passage of ions, but prevents electrical contact between the anode and the cathode.

Series Connection

The arrangement of cells in a battery configured by connecting the positive terminal of each successive cell to the negative terminal of the next adjacent cell so that their voltages are cumulative. See Parallel Connection.

Shelf Life

For a dry cell, the period of time (measured from date of manufacture), at a storage temperature of 21°C (69°F), after which the cell retains a specified percentage (usually 90%) of its original energy content.

Short-Circuit Current

That current delivered when a cell is short-circuited (i.e., the positive and negative terminals are directly connected with a low-resistance conductor).

Starting-Lighting-Ignition (SLI) Battery

A battery designed to start internal combustion engines and to power the electrical systems in automobiles when the engine is not running. SLI batteries can be used in emergency lighting situations.

Stationary Battery

A secondary battery designed for use in a fixed location.

Storage Battery

An assembly of identical cells in which the electrochemical action is reversible so that the battery may be recharged by passing a current through the cells in the opposite direction to that of discharge. While many non-storage batteries have a reversible process, only those that are economically rechargeable are classified as storage batteries. Synonym: Accumulator; Secondary Battery. See Secondary Cell.

Storage Cell

An electrolytic cell for the generation of electric energy in which the cell after being discharged may be restored to a charged condition by an electric current flowing in a direction opposite the flow of current when the cell discharges. Synonym: Secondary Cell. See Storage Battery.

Taper Charge

A charge regime delivering moderately high-rate charging current when the battery is at a low state of charge and tapering the current to lower rates as the battery becomes more fully charged.


The parts of a battery to which the external electric circuit is connected.

Thermal Runaway

A condition whereby a cell on charge or discharge will destroy itself through internal heat generation caused by high overcharge or high rate of discharge or other abusive conditions.

Trickle Charging

A method of recharging in which a secondary cell is either continuously or intermittently connected to a constant-current supply that maintains the cell in fully charged condition.


A normally sealed mechanism that allows for the controlled escape of gases from within a cell.

Voltage, Cutoff

Voltage at the end of useful discharge. (See Voltage, End-Point.)

Voltage, End-Point

Cell voltage below which the connected equipment will not operate or below which operation is not recommended.

Voltage, Nominal

Voltage of a fully charged cell when delivering rated current.

Wet Cell

A cell, the electrolyte of which is in liquid form and free to flow and move.