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Battery Tips Battery Terms Battery FAQ

Battery FAQ

What is a battery?
How does a battery work?
What are the different categories of batteries?
What are the different battery chemistries?
What is Volt?
What is Amperage?
What is millampere -Hours (mAH)?
What is "Memory Effect"?
What is cycle life?
What is self-discharge?
What charging precautions should be taken when charging a battery pack?
What steps should be followed for the initial charge cycle to maximize battery performance?
What precautious should be taken when storing battery packs?
How should batteries be charged after they have been in storage (or un-used) for over three months?
How often should a battery be replaced?



Battery Types

Nickel Cadmium (Ni-CD)
Nickel Metal Hydride (Ni-MH)
Lithium-Ion (Li-Ion)

What is a battery?
A battery is a device that generates an electrical current by chemical reaction.

How does a battery work?
Batteries operate on a simple theory: two different metals in contact with an electrolyte will produce a flow of electrons (electricity) when all elements are in contact with each other.

What are the different categories of batteries?
Batteries fall into two general categories -- primary batteries and secondary batteries.

Primary batteries cannot be recharged or "brought back to life" once they have used up their power. Examples of primary batteries include alkaline batteries that are commonly used in flashlights, portable radios and miscellaneous consumer electronics devices.

Secondary batteries , also known as storage batteries, are capable of being recharged and reused up to 500 times (charge/dis charge cycles). Nickel Cadmium, Nickel-Metal Hydride and Li-Ion batteries (used in many portable electronic devices such as two-way radios and bar code scanners) are examples of this type (belong to this category).

What are the different battery chemistries?
The following are the three most common chemistries utilized in battery cells. Their general characteristics and primary uses are noted below:

Nickel Cadmium (Ni-CD)
Nickel Cadmium is one of the most rugged rechargeable batteries. They are very suitable for us e in small, portable devices such as two-way radios and power tools. Ni-CD batteries perform well in the rigorous conditions such as low temperatures, can be re-charged immediately even after long periods of storage, and are economically priced. However, if a battery is not maintained properly (i.e. not fully discharged after each use) it develops a condition known as 'memory effect'.

Nickel Metal Hydride (Ni-MH)
The Nickel Metal Hydride (Ni-MH) battery is a rechargeable battery chemistry that c an be used to replace Ni-CD's in certain applications. Ni-MH shows significant improvements over Ni-CD rechargeable batteries in terms of performance (significantly reduced 'memory effect' when compared with Ni-CD), increased energy density, environmental friendliness, and lighter weight.

Lithium Ion (Li-Ion)
Among the three basic chemistries, this is the most advanced .The Lithium Ion (Li-Ion) battery is a very high energy density rechargeable chemistry, has low self- discharge, and no memory effect .This chemistry is ideal when smaller and lighter weight batteries are required such as c ell phones and laptop computers.

What is Volt?
Volt (V) can be explained as the "Pressure" that is created by the electric source such as a cell phone or two way radios (i.e.: garden hose water pressure).

What is Amperage?
Ampere (Amps) = the "Quantity" of electron flow (i.e.: gallons of water available)

What is millampere -Hours (mAH)?
Volts x Amps = Watts. Usually expressed in milliampere-hours (mAH) when less than 1000 and ampere- hours (AH) when 1.0 or higher. To summarize, 'mAH' can be explained as the 'capacity' of the battery, i.e. the amount of power that is pack ed into the battery. Higher 'mAH' rating results in longer battery life between charges.

What is "Memory Effect"?
Capacity decrease and voltage drop in a battery caused by continuous charging and incomplete discharging. This process causes a battery to hold less charge over time. Ni-CD batteries tend to suffer from memory effect more than the Ni-MH ones. For instance, when a battery is used for a few hours it depletes some of its capacity but say it still leaves around 50% of its capacity intact. If this partially charged battery is re-charged repeatedly without being fully discharged first, it will gradually develop a "memory" that will degrade the capacity to 50% of its true value because of poor battery maintenance.

What is cycle life?
Cycle life is the number of times a battery can be charged and discharged before it runs out of its energy. One cycle is defined as a full charge followed by discharge.

What is self- discharge?
A reversible capacity loss in Ni-CD and Ni-MH batteries; it occurs when the batteries are not in use for extended periods of time. Most batteries loose 1% to 2% of their energy every day, depending on humidity and temperature of the storage place.

What charging precautions should be taken when charging a battery pack?
Clean contacts: To achieve optimum charge contact, be sure both charger and battery contacts are clean. Dirty contacts can result in a charger/battery malfunction.

Optimum charging temperature: Ni-CD batteries are designed to be operated and charged at 65°F. Charging batteries in high temperatures causes the battery to reach a point where the battery discharges, due to faster chemical reactions caused by higher temperatures. Thus a battery never reaches full charge giving 'memory effect'. Conversely, chemical reactions slow with cold ambient temperatures. At cold temperatures, the cells may not be able to accept the charge current. This builds pressure and creates the potential for cell rupture. As a rule, never charge a battery when the ambient temperature is warmer than 120°F or colder than 40°F.

What steps should be followed for the initial charge cycle to maximize battery performance?
All batteries are shipped uncharged. Initially, all new batteries must be charged for 14 - 16 hours continuously. All batteries require a "break-in" period, so don't be alarmed if your battery doesn't hold a full charge right away. A new battery may show false full charge as indicated on your charger. Also the battery may not power up the device because of low voltage.

It is recommended that for the first 5 to 10 cycles one must charge the battery fully and drain it fully before recharging. This will properly condition the battery and will ensure that it will operate at its maximum capacity. This is recommended for all batteries. You can discharge most batteries by unplugging the charger and leaving the battery in the device (e.g. two-way radio) and leaving the device turned on until completely discharged.

What precautions should be taken when storing battery packs?
It is very important that batteries be stored in cool dry places away from heat and metal objects.

How should batteries be charged after they have been in storage (or un-used) for over three months?
It is recommended to use a slow trick le charge for batteries that have been stored for more than 3 months. After the first slow charge, a rapid charge may be us ed.

It is also recommended that periodic battery analyzing and conditioning should be considered to prolong battery life while assuring the battery has enough capacity to run the equipment for the necessary time period.

How often should a battery be replaced?
Batteries are consumable products and therefore they need to be replaced once they no longer generate enough electricity to run the equipment. This can be anywhere from 12 to 18 months depending on the chemistry of the battery.

A Ni-CD battery sometimes can work for more than 12 months if it is us ed properly (refer to Memory Effect). A Nickel Cadmium (Ni-CD) battery should be charged only once if it has been completely discharged. The Ni-CD battery suffers from Memory Effect. The same precaution must be taken for Nickel Metal Hydride (Ni-MH) and Lithium Ion (Li-ON) battery pack s but unlike Nickel Cadmium they do not suffer from Memory Effect. These batteries carry more energy and under normal usage lasts for 12 months. Thereafter the batteries need to be replaced.



Battery Types

Nickel Cadmium (Ni-CD)
Ni-CD (or NiCad) batteries are prone to what's called the "memory affect" They like to be fully drained before being recharged. When they're charged often without being run down first, they develop a "memory" which in time lowers their charge capacity and ultimately reduces their overall life expectancy. They are slightly less expensive than Ni-MH batteries and can be stored for much longer periods of time on a shelf while maintaining a relatively high charge capacity.

Nickel Metal Hydride (Ni-MH)
Ni-MH batteries are not nearly as prone to the "memory affect" and can therefore be charged at any time. They do not get as many charge cycles in their lifetime however, but your long-term battery life might still be better if you typically use Ni-CD batteries and don't wait until the battery has been drained down before recharging. Ni-MH are generally significantly higher in capacity (up to 30% higher per charge than Ni-CD batteries of the same physical size), which means they will last longer per charge, but are not great being stored for periods of time longer than 3-4 weeks . We recommend using Ni-MH batteries when available for agencies that don't have the luxury of running a battery down before recharging (police, fire, EMS, etc.) but NOT as 'emergency backups' that are left on a shelf until they are needed.

NOTE: While Ni-MH batteries *can* be charged in a Ni-CD-ONLY charger, it is not recommended. Ni-MH batteries run very hot, and Ni-CD-ONLY chargers lack the circuitry to shut down charging on a Ni-MH battery, which if left unattended for too long a period of time, the battery could experience melting, venting, bursting or fire. We've never seen it happen with batteries and chargers that were in good condition, but why take that chance. (By the way, we sell multi- chemistry chargers if you're interested)

Lithium-Ion (Li-Ion)
Li-Ion is the newest rechargeable battery chemistry available. Lithium Ion is not affected by the 'Memory Effect'. It can deliver the same capacity and run time in a smaller, lighter pack. The chemistry is mos t popular in cellular and laptop products.

NOTE: If you do not have a charger designed to charge a Li-Ion battery, then Li-Ion is not even an option for you. Your charger MUST specify that it is a tri-chemistry charger or that it can specifically charge Li- Ion batteries.



Also see our Battery Terms