FAQ
What is ‘Active Material’?
Active Material refers to the positive and negative plate pastes that provide energy from a battery when it is discharged. For a lead-acid battery, the positive active material (PAM) is lead dioxide; the negative active material (NAM) is sponge lead.
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How is the capacity of the battery defined?
AMPERE-HOURS = Current (AMPERE) x Time (HOURS) during which current flows from the battery.
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How is the available capacity determined?
The capacity available from the battery is based on its state of charge, rate of discharge, ambient temperature, and specified cut-off voltage.
The electrical energy available from a cell or battery is expressed in AMPERE-HOURS. It refers to the discharge of a constant current in a specified time to a specified cut-off voltage (normally 1.75v/2v per cell) at a specified temperature.
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What is ‘Capacity Recovery’?
Also referred to as recoverable capacity. This is the discharge capacity that can be restored to a cell or battery through various treatments when it has dropped to very low capacity levels.
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What is a ‘Cell’?
The minimum storage unit comprising a battery. The nominal voltage of a Lead-Acid battery is 2.0v. Most batteries are made up of two or more cell groupings. Typically three cells for a 6-volt and six cells for a 12-volt battery.
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What does the charging process entail?
It is the process whereby electrical energy is restored to a single cell or battery while increasing the cell voltage.
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What is meant by ‘Charge Efficiency’?
The ratio of the AMPERE-HOURS delivered during discharge, divided by the AMPERE-HOURS put into the battery during recharge.
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What is the most widely recommended charge method for VRLA batteries?
The constant voltage charge method – this method uses voltage limitation. When the discharged battery is charged in this way, the charge current is reduced automatically according to the state of charge.
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What charge methods uses current limitation?
The constant current charge method - according to the required charge time, a fixed amount of capacity is provided. This charging method requires the presence of certain devices that prevent over charge such as a timer, for VRLA batteries.
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What is ‘Cut-off Voltage’?
It is the final voltage of a cell or battery at the end of charge or discharge.
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What is a ‘Cycle’?
A single charge and discharge of a cell or battery.
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What is ‘Cycle Life’?
The number of cycles a cell or battery provides before failure.
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What is ‘Cycle Use’?
The method of using a secondary battery by charging and discharging.
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What is ‘Deep Discharge’?
The discharge of a cell or battery to 80%-100% of its rated capacity.
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What is meant by ‘Depth of Discharge’?
Frequently expressed as a percentage - it is the amount of capacity removed from a cell or battery during discharge.
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What is meant by ‘Discharge’?
The function of removing current from a cell or battery.
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What is the difference between ‘Discharge Rate’ and ‘Discharge Voltage’?
Discharge Rate: Normally expressed as a fraction of C - it is the rate at which current is taken from a cell or battery. Discharge Voltage: The closed circuit voltage of a battery during discharge.
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What is the difference between ‘Electrode’ and ‘Electrolyte’?
Electrode is the positive or negative plate holding the active materials in a cell while electrolyte conducts ions in the cell. Lead-Acid batteries use a sulphuric acid solution.
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When is a battery on ‘Float Charge’?
When the capacity in a cell or battery is maintained by applying a continuous charge. In this instance, the load is connected to the battery and current is provided from the charger.
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What is ‘Gelled Electrolyte’?
This refers to a type of VRLA cell or battery where the electrolyte is immobilised in a gel made from fumed silica, the gel is then contained within a coarse glass mat, or microporous separator matrix. This gel mat serves as the separator in the VRLA cell in place of the more common glass microfiber material.
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What is ‘High-Rate / Discharge’?
Charge and discharge processes that are carried out at relatively high current densities, with the multiple of C rate depending upon the battery design.
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What is meant by ‘Internal Impedance / Resistance’ and ‘Internal Short Circuit’?
A measure of a cells electrical resistance to current flow, resulting in small or large voltage drops and some level of resistive heating. Impedance (AC) and resistance (DC) values are proportional but different, resulting from differences in measurement methodologies applied. Internal short circuit occurs when positive and negative plates touch inside a cell grouping.
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What is the ‘life’ of the battery?
It is the natural time that a battery/cell reaches when it can no longer deliver the capacity that it was made for, in other words it has lost its characteristics.
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What is a ‘Load’?
A device or mechanism external to a battery, and which is powered by the battery .The resistance of the load and the battery voltage dictate the current flow rate, and thus the run time for the battery.
What is a ‘Maintenance-free’ battery?
Sealed lead-acid batteries, that do not require the maintenance of adding water and have sealed lids to prevent the addition of water, are referred to as sealed lead acid batteries and are thereby termed maintenance free.
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What is the ‘Nominal Voltage’ of a battery?
A nominal value used to indicate the battery voltage; for the sealed lead-acid battery; the nominal voltage is two v/cell.
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What does ‘Open Circuit Voltage’ mean?
The measured voltage of the cell or battery without a load attached.
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Is the battery life reduced by prolonged over-charge?
Yes, the battery life is reduced by prolonged over charge and refers to the continuous charging of a cell after it achieves 100% of capacity.
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What is ‘Over Charge Current’?
The charge current supplied during over charge. Batteries can accept continuous overcharge at recommended rates and temperatures.
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What does ‘Quick Rechargeability’ require?
Quick recharge requires not only good charge acceptability but also safety devices such as thermostats, timers, etc.
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What is ‘Rated Capacity’?
The manufacturers rated capacity of the cell (see capacity).
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What is ‘Refresh Charge’?
The recovery charge, which is done periodically for recovering the lost capacity of batteries due to self-discharge.
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What is a ‘Secondary Battery’?
A battery that can be charged and discharged repeatedly. Example: Lead-acid batteries, Nickel Cadmium batteries.
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Can a battery ‘Self Discharge?’
Yes, a battery may lose capacity while being stored or if not used. The rate of self-discharge is affected by ambient temperature.
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What is the ‘Separator’?
The material separating the electrodes .Used to hold the electrolyte.
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What is ‘Shelf Life’?
The life of a battery when stored in an unused condition.
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What is the method of using secondary batteries in which the battery is constantly charged so that it is always ready for use?
Stand-by use method.
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What does ‘UPS’ stand for?
Uninterruptible power-supply.
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What is ‘Undercharging’ and can it lead to battery failure?
This is a situation where the charge put back into the battery after a discharge is not sufficient to fully charge it, given a certain amount of over charge necessary for the product. It leads to rapid loss of capacity in cyclic duty and on float, using too low a charge voltage can actually result in partial discharge of one or both plates during charge. Because of the tendency to treat them too delicately, undercharging is a common reason for VRLA battery failure.
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What is a ‘Valve Regulated’ cell or battery?
Term for a lead-acid battery employing oxygen recombination technology either glass mat or gelled electrolyte and which contains a pressure-relief valve to vent gases, primarily on overcharge. Common usage acronym is VRLA (Valve-Regulated Lead-Acid) ,formerly known as sealed lead-acid (SLA).
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What is the function of a ‘Vent’ do?
Pressure-relief valve in a cell or battery that allows for the escape of gases at a certain release pressure, but does not allow any level of gas ingress.
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What does ‘VRLA’ stand for?
Valve Regulated Lead-Acid.
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What is a car battery made of?
A car battery is a polypropylene box divided into six partitions or cells that is filled with an electrically conductive sulphuric acid solution called electrolyte. This chemical interacts with the batteries electrodes or metal (lead) plates containing lead and lead oxide, to produce 12 volts of electricity.
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What is the function(s) of a car battery?
The car or starter battery has three functions. First, it provides the initial power to start the engine of a car / truck. Secondly, it keeps itself recharged and generates power when the cars engine is not running. Lastly, it can maintain a low current to power the lights, horn, and other electrical devices for a short period.
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What is ‘Cold Cranking Amperage (CCA)’?
The rating used to define a batteries ability to start an engine in cold temperatures is called COLD CRANKING AMPERAGE (CCA). The CCA of an auto battery is the amount of current a given battery can deliver for 30 seconds at 0 degrees F (-18 ºC) without dropping below 7.2 volts for a 12 volt battery. To find the power of a car battery we multiply the CCA number by 7.2 volts .
For example:
P = IV
P = (600A) (7.2V)
P = 4320 W
Most modern cars require relatively low cranking amps that range from 400 to 600. Sports cars and light trucks require cranking amps ranging from 700 to 1000 A.
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