QUICK LINKS

Battery FAQs
New Batteries
Battery Handling
Battery Technologies
Battery Terms Glossary

ABOUT THIS 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.

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:

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. This translates into an 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

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 ensure 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 runtime 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:

Ampere-Hour	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.
Anode	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.
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.
Ci	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.
Capacity	The quantity of electricity delivered by a battery under specified conditions, usually expressed in ampere-hours.
Cathode	In a primary or secondary cell, the electrode that, in effect, oxidizes the anode or absorbs the electrons.
Cell	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.
Charge	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.
Charging	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.
Cycle	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.
Discharge	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.
Drain	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.
Electrode	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.
Electrolyte	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.
Electropositivity	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.
Energy	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.
Gassing	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).
Oxidation	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.
Polarity	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.
Rechargeable	Capable of being recharged; refers to secondary cells or batteries.
Recombination	State in which the gases normally formed within the battery cell during its operation, are recombined to form water.
Reduction	A chemical process that results in the acceptance of electrons by an electrode's active material.
Seal	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.
Separator	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.
Terminals	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.
Vent	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.

Battery Junction's Guide To Battery Care and Upkeep

By: The Battery Junction Team

Published: March 28th, 2022, 5:00pm EST

Battery Handling Basics

Just like any other technology, batteries should be handled with care, both to keep your battery and yourself safe! Here is a list of four simple things to keep in mind when using your batteries.

General Steps

Batteries are designed to be durable so that you can use them for any and all of your needs. In the unlikely event that a battery gets damaged for any reason, it can experience leakages of their corrosive liquid materials which can cause acid burns to your clothes, skin, or your devices. Please refer to the manufacturer's site on how to handle damaged units.

Depending on a battery's chemistry, each unit will have different requirements to best ensure its overall health, especially when stored. Always be sure to consult the manufacturer's guidelines for your battery's optimal storage temperatures. Maintaining optimal temperature conditions for your battery will not only ensure a lessened chance for mishaps occurring, but also prolong its shelf-life.

Keeping your batteries dry, whether when in use or in storage, will keep both your batteries and your devices safe. Ensuring your batteries stay dry can prevent a wide variety of different issues, letting you use them safely for as long as possible!

When a battery is no longer useable, be sure to properly dispose of it based on the manufacturer's safety guidelines. Depending on the chemistry, some batteries can be recycled. Please refer to this link for more information.

In-Depth Information

Now that you know some of the basics, here are some more specific things you can do to keep your batteries safe, and some information to understand battery health better!

Self Discharge During Storage

If a battery goes unused for an extended period of time, it is entirely natural for it to slowly lose its previously held charge, as it isn't possible for a battery to forever hold its full charge. If you remove a rechargeable battery from storage to use, it's always a good idea to recharge it as a precaution before using it again. For primary batteries, their shelf-life is based on this rate of self-discharge. For more information, please contact the manufacturer of your battery.

Run-Time Performance in Different Devices

A battery's run-time when in use will be different from its internal capacity. Different devices impose different power consumption demands which can affect your battery's overall performance. For example, while your battery might give one flashlight a 4 hour run-time, it may only provide a different flashlight with a 2 hour run-time. This isn't a reflection of something faulty with your battery, but that the device that is using the battery has an overall high power drain due to its specifications.

Internal Battery Temperatures and Overheating

When in use, your battery will experience a rise in temperature. This is usually perfectly normal and to be expected since the electrochemical process a battery uses to generate power will produce a certain amount of heat. However, if your battery starts to overheat beyond its normal specifications, it could potentially damage itself, your device, or even harm you. Be sure to check its specifications with the manufacturer's guidelines so that you know its safe operating temperature thresholds.

Rechargeable In-Depth Information

When you first receive your rechargeable battery, there are a few important details you should know and certain maintenance steps to take before jumping right into using it.

A Rechargeable Battery's Lifespan

The lifespan of a rechargeable battery is measured in the number of full discharge to charge cycles it is capable of before reaching the end of its rated specifications. When this end is met, it is recommended that you replace the battery. Weaker batteries usually last a few hundred cycles, while stronger, more efficient batteries can last for thousands of cycles. Depending on how often you use a battery, it can last anywhere from a few months to multiple years before becoming inoperable. If your batteries are constructed with a NiMH or NiCd chemistry, make sure you consult the manufacturer's website and perform proper conditioning to ensure they last as long as possible.

How to Condition a NiMH or NiCd Battery

Recharge your NiMH or NiCd battery to full capacity. Next, place the battery in a device, such as a flashlight, and run it until the battery fully discharges. Repeat this process three to four times. Finally, recharge your now conditioned battery to maximum capacity. For best results, repeat this process every two to three weeks. Please note that this is only meant for NiMH or NiCd batteries, and that not performing regular conditioning can cause the Memory Effect in nickel-cadmium and nickel-metal hybrid batteries, which will greatly reduce your battery's health and lifespan.

What is the Memory Effect?

When your nickel-cadmium or nickel-metal hyrbid battery memorizes a shortened life cycle caused by repeated incomplete discharges, reducing its overall lifespan.

How to Recharge Your Batteries

There are a wide variety of different ways for you to charge your rechargeable batteries. Many batteries can be recharged through the device that they're installed in, while others use a dedicated external charging device that plugs into a wall outlet. Some batteries, however, come with a built-in charging port for you to recharge them directly with a USB charging cable. Please always make sure to recharge your batteries according to the manufacturer's guidelines. Do not, under any circumstances, recharge a battery with a charging method that it is not designed for as this can cause serious complications.

Warning

Make sure that you recharge your batteries in a dry environment that is room or cool temperature. Please also ensure that you recharge your batteries in a location where they cannot get damaged from falls or impacts. Also, do not leave your charging batteries unattended as they could potentially overcharge.

Caution: Rechargeable batteries should never be thrown away in the trash under any circumstances. These batteries should always be recycled by dropping them off at dedicated recycling locations. Refer to this link for more information.

Primary and Secondary Batteries

There are two types of batteries that all units fall under: Primary Batteries and Secondary Batteries.

Primary Batteries

Without a need to recharge, Primary Batteries are inherently more reliable as they need less upkeep. For this reason, Primary Batteries are a go to resource for many medical purposes, such as for hearing aids and pacemakers. Due to their higher level of reliability, they are incredibly effective for tactical missions as well. In these instances, personnel will carry a variety of spares to replace discharged batteries. They are also great in devices that have a low power drain such as a TV remote. Their low self-discharge rates ensure a long shelf life. However, they do need to be replaced and disposed of after being fully discharged.

Secondary Batteries

A battery built from secondary cells which can be recharged by reversing the flow of the electrical current. This process restores the battery's active materials through a reversed electrochemical reaction after a full discharge.

With the ability to recharge, Secondary Batteries are great for work tools, household appliances, and personal electronic devices. This allows you to power the same device for far longer. They are also well suited for devices that have higher power drains. The reusable nature of these rechargeable batteries makes them more environmentally friendly and recyclable. However, this is not a recommendation; due to their construction, they cannot be safely disposed of like Primary Batteries. Please consult the manufacturer's guidelines for proper recycling methods. Also, please refer to this link for recycling information and locations.

General Specs

	Primary	Secondary
Rechargeable	NoNever attempt to recharge	Yes
Environmental Impacts	HighDue to being disposable	LowDue to being reusable and recyclable
Disposal Method	Consult battery manufacturer	Recycle

Primary

	Typical Shelf Life	Typical Safe Temperature Range
Zinc	2years	0~45°, -10~25°celsius
Alkaline	5years	-18~55°, -40~50°celsius
Lithium-iron	10years	-40~60°, -40~60°celsius
Lithium 3V	10years	-30~75°, -55~75°celsius
Silver-oxide	5years	-10~55°, -10~55°celsius
Zinc-air	2years	-10~55°, 10~25°celsius

Secondary

	Typical Shelf Life	Typical Safe Temperature Range
NiCd	5years	-20~65°, 10~30°, 0~50°celsius
NiMH	5years	0~50°, -20~30°, 0~50°celsius
LSD NiMH	5years	0~50°, -20~30°, 0~50°celsius
Li-Ion (ICR)	10years	-20~60°, -20~50°, 0~45°celsius
Li-Ion (IMR)	3years	-20~60°, -20~50°, 0~45°celsius
Li-Ion (INR)	3years	-20~60°, -20~50°, 0~45°celsius
Li-Poly	3years	-20~60°, -20~25°, 0~45°celsius
Lead Acid	6months	-40~60°, -40~50°, -20~50°celsius

Additional Terms

Terms (A-B)

Ampere-Hour	A unit of electric charge used to measure a battery's capacity
Ampere‐Hour Capacity	A battery's maximum charge and how long it can last on a singular full charge
Anode	The metal electrode that gives up electrons to the load circuit and dissolves into the electrolyte, only in primary and secondary cells
Aqueous Batteries	Batteries which use a saline solution as an electrolyte for lithium ion transfers
Available Capacity	The maximum capacity of battery that can be used to power your devices, typically expressed in ampere-hours or milliampere-hours
Battery	A device which converts chemical energy into electrical energy through a process of oxidation and reduction
Battery Types	Batteries typically come in two different forms. Primary batteries are made to only allow one continuous or intermittent discharge, meaning it cannot be recharged. Secondary (also known as accumulator) batteries can be recharged through a reversed discharge flow
Battery Capacity	The total amount of electrical charge that a battery can hold (usually measured in ampere-hours, watt hours, or some other comparable unit)
Battery Charger	A device designed to supply a battery with more electrical energy after a discharge
Battery-Charging Rate	The rate at which a battery can be recharged after a discharge
Battery Voltage, Final	The voltage at which a battery is considered fully discharged

Terms (C-D)

Capacity	The total amount of electrical charge that a battery can hold, typically measured in ampere-hours
Cathode	The electrode that oxidizes the anode and absorbs electrons
Cell	The basic building block of a battery, an electrochemical device which can store electricity. It is made from positive and negatively charged plates, a separator, and an electrolyte.
Ci	A battery's capacity rating, the ampere-hours that can be delivered through a constant discharge current from the battery over a set period of time (i represents the number of hours, usually between 1-10 hours or 20 hours)
Charge	The process of converting electrical energy into chemical energy in a dead battery by restoring its active materials through a reversed discharge current, which is then stored for future use
Charging	Supplying a battery with electrical energy to restore the active materials of a battery, which converts the electricity into chemical energy
(State of) Charge	The current charge level in a battery's capacity
Charge Rate	The measurement of the current used to fully recharge a battery based on its capacity. This process is measured as multiples of a battery's rated capacity (Example: C/10 means the charge rate in 10 hours, so for a 500Ah capacity battery, this would mean that C/10 = 500Ah / 10h = 50A)
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
Cycle	One full sequence of a battery charging and discharging
Cycle Life	The total number of charge and discharge cycles that a rechargeable battery can perform before becoming fully inoperative. A battery is considered to have reached the end of its Cycle Life when it can no longer charge beyond 80% of its total capacity
Deep Discharge	The total withdrawal of a battery's electrical energy before battery has been fully recharged
Depth of Discharge	The amount of power that can actually be used from a battery's total capacity without shortening its lifespan (Example: A battery with a DoD of 80% can only use 80% of its total capacity without damaging itself)
Discharge	The conversion of a battery's chemical energy into electrical energy
Discharge (High-Rate)	Large electrical current withdrawals from a battery which drain it in a short period of time
Discharge (Low-Rate)	Small electrical current withdrawals from a battery which drain it over a long period of time
Drain	The withdrawal of an electrical current from a battery
Dry Cell	A primary battery which absorbs the electrolytes into a porous material to restrain the flow of energy

Terms (E-F)

Electrochemical Couple	The battery's system of active materials that store chemical enery and generate electrical energy through electrochemical processes
Electrode	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
Electrolyte	A chemical compound which conducts an electrical current by producing ions when combined with solvents (usually water)
Electropositivity	The degree to which an element within a galvanic cell can give electrons in order to oxidize
End‐of‐Discharge	The voltage of a battery when it is fully discharged
Energy	A battery's ability to power electrical devices (expressed as capacity times voltage, or watt-hours&rpar'
Energy Density	The ratio of a cell's energy to its weight or volume
Float Charging	A style of recharging in a secondary cell where it is connected to and continuously charged from a constant-voltage charger which will keep it in a fully charged state

Terms (G-I)

Galvanic Cell	A combination of electrodes which are separated by an electrolyte that can produce electrical energy through electrochemical reactions
Gassing	When electrodes of a cell begin to produce gas, which most commonly occurs due to self discharge or from electrolysis of water in the elctrolyte during charging
Internal Resistance	Resistance against the flow of electrical currents within the cell or battery

Terms (M-N)

Memory Effect	When a battery is constantly discharged before being fully charged, causing it to progressively lose some of its maximum capacity
Negative Terminal	The terminal of a battery through which releases electrons during the discharge cycle
Nonaqueous Batteries	Cells and batteries that do not use water

Terms (O-P)

Ohm's Law	The formula that describes the amount of current flowing through a circuit (Voltage= Current x Resistance)
Open Circuit	An electrical circuit which is not complete and is disconnected from any charge
Open-Circuit Voltage	The difference in potential between a battery's terminals of a cell when the circuit is open
Oxidation	A chemical reaction which releases electrons by the electrode's active material
Parallel Connection	When the cells in a battery are all connected by their positive terminals together and their negative terminals together, which generates the voltage of one cell, but disperses the drain amongst all of the cells
Polarity	The type of charge (positive or negative) of the battery's terminals at its ends
Positive Terminal	The terminal of a battery which receives electrons during the discharge cycle
Primary Battery	A battery constructed solely from primary cells, one that cannot be recharged (These batteries should be immediately discarded after being fully discharged)
Primary Cell	A cell which produces an electric current through an irreversible electrochemical reaction, a cell which cannot be recharged (These cells should be immediately discarded after being fully discharged)

Terms (R-S)

Rated Capacity	The amount of ampere-hours a cell delivers under specific conditions, usually determined by the manufacturer
Rechargeable	Capable of being charged after fully discharging
Recombination	When the gases in a battery recombine to form water during use
Reduction	The chemical process by which the active material of a battery's electrode accepts electrons
Seal	Part of a galvanic cell that restricts the solvent and electrolytes from escaping the cell while preventing air from entireing the cell
Secondary Battery	A battery built from secondary cells which can be recharged by reversing the flow of the electrical current
Secondary Cell	A cell which can be recharged by reversing the flow of the electrical current to restore the active chemical materials
Self Discharge	Discharge that occurs to a battery while in an open-circuit condition
Separator	The permeable membrane that allows ions to pass through the cell without causing short-circuiting
Series Connection	When cells are arranged to connect their positive terminals to the negative terminals of other batteries to create a cumulative voltage
Shelf Life	The period of time that a dry cell can maintain its original energy content (usually 90%) while in optimal storage temperature (21°C or 69°F) from the date it was manufactured
Short-Circuit	When an abnormal connection between a battery's cathode and anode causes the electric current to become limited by creating an unintended traveling path
Short-Circuit Current	The current that is delivered when a cell short-circuited
Starting-Lighting-Ignition (SLI) Battery	A battery designed to start internal combustion engines, usually used to power vehicles when the engine is shut off (In case of emergencies, this battery can be used to power other items)
Stationary Battery	A secondary battery meant to be used in a fixed location
Storage Battery	Economically rechargeable batteries, synonymous to Secondary Batteries
Storage Cell	Economically rechargeable cells, synonymous to Secondary Cells

Terms (T-W)

Taper Charge	A method of charging in which recharging starts with a high current, but as the battery's charge increases from a low charge level, the charging current will decrease
Terminals	The ends of the battery that the external electric circuit connects to
Thermal Runaway	When a lithium-ion battery destroys itself due to overheating caused by overcharging, excessive discharge, or other dangerous conditions (This condition can produce gas, an explosion, excess heat, smoke, and fire)
Trickle Charging	Charging a battery at the same rate as its self-discharge rate
Vent	A mechanism of some batteries that allows gas to escape the cell in a controlled manner to preserve its health
Voltage, Cutoff	A batteries voltage level at the end of a discharge
Voltage, End-Point	A cell's voltage level in which the connected equipment will no longer function and should no longer be used until the cell is recharged
Voltage, Nominal	The voltage of a fully charged cell while it delivers a rated current
Wet Cell	A cell that uses liquid for the electrolyte to flow freely through

To get the latest in flashlight news, be sure to subscribe to our email newsletter! You can also follow our socials on Facebook, Instagram, Youtube and Twitter to get sneak peeks at newly-released lights. Thank you for reading! – The Battery Junction Team

QUICK LINKS

ABOUT THIS GUIDE

Frequently Asked Questions:

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

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

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

New Batteries:

Initial State

Conditioning your batteries

How often should I condition my batteries?

How do I condition my batteries?

Battery Handling:

Prolonged Storage of Batteries

Self Discharge

Battery Run Time

Batteries are warm to the touch

Basic Tips for Battery Handling:

Battery Technologies

Each Type of Rechargeable Battery:

NiCad and NiMH

Li-Ion

Memory Effect

Battery Upgrade

Maximizing Battery Performance

Break-In New Batteries

Prevent the Memory Effect

Keep the Batteries Clean

Exercise the Battery

Battery Storage

Battery Ratings

Battery Lifetime

Rechargeable vs. Non-Rechargeable

Battery Terms Glossary:

Ampere-Hour

Ampere-Hour Capacity

Anode

Aqueous Batteries

Available Capacity

Battery

Battery Types

Battery Capacity

Battery Charger

Battery-Charging Rate

Battery Voltage, Final

Ci

Capacity

Cathode

Cell

Charge

Charge Rate

Charge, State of

Charging

Constant-Current Charge

Constant-Voltage Charge

Cycle

Cycle Life

Depth of Discharge

Discharge

Discharge, Deep

Discharge, High-Rate

Discharge, Low-Rate

Drain

Dry Cell

Electrochemical Couple

Electrode

Electrolyte

Electropositivity

End-of-Discharge Voltage

Energy

Energy Density

Float Charging

Galvanic Cell

Gassing

Internal Resistance

Memory Effect

Negative Terminal

Nonaqueous Batteries

Ohm's Law

Open Circuit

Open-Circuit Voltage