Power Technology - Batteries
Frequently Asked Questions - BATTERIES:
Types of Batteries and Chemistries – Overview
What is a Battery?
A Battery is a device that converts stored chemical energy into useful electrical energy. It consists of two
electrochemically active electrodes of different composition, both of which are immersed in an electrolyte
that provides a conductive medium between them. When a battery is connected to an outside load, it
provides energy by conveying its internal electrochemical free electrons from the cathode to the anode in
what is known as DC (Direct Current) Voltage. (See battery Types below)
What is battery internal impedance?
Battery internal impedance is the resistance to the current flow inside the battery structure. The older a
battery gets the internal resistance of the battery increases, thus reducing the capacity.
What is the affect of a short circuit on a battery?
Any kinds of conductive material being bridged over the external terminals of a battery will result in a short
circuit. Based on the battery system, a short circuit may have serious consequences, e.g. large current
flash over, rising of the electrolyte temperature or building up internal gas pressure. If the internal gas
pressure value exceeds the limitation of cell cap endurances, the electrolyte will leak, which will
significantly damage the battery and possibly an explosion may occur. Do not short-circuit any battery.
What is Depth of Discharge (DOD)?
Depth of Discharge is used to describe how deeply the battery is discharged, if we say a battery is 100%
fully charged, it means the DOD of this battery is 0%, if we say the DOD of the battery is 20%, which means
battery still has 80% of energy reserved in it. For most of the Lead acid batteries DOD recommended is 50%
and for Lithium batteries 90%. More DOD results in fewer life cycles you can get from that battery.
What is State of Charge (SOC)?
SOC is used to describe how full a battery is. When a battery is fully charged, we can say that the SOC of
this battery is 100%. Lead acid batteries always need to be fully charged for storage. Nickel batteries and
lithium batteries also take SOC to describe energy reserve. The relationship between SOC and DOD is
“SOC = 100% -DOD”
What is an Amp-hour (Ah)?
The Amp-hour is used for describing how much energy that battery can store. The volume of the constant
current (in amps) multiplied by time (in hours) = Amp-hour (Ah) as battery capacity. For example, if a
battery is marked as “12V100Ah/C20”, and you discharge it continuously with current no more than 5A
(may vary battery to battery), this battery will deliver 100Amps in 20hrs. However if you discharge 10A
continuously from the same battery it may deliver only 90Amps (instead of 100Amps) and last only 12hrs.
How to extend the Battery life cycle?
Make sure that batteries are Charged/Discharged under specified conditions as described in the data
sheet. For lead acid batteries (excluding Gel technologies) perform equalization according the battery
manufacturer recommendations. For any batteries, working temperature needs to be taken in to
consideration. If lithium batteries are not fully discharged to 100% DOD the number of cycles could be
effectively extended. Also choosing a good quality charger can improve battery life.
What different battery chemistries are available?
Battery chemistries are divided in to two categories - Primary and Rechargeable.
Primary include technologies like Alkaline (1.5V), LiMnO2 (3V), LiFeS2 (1.5V) and Zinc Chloride (1.5V) which
are non rechargeable.
Rechargeable battery chemistries include NiCd (1.2V), Lead Acid including Flooded, Gel, AGM (2V), NiMH
(1.2V), Lithium Ion (3.6V) and Lithium Ferro Phosphate (3.2V).
What are the advantages and disadvantages of Lead Acid batteries?
Advantages:
Low Maintenance requirements, low self-discharge, no memory and least expensive.
Disadvantages: Cannot be stored in discharged condition, Low energy density, limited number of full
discharge cycles, temperature sensitive, lesser DOD which reduces available energy and
environmental damage.
What are the advantages and disadvantages of Lithium ion batteries?
Advantages:
High energy density, relatively low self-discharge, no memory and low maintenance.
Disadvantages: Subject to transport regulations, requires protection circuit that limits voltage and current,
temperature sensitive and more costly.
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 1 of 10
What are the advantages and disadvantages of NiMH batteries?
Advantages:
Environmental friendly, simple storage and transportation, 30-40% higher capacity over
NiCd, and less prone to memory compared to NiCd.
Disadvantages: Limited service life, limited discharge current, high self discharge, high maintenance and
more costly than NiCd.
What is the advantage of LiFePO4 over Lithium ion?
One important advantage over other Lithium ion chemistries is the superior thermal and chemical stability,
which improves battery safety. Flexible in terms of application and cell design. It has overcharge tolerance
up to 0.7V. Very much higher number of charge/discharge cycles (2000 ~ 3000) and greater DOD (95%)
General - Battery Chemistry:
Because batteries utilize a chemical reaction, battery performance will deteriorate over time even if stored
for a long period of time without being used. In addition, if the various usage conditions such as charge,
discharge, ambient temperature, etc. are not maintained within the specified ranges, the life expectancy
of the battery may be shortened or the device in which the battery is used may be damaged by
electrolyte leakage. If the batteries cannot maintain a charge for long periods of time, even when they
are charged correctly, this may indicate it is time to change the battery.
HEALTH AND SAFETY
The Handling and proper use of batteries is not hazardous provided appropriate facilities are available and users,
having been instructed, are adequately supervised and reasonable care is taken. The following guide is designed
to help indicate potential hazards that may arise and to outline the precautions that should be taken to minimise
such hazards. If an accident should happen each section will cover the correct accident and emergency
procedures. To ensure proper use of your intended battery please read the manual carefully before using it.
Sulphuric Acid (Electrolyte)
Lead acid batteries contain sulphuric acid, which may leak and may be given off as gasses and/or a fine mist
during charging.
Nature of the Hazard
Battery acid is a poisonous and corrosive liquid which will cause burns and irritation to the skin and eyes
and may also burn through clothing.
Precautions
* Always handle batteries with care and keep upright.
* Do not overfill batteries.
* Always charge in a well-ventilated area.
* Always use eye protection and protective clothing where there is any risk of splashes
* Always keep away from children.
Accident and Emergency Treatment
Skin Contact:
Immediately drench the affected area with clean water and remove any contaminated clothing.
If any soreness or irritation persists seek medical advice.
Eye Contact:
Speed of action is vital. Immediately wash out the eyes with clean water for at least 10 minutes
and promptly seek medical attention.
Ingestion:
Do NOT induce vomiting, but make the patient drink as much water or milk as possible and seek
immediate medical attention.
Spillages:
For small spillages, wash away thoroughly with plenty of water.
Disposal:
Suitable acid resistant, labelled containers should be used.
Electrical Energy
Electrical energy can be supplied from batteries and charging equipment.
Nature of the Hazard
Burns may occur from the heating effect on tools and conductive objects in contact with live battery
terminals or conductors. In addition, sparks and molten metal may be ejected and combustible materials
ignited. It is possible to receive a severe electric shock from charging equipment and from a number of
batteries connected in series.
Precautions
Before using conductive tools on a battery, remove metallic personal items from the hands and wrists, i.e.
watches and rings. Disconnect the battery before working on vehicle electrical systems, disconnecting the
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 2 of 10
earth terminal from the battery first and connect it again last. Do not place conductive tools or objects on
top of a battery.
Before using a battery charger, consult manufacturer's literature. Remember to switch the charger off
before connecting or disconnecting a battery.
Accident or Emergency Action & Treatment
Burns: Cool the area with cold water, apply a sterile dressing and seek medical attention.
Electric Shock:
* Immediate action is essential in cases of severe electric shock as the nerves controlling breathing and
heart action may be affected. Do not delay treatment by calling for a doctor: this should be done quickly
if help is available of when the casualty recovers:
* Make sure it is safe to approach. If the casualty is not clear of a live conductor, break the contact. Switch
off the current, remove the plug, or wrench the cable free. If this is not possible, stand on a dry insulating
material (wood, rubber, brick, thickly folded newspaper or a book) and try to push or pull the casualty
clear of contact using similar insulating material as a lever. Do not touch him/her with bare hands.
* If necessary give cardio pulmonary resuscitation.
Emission of Gases:
Hydrogen and oxygen are emitted during charging and can be emitted at other times, particularly if a battery is
moved or shaken. Therefore, always consider that gas is present in the immediate vicinity or at the top of the
battery.
Nature of the Hazard
An explosive atmosphere is created if the concentration of hydrogen in air exceeds 4%.
Precautions
* Always use eye protection where there may be any foreseeable risk.
* Charge in a well ventilated area.
* Avoid sources of ignition close to batteries.
* No smoking.
* No naked flames.
* Always switch off current before making or breaking electrical connection.
* Avoid sparks caused by accidental short circuits.
Accident or Emergency Treatment
Seek any necessary medical attention and remember that any acid may have been ejected.
Be Prepared:
Familiarise yourself with the location of your health care centre and how to contact your doctor, nurse, first
aider or appointed person. Remember to report any accident, involving personal injury, in your official
accident book. If any repair or other work on batteries is contemplated refer to Health and Safety
Regulations. Any additional information, including battery labelling that is provided to cover specific
battery types and applications must be used in conjunction with this guide.
GENERAL CAUTIONS:
To ensure proper use of your intended battery please read the manual carefully before using it.
Handling
Be sure to firstly satisfy yourself as to the suitability for purpose of your batteries
Do not expose to, or dispose of the battery in fire or other heat sources.
Do not put the battery in a charger or equipment with wrong terminals connected.
Avoid shorting the battery
Avoid excessive physical shock or vibration.
Do not disassemble or deform the battery.
Do not immerse in water.
Do not use the battery mixed with other different make, type, or model batteries.
Do not directly solder or pierce the battery
Do not expose to, or leave the battery in very high temperature conditions
Do not use the battery in electrostatic or magnetic environments
Keep out of the reach of children.
Damage causing the mixing the battery positive electrode and cathode can damage the battery.
Charge and discharge
Never attempt to charge a Non-Rechargeable battery
Battery must be charged in appropriate charger only. Never use a modified or damaged charger
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 3 of 10
Do not exceed charge current, voltage or temperature range detailed in this specification.
Do not leave battery in charger over 24 hours.
Do not connect the battery directly to an electrical outlet
If the battery gives off odour, generates heat, becomes discoloured or deformed, or appears abnormal
during use, recharging or storage, immediately remove it from the device and don’t use it.
Keep the terminals clean
Over Discharge: Short excessive discharges charges may not affect battery use, but long excessive
discharges can cause the loss of battery performance and function.
Uses constant electric current and constant voltage charging method. Reverse charges prohibited.
Storage
Lead Acid batteries should be stored in a cool, dry and well-ventilated area. Lithium batteries should be stored
at room temperature, charged to about 30% to 50% of capacity. We recommend that batteries be charged
about once per six months to prevent over discharge. Charge to 30% to 50% before long-term storage.
Weight
Many batteries (Lead Acid) are generally heavy, awkward units to handle and correct lifting techniques
must therefore be used.
Damaged Batteries
Lead acid battery plates consist of lead and its compounds but can only be exposed if a battery is broken
open. In the unlikely event of this happening any spillage should be well damped, swept up and placed in
a suitable acid resistant, labelled container prior to disposal. Normal personal hygiene precautions should
be observed.
Disposal
Batteries, battery cases, battery acid and other battery compounds, must not be burned but must be
disposed of in accordance with the appropriate local legislation. Some used and scrap batteries are
classified as hazardous. For further information the New Zealand Ministry for the Environment have more
advice here: https://www.mfe.govt.nz/publications/waste/safe-disposal-of-batteries/html/
Please consider the environment.
Fire
Because batteries contain combustible materials the Local Fire Authority should be consulted if a large
quantity of batteries are stored together.
Transportation by Road
Battery technologies may subject to the Road Traffic Regulations under ‘Carriage of Dangerous Goods’.
Seek advice here:
http://www.nzta.govt.nz/resources/factsheets/68/dangerous-goods-transported-as-tools-of-trade.html
BATTERY DO’S AND DON’TS
•
Do read the instructions on your device before installing batteries. Make sure to insert the batteries
properly, following the symbols showing you the correct way to position the positive (+) and negative (-)
connections of the batteries (Ends, Tabs, Posts, Leads etc) .
•
Do keep battery contact surfaces clean by gently rubbing with a clean pencil eraser or cloth.
•
Do replace batteries with the size and type specified in the operating instructions. Remove all used
batteries from the device at the same time, and then replace them with new batteries of the same size
and type.
•
Do store batteries in a cool, dry place at normal room temperature. Remove batteries from devices that
will be stored for extended periods.
•
Don't dispose of batteries in a fire, they may rupture or leak.
•
Don't carry loose batteries in a pocket with metal objects like coins, paper clips etc. This will short-circuit the
battery, generating high heat.
•
Don't recharge a battery unless it is specifically marked "rechargeable." Attempting to recharge a normal
battery could result in rupture or leakage.
•
Don't use rechargeable alkaline batteries in nickel metal hydride battery charger.
•
Don't put batteries or battery-powered devices in hot places, elevated temperatures increase the selfdischarge of batteries.
•
Don't mix old and new batteries, or mix different types or makes of batteries. This can cause rupture or
leakage, resulting in personal injury or property damage.
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 4 of 10
CHARACTERSTICS OF THE MOST COMMONLY USED BATTERIES
Battery Technology
Parameter
NiCd
NiMH
Lead Acid
Li-ion
Li-polymer
LiFePO4
Alkaline
Zinc Carbon
Nominal cell
voltage
1.25V
1.25V
2V
3.6V
3.7V
3.2V
1.5V
1.5V
Cycle life
1500
300 ~ 500
200 ~ 300
500 ~ 1000
300 ~ 500
2000 ~ 3000
1
1
Discharge
efficiency
60-85%
66%
50%
90%
90%
90-95%
0%
0%
Charge Time
>1h
2-4h
8-16h
2-4h
2-4h
>2h
-
-
Moderate
Low
High
Very low
Low
Up to 3.6V
-
-
40
80
35
110
100
120
186
36
30 ~ 60days
60 ~ 90days
3 ~ 6 months
-
-
-
-
-
-40 to 60◦C
-20 to 60◦C
-20 to 60◦C
-20 to 60°C
0 to 60◦C
-20 to 60°C
-18 to 55°C
-10 to 50°C
20C
5C
5C
>2C
>2C
2C
-
-
1C
0.5C
0.2C
1C
1C
1C
-
-
Overcharge
Tolerance
Energy density
(Wh/kg)
Maintenance
requirement
Operating
Temperature
Load current
(peak)
Load current
(best result)
Primary Batteries
Alkaline:
Alkaline batteries have higher energy density and longer shelf life compared to Zinc Carbon batteries.
Suitable for most consumer electronic goods such as CD players, digital cameras, toys etc. All cell sizes
including AAA, AA, C, D, 9V. Some Alkaline batteries are designed to recharge but most of them are not.
Li Manganese Dioxide:
Most common consumer grade battery, 80% of the lithium battery market. Belongs to Lithium family where
lithium is used as anode. Suited for low drain, long life and low cost applications. High energy density for
both mass and volume. Cell Terminal voltage 3V. Operating temperature range -30?C to 60?C. High self
discharge at high temperatures. Widely used in commercial/military products for high reliability and pulse
current capability. Available in Coin / Button cells, and cylindrical sizes incl. 1/2AA, A, AA, B, C and D cell.
Li-Iron:
Primary lithium iron batteries have high energy density and long shelf life. They are completely different
from the rechargeable lithium ion batteries. Available in retail and volume packs. This Chemistry is a direct,
high energy replacement for Alkaline in many applications. 1.5V terminal voltage makes this battery the
optimum energy source for the most demanding high current drain electronic goods. Lasts up to 6 times
longer than standard alkaline in digital cameras. Mostly used in smoke alarms, LED lighting and outdoor
devices. Available in AA and AAA size.
Rechargeable Batteries
Li Ferro phosphate or Lithium Iron Phosphate:
Mainly used in high power applications. The safest of the lithium rechargeable batteries with outstanding
cycle life, good energy density and excellent power density. LiFePO4 offers light weight and the best
repeatable, stable high-temperature performance of the lithium chemistries. It offers a very high number of
charge/discharge cycles and very low DOD capability. Applications include portable Power Tools,
electronics and EV. The technology is an ideal lightweight Lead Acid replacement. LiFePO4 has the cell
voltage of 3.2V.
Li – Ion:
Higher energy density available from a rechargeable battery and a cell terminal voltage of 3.6V make this
chemistry the industry standard for modern electronic goods. Li-Ion offers small size and light weight power
for portable devices. Beyond consumer electronics, they also are growing popularity in military, electric
vehicle and aerospace applications. Lithium ion batteries can be dangerous under high temperature/over
charge conditions and can pose a safety hazard. They come in different shapes small cylindrical, large
cylindrical, pouch and prismatic. The absence of case gives pouch cells the highest energy density;
however batteries using pouch and prismatic cells require an external means of containment to prevent
expansion when their SOC level is high. Always make sure that these batteries have and use a PCB
(protection circuit board).
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 5 of 10
Li – Polymer:
Offers similar energy density to Li-Ion chemistry in a thinner form factor for slim line digital electronic goods.
Available in a huge range of different sizes. High pulse current capability as well as lowest self-discharge
makes this battery ideal for designs with a high standby/pulse current ratio. Very sensitive to high
temperatures. Can explode and catch fire if misused or defective. Always use PCB (protection circuit
board) with these batteries.
Ni-Cd:
Widest temperature range tolerance for rechargeable technology. Ni-Cd has a terminal voltage of 1.2V
which will decrease little until nearly the end of discharge. Lower energy density/unit volume, however NiCd offers the advantage of providing maximum available power into near short circuit loads, at low cost.
Cell sizes include AA, C, D etc.
This technology is beaten by NiMH and Li-ion batteries. Ni-Cd suffers from memory effect if they are
discharged and recharged to the same state of charge hundreds of times. They contain 6-18% of
cadmium so need to be disposed of at a battery disposal facility.
Ni MH:
NiMH chemistry is the next step in Nickel based batteries, boasting higher energy density and no memory
effect resulting in an affordable, longer life, more durable solution for applications suited to 1.2V
rechargeable cells. It is advisable to charge the NiMH with a smart battery charger to avoid over charging.
A NiCd charger should not be used as a substitute for an automatic NiMH charger. The simplest way to
safely charge a NiMH is with a fixed low current. Also over discharging can result in one or more cells going
in to polarity reversal, which can cause permanent damage to the cells. As there is no toxic cadmium in
NiMH, disposal poses less environmental hazard.
Lithium Thionyl Chloride: (Li/SOCl2)
They are a superior power source, combining the highest energy density and voltage, longest service life
and lowest self-discharge. Suitable for low temperature applications. Operating temperature ranges from –
55°C to 85°C. They are most used in portable electronics, memory backup and military applications. Can
explode if short-circuited. Has relatively high energy density about 500Wh/kg. Operating voltage is 3.6V.
They offer very low self discharge, 1% per annum, and come in different sizes and shapes including AA,
1/2AA, 2/3AA, C, D, DD, BEL etc.
Applications: This list represents actual application where Tadiran lithium cells and batteries are already
being used as a main backup source of energy:
* Utility meters and A.M.R equipment.
* PC, computers and data loggers.
* CMOS memory and RTC backup.
* Toll tags and RFID transponders.
* Programmable logic controllers.
* Wireless alarm sensors.
* Sea buoys and remote monitoring systems.
Lead Acid:
The most common battery used as they are less expensive than the other battery technologies. They are
used in wider applications like marine, renewable, power systems etc. High energy density/unit volume
but has a greater mass. Very well suited to standby power applications where reliability is a must. A robust
power solution typically available in 2V, 6V and 12V at capacities ranging from 1.2A/h up to 1000’s of A/h.
They come in different varieties such as starting batteries, deep cycle batteries and low/high charge and
discharge batteries. They do come in maintenance free designs, Gel and AGM. Lead acid batteries lose
the ability to accept charge when discharged for too long due to sulfation. Never ever store the lead acid
batteries discharged. To maintain the health of these batteries they need be charged regularly and
equalize (excluding Gel cells) ever 60-90 days. Self discharge rate per month will be approximately 3%.
A Deep-Cycle battery is a lead-acid battery, designed to be regularly deeply discharged using most of its
capacity. Start batteries are designed to deliver short, high-current bursts for engine cranking, frequently
discharging only a small part of their capacity. A deep-cycle battery is designed to discharge between
45% and 75% of its capacity, depending on the manufacturer and the construction of the battery.
Although these batteries can be cycled down to 20% charge, the best lifespan vs cost method is to keep
the average cycle at about 45% discharge. There is a direct correlation between the depth of discharge
of the battery, and the number of charge and discharge cycles it can perform. Both of these types may
be referred to as Flooded. (abridged source Wikipedia)
A VRLA battery or SLA (valve-regulated lead–acid battery), more commonly known as a Sealed battery or
Maintenance free battery, is a type of lead–acid rechargeable battery. Due to their construction, they do
not require ventilation, can be mounted in any orientation, and do not require constant maintenance. The
reduced venting is an advantage since they can be used in confined or poorly ventilated spaces. They
are widely used in large portable electrical devices, off-grid power systems and similar roles, where large
amounts of storage are needed at a lower cost than other low-maintenance technologies like li-ion.
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 6 of 10
There are two primary types of VRLA batteries, GEL cells and AGM. Gel cells add silica dust to the
electrolyte, forming a thick putty-like gel. These are sometimes referred to as "silicone batteries". AGM,
(Absorbed Glass Mat), batteries differ from flooded lead acid batteries in that the electrolyte is held in the
glass mats, not freely flooding the plates. Very thin fibreglass mesh increases surface area enough to hold
sufficient electrolyte on the cells for their lifetime. The fibers that compose the fine glass mat do not absorb
nor are they affected by the acidic electrolyte. AGM batteries, both deep cycle and starting, are built in a
rectangular case to BCI battery code specifications. Both designs offer advantages and disadvantages
compared to conventional batteries, as well as each other. (abridged source Wikipedia)
BATTERY GLOSSARY
* AGM (Absorbent Glass Mat) battery: A lead acid battery using a glass mat to promote recombination of the
gases produced by the charging process.
* Ampere-hours (AH): The energy drawn from a battery in one hour. (A current of 1A for one hour = 1Ah.)
* Anode: The electrode on which oxidation occurs is called the anode; it releases electrons. When applying power
to a device (vacuum tube, diode, battery on charge), the anode is positive; withdrawing power on discharge
makes the anode negative. In a device that consumes power (charge), the anode of a battery is positive; a
device that provides power (discharge), the anode is negative.
* Battery: Electrochemical cell, or cells, connected in series (some may be in parallel). A battery is composed of the
anode (negative electrode), cathode (positive electrode), separator and electrolyte as catalyst.
* Battery cycle: Full charge, followed by a full discharge and recharge. No standard exists as to what level the
battery needs to be discharged to constitute a cycle.
* Battery Management System (BMS): System inside or outside of a battery to manage charge and discharge, as
well as report state-of-function; BMS is an important part of hybrid and electric cars, satellites and electronic
equipment. Some batteries use a PCM to protect the battery and manage the charging.
* Button cell: Miniaturized battery also known as coin cell. Most are non-rechargeable.
* Capacity: Electrical energy of a battery as expressed in ampere-hours (Ah). The energy is measured by observing
the elapsed time while discharging a battery at a constant current to the specified end-of-discharge voltage.
* Capacity offset: Capacity correction when discharging a battery under a higher or lower C-rate than specified.
For example, a lead acid battery produces a higher capacity if discharged at a 20-hour rate than at 5-hour rate.
* Cathode: Electrode in an electrochemical cell in which reduction takes place, absorbing electrons. During
discharge the positive electrode of the cell is the cathode. During charge the situation reverses and the negative
electrode of the cell is the cathode. In a discharging battery, the cathode refers to the positive electrode.
* C-code: Abbreviation of “configuration code” defining the battery parameters; C-code is stored in a battery
adapter and configures the analyzer to the correct battery settings (Cadex systems).
* Cell:
* Cell mismatch: Cells within a battery pack that have different capacities, voltages or resistive values. Differences
in capacity are most common.
* Cell reversal: During deep discharge, the strong cells apply a reverse polarity across a depleted cell when
discharging too low. Cell reversal can damage the cell.
* Charge: Replenishing electrical charge to a cell or battery.
* Cobalt (Co): Hard, lustrous, gray metal with atomic number 27; used for batteries, preparation of magnets, and
high-strength alloys.
* Coulomb: Unit of electric charge. One coulomb (1C) is equal to 1 ampere in 1 second.
* C-rate: Unit by which charge and discharge times are scaled. At 1C, the battery charges and discharges at a
current that is at par with the marked Ah. For example, 1C charges and discharges a 2Ah battery at 2A; 0.5C at 1A
and 0.25C at 0.5A.
* Current-limiting charger: Charging occurs by keeping the current constant and allowing the voltage to fluctuate
(typically used on NiCd and NiMH chargers).
* Cycle: Charge/discharge/charge of a rechargeable battery. No standard exists as to what depth of discharge
(DOD) constitutes a cycle.
* Cycle life: Number of cycles before a battery is no longer usable. (A battery is considered non-usable if the
delivered capacity of a fully charged battery falls to 60–80 percent; the application specifies the capacity
threshold.)
* Cylindrical cell: Positive and negative plates are rolled up and placed into a cylindrical container.
* DC: Direct current; current flows in one direction. A battery delivers a DC current.
* DC-to-DC converter: A converter that transforms a direct current (DC) voltage to a higher or lower potential.
* Delta Temperature over delta time (dT/dt): Senses the rate of temperature increase over time rather than
measuring the absolute temperature to detect the full charge state of a battery.
* DOD: Depth of discharge; 100 percent DOD is full discharge; 80 percent DOD is commonly used for specification.
No standard exists as to what DOD constitutes a cycle.
* Dumb battery: Battery containing no electronic intelligence with which to communicate.
* Electrochemical impedance spectroscopy (EIS): Method to test the electrochemical characteristics of a battery;
EIS injects AC signals at different frequencies and analyzes the response.
* Electrode: Conducting element within a cell in which an electrochemical reaction occurs.
* Electrolyte: Non-metallic conductor of electricity (typically liquid) placed between positive and negative
electrodes of a battery. Physical movement of ions enables current flow.
* Energy: The work a physical system is capable of performing over time. In electrical terms, multiplying voltage
times current overtime equals Watt-hours (WH). Energy is also given in joules (J); 1,000 joules are 0.277Wh.
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 7 of 10
* Energy density: Also known as volumetric energy density; indicates the amount of energy a cell can contain in
volume (WH/l). The energy density is synonymous with the runtime of a battery.
* Energy Star: An organization that promotes energy efficiency. Some countries mandate meeting the Energy Star
requirements.
* Exercise: Commonly understood as one or several discharge cycles to the end-of-discharge voltage threshold
with subsequent recharge. Used to maintain NiCd and NiMH batteries.
* Fast charge: Typical fast charge time is 1–3 hours; charger detects full state-of-charge and switches to trickle
charge (nickel- and lead-based) or disconnects from any charge (Li-ion).
* Float charge: Similar to trickle charge. Compensates for the self-discharge of a lead acid battery.
* Frequency: In battery context - Frequency indicates how many times the voltage potential changes from positive
and negative per second, or how many times a battery is being cycled in a given time.
* Fuel cell: Device that converts oxygen and hydrogen into electricity and water.
* Fuel gauge: State-of-charge (SOC) indicator estimates the remaining charge of a battery.
* Fuzzy logic: A form of multi-valued, mathematical logic derived from a range of blurred data to deal with
reasoning that is approximate rather than precise. Battery rapid testing, image recognition and weather
forecasting use fuzzy logic.
* Gravimetric energy density: Also known as specific energy; indicates the amount of energy a cell can contain in
weight (WH/kg). The gravimetric energy density is synonymous with the runtime of a battery.
* Hertz (Hz): Unit of frequency; 1 Hz constitutes one full cycle per second.
* Hydrogen (H): A chemical element with atomic number 1. Hydrogen is the lightest and most abundant chemical
element, constituting roughly 75 % of the universe's elemental mass.
* Hydrometer: Device used to measure the specific gravity of a fluid; reads state-of-charge of lead acid and other
flooded batteries.
* Hysteresis charge: Chargers turns off at full charge; a periodic recharge compensates for the self-discharge.
* Imaginary impedance: Also known as complex impedance, the imaginary impedance is the electrical resistance
of reactive components that changes with frequency. The capacitive resistance decreases with rising frequency
and the inductance resistance increases.
* Impedance: Combination of capacitive, inductive and pure ohmic resistance; applies to battery and other
reactive devices. Impedance is measured in ohms (R) and is frequency dependent.
* Intelligent battery: Also known as a “smart” battery; contains circuitry to enable communication between the
battery, application, charger and user.
* Internal resistance: Electrical resistance of a battery pack given in milliohms. A good battery that is fully charged
has a low resistance; an aged or empty battery has a higher resistance.
* Intrinsically safe battery: Battery with built-in protection circuitry to allow safe operation in a hazardous area.
Electronic circuit prevents sparks by limiting voltage and current peaks.
* Ion: Atom or molecule with unequal number of electrons and protons; provides a positive or negative electrical
charge.
* Joule (J): Measure of energy or cell capacity. For electrical energy, 1 joule is 1 amp at 1 volt for 1 second, or one
watt-second; 1Wh = 3.6kJ; 1,000 joules = 0.277Wh; also applies to mechanical energy..
* Lead acid battery: Rechargeable battery in flooded and sealed versions; has a low specific energy and is
commonly used for various EV and stationary applications, Security systems, Power Systems and UPS.
* Lithium (Li): Soft, silver-White metal belonging to the alkali metal group with atomic number 3. Lithium is the
lightest metal and the least dense in the element family.
* Lithium battery: Battery using lithium metal on the anode. Most lithium batteries are non-rechargeable.
* Lithium-ion battery: Rechargeable battery with graphite anode; the cathode consists of cobalt, manganesenickel phosphate, or a combination thereof. Other anode materials are being tried.
* Lithium-ion Polymer battery: Rechargeable battery similar to Li-ion with a solid polymer as electrolyte; addition of
gelled conductive material promotes conductivity.
* Lithium Polymer battery: Rechargeable battery using solid polymer as electrolyte; requires heat to promote
conductivity.
* Load current: Current draw when applying an electrical load.
* Manganese (Mn): Chemical element with atomic number 25. Manganese is used in combination with iron and
other minerals in steelmaking and fabrication of Li-ion batteries.
* Matrix: In batteries, a matrix serves as a reference to estimate characteristics, such as capacity.
* Memory: In nickel-based batteries, memory relates to reversible capacity loss. The modern definition of memory
refers to crystalline formation.
* Milliampere-hour (mAh): Specifies battery capacity or rating; 1000mAh equals 1Ah.
* NCA: Lithium-ion battery made of nickel-cobalt-aluminium.
* Negative delta V (NDV): Drop in battery voltage When a sealed NiCd or NiMH battery reaches full charge; NDV
detects full charge on nickel-based batteries in chargers.
* Nickel-cadmium battery (NiCd): Rechargeable battery using cadmium on the anode and nickel on the
cathode; the electrolyte is alkaline-potassium-hydroxide.
* Nickel-hydrogen battery (NiH): Rechargeable battery commonly used for space applications; uses pressure
vessels to contain the hydrogen.
* Nickel-metal-hydride battery (NiMH): Similar to nickel-cadmium; the anode is made of a hydride alloy that is less
toxic than the cadmium of NiCd; offers 30 percent more capacity than NiCd but is less durable.
* NMC: Lithium-ion battery made of one-third nickel, one-third manganese and one-third cobalt or similar
combinations.
* Nominal voltage: Refers to the accepted standard of a terminal voltage. The nominal voltage of NiCd is 1.20 or
1.25V/cell; Li-ion can be 3.6 or 3.7V/cell; and LiFePO4 3.2V/cell.
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 8 of 10
* Ohmic resistance: Pure electrical DC resistance without capacitive and inductive reactance.
* Ohm test: Internal resistance measurement of a battery using pulse method.
* Organic: Relating or belonging to chemical compounds having a carbon base.
* Overcharge: Exceeding the full charge acceptance of a battery. The battery heats up and produces gases.
* Parasitic load: In electrical terms, power consumption when an appliance is turned off.
* Passivation layer: Resistive layer that forms in some cells after prolonged storage. The passivation layer must be
broken to enable proper operation; applying a charge/discharge may do this.
* Peukert law: Reflects internal resistance and recovery of lead acid and other battery chemistries. A low reading
close to one (1) indicates a well-performing battery with minimal losses.
* Phosphate: A salt or phosphoric acid.
* Polarisation: Electrical potential reduction of electrodes typically arising from prolonged or rapid discharge of the
battery.
* Polymer: Electrical insulator that passes ions.
* Pouch cell: Cell packaged into a flexible, heat-sealable foil pouch.
* Power: Transferable power. In electrical terms, multiplying voltage times current equals power in watts (W). Power
is also given in horsepower (1hp = 746W). Power over time is energy in Wh or joule.
* Power density: Also known as volumetric power density; reflects the loading capability or the amount of current
the battery can deliver. Power density is synonymous with power delivery; readings are in Wh/l.
* Power factor: Ratio of real power to apparent power. The unity power factor of 1.00 delivers 100 percent of the
current to a load; a power factor of 0.50 reduces the contribution to 50 percent. A purely resistive load (heater
elements) has a unity power factor; purely capacitive or inductive loads have zero pf. (refers to AC systems)
* Primary battery: Non-rechargeable battery.
* Prismatic cell: A battery in which the positive and negative plates are stacked instead of rolled.
* Protection circuit: Electronic circuit built into a battery pack to maintain safe operation of a battery and
equipment when improperly handled.
* Quick charger: Charger that charges a battery in 3–6 hours, also may be termed Rapid Charge
* Reactance: Presence of inductive and capacitive resistance; the reading is frequency dependent.
* Recondition: Secondary discharge applied below the 1.0V/cell cut-off threshold of a nickel-based battery; helps
break down crystalline formation (memory).
* Reformer: A device that extracts hydrogen from fossil and other fuels. The catalytic reaction of a reformer
separates the hydrogen from the carbon in a fuel and mixes the carbon to form carbon dioxide that is released
into the atmosphere.
* Residual capacity: Remaining battery capacity when a portable device cuts off, or capacity prior to charge.
* Resistance: Electrical resistance is a restriction of current flow. Batteries with high internal resistance are unable to
deliver high currents on demand; resistance generates voltage drop and heat.
* Reverse load charge: Charge method interspersing discharge pulses between charge pulses to promote the
recombination of gases generated during fast charge; helps reduce memory.
* Runtime: The length of time a battery can provide power with a charge.
* Secondary battery: Rechargeable battery.
* Self-discharge: Capacity loss during storage due to internal leakage between the positive and negative plates in
a cell.
* Silver-zinc: Rechargeable battery with high specific energy; used for defence and aerospace applications, as
well as professional TV cameras; battery is expensive and has a short cycle life.
* Single Wire Bus: Simplified “smart” battery using only one wire for digital communications.
* Slow charge: Overnight charge lasting 10–16 hours at a charge current of 0.1C.
* Smart battery: Also known as an “intelligent” battery; pack contains intelligence to communicate between
battery, equipment, charger and user.
* SMBus: System Management Bus is a two-wire interface that communicates with the battery and device by
accepting control parameters and providing battery status, such as state-of-charge, manufacturer information,
cycle count and error messages.
* Sodium-nickel-chloride: A further development of sodium-sulphur battery. Zeolite Battery Research Africa Project
(ZEBRA) made the battery commercially viable; needs heat for operation, used for large UPS and EVs.
* Sodium–sulphur (NaS): Gained attention in 1970s and 1980s; battery has a short service life and high
manufacturing costs. The sodium-nickel-chloride battery (ZEBRA) is its successful replacement.
* Soft cell: High cell resistance causes the applied voltage to rise above a defined level during charge and drops
low on a load. Cold temperature or lack of electrolyte causes the soft cell condition.
* Specific energy: Also known as gravimetric energy density; indicates the amount of energy a cell can contain in
weight (Wh/kg). Specific energy (capacity) is synonymous with the runtime of a battery.
* Specific gravity (SG): Weight ratio of a chemical solution compared to water at a specified temperature. The SG
of water is 1.0; the electrolyte of a fully charged lead acid battery is about 1.30.
* Specific power: Also known as gravimetric power density; reflects the loading capability or the amount of current
the battery can deliver. Specific power is synonymous with power delivery; readings are in Wh/kg.
* Spinel: A hard glassy mineral consisting of an oxide of magnesium and aluminium that forms a three-dimensional
chemical structure. Manganese-based Li-ion consists of a spinel structure.
* State-of-charge (SOC): Indicates the maximum charge a battery can hold. A fully charged battery has 100
percent SOC; one that is at the half way point has 50 percent and an empty pack has zero SOC.
* State-of-function (SOF): Reflects battery readiness; includes capacity, ability to deliver current (internal
resistance), voltage, self-discharge, charge acceptance and SOC. A battery that meets manufacturer’s
specifications has an SOF of 100 percent; performance degradation lowers the reading.
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
www.powertech.co.nz
Page 9 of 10
* State-of-health (SOH): Reflects performance; includes capacity, ability to deliver current (internal resistance),
voltage, self-discharge and charge acceptance. A battery that meets manufacturer’s specifications has a SOH of
100 percent; capacity loss and other anomalies lower the readings. SOH excludes SOC.
* Sulfation: Lead sulphate crystal formation in a lead acid battery that inhibits current flow, caused by storage at
low state-of-charge.
* Super capacitor: Also known as an ultra capacitor or double layer capacitor, the super capacitor is an
electrochemical capacitor that can charge and discharge quickly. The specific energy is about one-tenth that of
lithium-ion but has a high cycle life and performs well at cold temperatures.
* System Management Bus (SMBus): Protocol for “smart” battery.
* Thermal runaway: Uncontrolled disintegration of a battery from inside out; can be caused by cell defect,
overcharging, excess heat and other abusive conditions.
* Titanate: Substance used for anode material of some lithium-based batteries.
* Trickle charge: Small charge to compensate for the self-discharge of a battery.
* UL1642: A safety acceptance test for lithium-based batteries mandated by Underwriters Laboratories. Other
commonly used approval norm is IEC62133.
* Universal Serial Bus (USB): The USB port is a bi-directional data port featuring a 5-volt supply and two data lines to
accommodate auxiliary devices such as memory sticks, keyboards, mice, wireless interfaces, cameras, MP3 players
and battery chargers.
* Valve-regulated lead acid (VRLA): Maintenance-free lead acid battery for uninterruptible power supply systems
(UPS); recombines oxygen (positive plate) with hydrogen (negative plate) during charge; valves regulate cell
pressure through release of gases.
* Voltage (V): Electric energy potential per unit charge. One volt = 1 joule per second (1,000 joules = 0.277Wh).
* Voltage delay: During prolonged storage, some battery systems develop a passivation film on the surface of the
active material, delivering a momentarily lower voltage until the film dissipates through discharge.
* Voltage limit: Set threshold on charge and discharge of a battery.
* Voltage-limiting charger: Charging occurs by limiting the battery voltage at a maximum charge level and
allowing current to fluctuate (typically used on lead acid and Li-ion chargers).
* Volumetric energy density: Also known as energy density; indicates the amount of energy a cell can contain in
volume (Wh/l). The volumetric energy density is synonymous with the runtime of a battery.
* Watt (W): Unit of power; ampere (A) times volt (V) equals watts (W).
* Watt-hour (Wh): Unit of power in one hour. Multiplying the nominal battery voltage (V) by the rated capacity (Ah)
gives the battery energy in Wh. Example: 14.4V by 2.5A = 36Wh.
* Zapping: Applying a momentary high-current pulse to a battery to evaporate a short. Zapping is said to improve
new NiCd batteries.
Researched and compiled by
Suresh Ponnam BEng-Electronics & Comms PG Dip.lapps Dip BM Applications and Design Engineer - Power Technology
Power Technology - Frequently Asked Questions – Batteries ©2014
+64-9-8366744
2014
www.powertech.co.nz
Page 10 of 10