Virtual Mechanic

Protecting The Environment And Preserving Resources

Recently, business and individuals alike have all become more aware of the need to make every effort to protect our environment and preserve the earth’s vital resources.  History has shown that a number of products and practices that were taken for granted eventually proved to be of major concern to the future of the planet.  For example, air-conditioning and refrigeration contributed greatly to health and comfort the world over, yet escaped CFC’s are said to be damaging the earth’s protective ozone layer, creating a serious global problem.  Batteries need to be considered in a similar light.  While they are a necessary part of everyday living and vital to our way of life, they also represent a major challenge in terms of their environmental impact.

The car battery under your car bonnet contains around 10 kilos of lead, 4 litres of electrolyte, of which about one third is sulphuric acid, and about 1 kilo of durable plastic.  In other words, it’s bulky, it’s heavy and all of its components are either hazardous to humans and the environment or non biodegradable.

Now, the challenge for the battery industry is to harness the same technological ingenuity that has served us in the past to provide the answers for the environmental dilemmas facing us today and tomorrow.  Now, turning the environmental challenges of recycling batteries into opportunities is good business.

GNB Battery Technologies have led the way with the introduction of  ‘Total Battery Management’. It’s a great example of post-consumer recycling in which components of a consumer product – after its usefulness is exhausted – are recycled right back into more of the same product.

Taking care of problems in our own backyard
Based on recent surveys, it is estimated that throughout Australia there are about 1.4 million spent batteries lying in gardens and garages.  Acid spillages from these batteries are potentially dangerous to humans and can also pollute the ground itself.  Acid spillages onto the ground will contaminate soil, while in the case of concrete, acid spillage will cause severe damage.

So how do you get rid of it?  The answer is not to get rid of it, but to recycle it.  If spent batteries are just dumped they cause several problems.  Not only do they add volume to the ever growing landfills, but they represent a considerable environmental danger as the cases eventually deteriorate, crack and leak dangerous acids.  While recycling batteries has no easy or ready made solution, it is one that is a major priority if we are to make our environment a healthier and safer place for future generations.

Already, batteries lead the way in recycling terms, and unlikely as it first might seem, the percentage of batteries recycled is well ahead of paper, glass and aluminium.

Because the earth’s resources are not infinite it is becoming increasingly important to continue developing more efficient methods of recovering and recycling batteries.  This will enable us to rely less and less on having to mine the earth for the raw materials need to manufacture new batteries, placing less demands on existing resources and reducing the possible environmental concerns that may confront us in the future.

Simply following these steps when disposing of batteries will go a long way to protecting our environment and our future.

· Do not put them in household garbage
· Do not leave them around the home
· Do not throw them in the tip

Instead, they should be returned to:
· a retailer when making a battery purchase
· a service station or auto electrician
· a scrap metal merchant
· a GNB outlet

You can play your part in helping the environment by returning old batteries.  At the same time you’ll also be helping to keep the cost of new batteries down by reducing manufacturing costs.

· The same transportation network that distributes new batteries also takes responsibility for safely picking up spent batteries and trucking them from the point of exchange to GNB recycling plants which begin the resource recovery process.  Batteries are broken up and recyclable components are recovered.
· Plastic pellets recovered from old cases and covers are used to manufacture new battery cases and covers.
· Lead ingot recycled from old plates and lead oxide materials are used to manufacture new battery grids and lead oxide plate material.
· Sodium sulphate crystals chemically separated from old battery acid are recycled and sold to other industries as raw material for detergents, textiles and glass.

Battery Recycling

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia ©2009

· Check batteries for obvious damage such as cracked or broken cases, terminal damage or broken electrical leads.
· Check that the battery is secure in its compartment.  Tighten hold-down clamps if necessary.
· Check that the alternator drive belt is not loose and tighten if necessary.
· Check the vehicle charging system by starting the engine and adjust the engine revs to approximately half the normal throttle opening, then measure the battery voltage after is has stabilised.
· It should read between 14.1 and 14.4 volts to maintain the battery correctly.  If it reads less than 14.0 volts or more than 14.5 volts the regulator is faulty and will cause battery failure in time due to improper charging.  An auto electrician is needed to rectify this problem.
· Make sure that the top of the battery is clean.  Wash with a diluted solution of bicarbonate of soda and wipe dry with a clean cloth.
· Make sure the battery terminals and cable connections are clean and tight.  Coat terminals with Vaseline or petroleum jelly to stop corrosion.
· If the battery has removable vent caps, check the specific gravity of each cell with a hydrometer.  A good battery should have a specific gravity of 1240 or higher in all cells. Ifs the specific gravity is even in all cells but reads below 1220 the battery is probably serviceable but needs to be recharged.  If one or two cells are significantly lower in specific gravity reading than the others, the battery is suspect and could fail at any time.  Recharge the battery and carry out a load test to verify the battery’s condition.
· If the electrolyte level is low, top up each cell with distilled or deionised water to approximately 12mm above the top of the plates, then charge the battery.
· Check the open circuit of the battery with an accurate digital voltmeter.  Conventional low maintenance batteries should read 12.4 volts or higher and sealed maintenance free batteries should read 12.5 volts or higher.  If the reading is below these cut-off levels, the battery needs to be charged and then load tested to confirm whether it is faulty or not.
· Charge rates for various battery types are available from the manufacturer or your nearest battery service agent.
· Carry out load test to see if the battery is serviceable.

HRD testers are available as either fixed or variable load testers.  Operating instructions and procedures may vary from brand to brand.  The following procedures are indicative only.  When available, the manufacturer’s instructions should be followed.

Using a fixed load HRD tester
· Attach tester clamps to battery terminals in correct polarity (usually red to positive [+ve] and black to negative [-ve] ).
· Set selector switches on load tester to appropriate battery range.
· Apply load test for 10 seconds.
· Read load tester.
· If voltage is at or above the minimum voltage specified by the tester manufacturer then the battery is not faulty, and should be recharged and returned to service.
· If the voltage on load is below the minimum voltage specified by the tester manufacturer the battery is fault and should be replaced.

Using a variable load HRD tester
· Attach tester to battery terminals (usually red to positive [+ve] and black to negative [-ve] ).
· Set selector on load tester to 50% SAE cranking current or 3 times the 20 hour rate if SAE current is not known.
· Apply load test for 10 seconds.
· Read load tester.
· If the voltage is at or above 9.6 volts, then the batter is not faulty, should be recharged and returned to service.
· If the voltage on load is 9.5 volts or below, the battery is faulty and should be replaced.
Recommended Equipment

Battery Testers
For repeated operation:
 DURST 2003F
 6V/12V/24V, heavy duty carbon pile resistor, fan cooled, current up to 500 Amps
 DURST 3006
 6V/12V/24V, heavy duty carbon pile resistor, fan cooled, current up to 1000 Amps
 CHRISTIE CT800
 6V/12V, heavy duty carbon pile resistor, fan cooled, current up to 800 Amps
 For individual operation (not repeated tests).
 CHRISTIE BT900
 Fixed load tester 300 Amps for testing 12 volt batteries up to 900 CCA
 (Note: this machine cannot test 6 volt batteries).

Digital Voltmeters
Wattmaster KD567

Hydrometer
Use a good quality unit

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia ©2009

Warning
Extreme care must be taken when jump starting an engine or serious bodily injury or damage to the vehicles may result.

If jump starting is not done correctly, expensive damage can be done to a vehicle’s electrical system, particularly to those fitted with electronic ignitions.  Check the vehicle operating manual, if there are no specific instructions, then follow these steps.
When jump started, flat batteries generate high volumes of hydrogen gas which is extremely explosive, so sparks and naked flames must be avoided at all times.  Do not lean over batteries during the operation.  As a precaution, wear safety goggles and a face shield to protect eyes.
First, check to ensure both batteries are the same voltage (6 or 12 volt) and that the two vehicles are not touching each other.  If the failed battery is open circuit do not attempt to jump start.

* Open circuit batteries can be detected by:
· battery volts reading zero immediately after a high rate discharge test is applied.
· when the battery will not accept charge current.

Carefully follow these steps in order:
Step 1
Warning: Jump starting can damage vehicle electronics.  Check the vehicle operating manual.  If there is no specific instructions then follow these steps.  If the failed battery is open circuit* do not attempt to jump start.

Step 2
· Be sure the batteries of both cars are the same voltage (6 volt or 12 volt).
· Drive the donor car close to the disabled car but ensure that the vehicles are not touching.
· Place both cars in neutral or park and apply hand brake.
Make sure both vehicle ignitions are switched to OFF and all electrical equipment is OFF.

Step 3
Connect the vehicles in the following EXACT sequence and make sure the jumper leads are clear of any moving parts.
· Take the RED jumper lead and connect to POSITIVE terminal (marked + or POS) of the discharged battery.
· Connect the other end of the RED jumper lead to the positive terminal of the charged battery.
· Take the BLACK jumper lead and connect one end to the NEGATIVE terminal (marked – or NEG) of the charged battery.
· Make the final connection to the engine block or chassis of the stalled vehicle (negative earth vehicles only).  Never use Air Conditioner, Brakes or Fuel Lines for engine earth.

Step 4
Start the engine of the stalled vehicle.

Step 5
After starting, allow engine of the stalled vehicle to fast idle for a minimum of 10 minutes before disconnecting the jumper leads (see step 6) to allow the cars electrical systems to balance.  This reduces the possibility of damage to vehicle electronics.

Step 6
Remove the BLACK cable first from the vehicle with the discharged battery then the opposite end from the charged battery.  Repeat for the RED cable.

Step 7
After your car has been jump started, the battery should be recharged with a battery charger.

 
This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia ©2009

Keep batteries topped up
Maintaining a sufficient electrolyte level ensures the electrolyte is neither too high or too low.  Use distilled or deionised water and never over fill.

Maintenance free batteries do not require topping up and are fully sealed to resist tampering.  Low maintenance batteries require the addition of water only once per year.

Keep batteries clean and dry
Dirt on a battery’s surface leads to discharge and corrosion.  Avoid spilling oil or grease onto the top of the battery.  To remove dirt or moisture, wash with a solution of bicarbonate of soda and water.  Rinse afterwards with clear water.  Ensure vent plugs are in place at all times.

Check electrical connections
Make sure battery terminals and cable connections are clean and tight.  Coat terminals with Vaseline or petroleum jelly to stop corrosion.

Stop excessive vibration
Vibration reduces the structural integrity of a battery.  Ensure battery is correctly and firmly secured.

Avoid overcharging
Overcharging produces rapid deterioration and corrosion which shortens battery life.

A battery needing to be topped up continually with water is a sure sign that the car’s electrical system requires careful checking.

Precautions
To avoid shorting, metallic objects should not be placed on top of the battery.  Batteries contain hydrogen gas and air in a volatile mixture which is easily ignited.  Keep flames or sparks away from the battery at all times.  Batteries contain sulphuric acid.  Never add acid to cells and keep acid away from eyes, skin, clothing or any other material which may become damaged.  If contamination occurs, use large amounts of water to neutralise and flush acid away.  Batteries are heavy – ensure correct lifting procedures are used when moving batteries.

Battery Care And Maintenance

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia ©2009

A Simplified Approach To Battery Charging
The rules that apply to battery charging need not be complicated.  Put simply, a battery eventually reaches a state of discharge and must be restore to peak performance.  When a charger is connected to a discharged battery, most of the charging current converts the battery’s active material back into its former fully charged state.  However, when the battery reaches about 80% of charge, charge efficiency reduces significantly.  At this point the electrolyte begins to break down into gas and as a result internal temperature increases.
When vigorous gassing begins, the charge rate should always be reduced.

Basically, there are two types of chargers designed to make battery charging safe and efficient; Constant current chargers and Constant voltage chargers.

A constant current charger maintains a relatively constant charging current throughout the recharge process.  In reality the charging reduces as state of charge increases.  However, the charger resists the tapering effect.  Most off the shelf chargers are of the constant current type.  Some have a number of charge settings to allow for fast or slow charging.  Constant voltage chargers maintain a steady charging voltage.  When connected to a flat battery the charger  works at maximum output.  As the battery state of charge increases the charge rate automatically reduces to a lower rate.

When operated at correct charging voltages, constant voltage chargers reduce the risk of accidental overcharge.  The alternator/regulator combination within a motor vehicle provides another constant “built-in” voltage charging source.  Today’s batteries are designed to offer consumers more safety, security and performance for a lot longer than ever before.  However, without proper care and maintenance a battery’s original life may be significantly reduced.

Charging a battery
Before charging begins, provide plenty of ventilation and ensure safety goggles and a face shield are worn.  Explosive mixtures of hydrogen and oxygen gases are present with the battery cells at all times.  Even a battery standing idle generates small quantities of hydrogen due to the self-discharge action.  Gas collects in the cells and can be set off by sparks, flame or a lighted cigarette.

Sparks from loose connections or metal tools making contact between the terminals or the ungrounded terminal and nearby grounded metal parts can also be hazardous.

Do not remove the vent caps and do not charge the battery unless you are thoroughly familiar with the step-by-step procedure to use.  Follow the manufacturer’s instructions on the charger.  If the instructions are no longer legible, they may be obtained from the manufacturer of the charger.  Never use a charger without instructions.

First check the electrolyte levels then, place a wet cloth over the battery top and vent caps.  Turn the charge rate switch and timer to the OFF position before connecting the leads to the battery.  Next, connect the charger leads to the battery terminals, red positive (+) lead to positive terminal and black negative (-) lead to negative terminal.  Rock the charger lead clamps to make certain a good connection has been made.  Set the electric timer to the desired charging time.

Now, turn on the charger and slowly increase the charging rate until the desired ampere value is reached.  Do not charge in the red zone.  If the battery starts to emit smoke or dense vapour, shut off the charger and reject the battery.  If violent gassing or spewing of electrolyte occurs, reduce or temporarily halt the charging.

Never touch the charger leads when the charger is ON.  This could break a connection at the battery terminal and create a spark which could ignite the explosive gases in the battery.

Never break a “live” circuit at the battery terminals for the same reason.  Always turn the charger OFF before removing a charger lead from the battery.

Battery Charging

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia ©2009

Batteries must be subjected to regular testing to ensure their starting capacity is maintained at an optimum performance level.  A battery must also be scrutinised for any physical condition which may reduce battery life and impede starting performance such as broken or damaged posts and leaks to the battery case or lid

The first step in evaluating starting capacity involves testing a battery’s state of charge using a hydrometer or voltmeter.  All non-sealed batteries should be checked using a hydrometer.  As a cheap and reliable method of determining state of charge, the hydrometer also reveals differences between cells and allows visual inspection of the electrolyte colour.  Where the hydrometer reading shows no significant difference between cells and produces a reading of 1230 or above (at 20-25C) the battery has sufficient charge for a load test.

Sealed batteries must produce a voltage of 12.5 or greater before a load test may be performed.  Since the loss/fail criteria varies depending on the make of load tester used, be sure to consult the instruction manual provided with the tester to ensure success.

Battery Testing

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia

Batteries contain highly corrosive sulphuric acid and explosive hydrogen and oxygen gases.  Batteries must be handled with extreme care at all times.

Handling battery acid
When working with acid, such as filling batteries, use a face shield.  If many batteries are handles, wear protective clothing for extra safety.

Extreme care must be taken to avoid spilling or splashing electrolyte since it can destroy clothing and burn the skin.

Care should also be taken when lifting and carrying batteries.  If excessive pressure is placed on the end walls of a plastic cased battery, it could cause electrolyte to seep through the vents.  A battery carrier should always be used, otherwise batteries may be lifted with your hands carefully placed at opposite corners.  If electrolyte is spilled or splashed it must be neutralised immediately and then rinsed with clean water.  Baking soda or household ammonia mixed with water makes an effective neutraliser.

Electrolyte splashed into the eyes is extremely dangerous.  If this should happen, force the eye open and floor it with cool, clean water for approximately 15 minutes.  A doctor should be called to the scene for immediate medical attention. 

However, if this is not possible, follow the doctor’s instructions to take emergency action.  Do not add eye drops or other medication unless advised to do so by the doctor.

Be sure batteries and acid are placed well away from a child’s reach.  If acid is taken internally drink large quantities of water or milk.  Follow with milk of magnesia, beaten egg or vegetable oil.  Call a doctor immediately.

If electrolyte is spilled or splashed on any surface of the car, it should be neutralised and rinsed with clean water.

If it becomes necessary to prepare electrolyte of a desired specific gravity, always pour the concentrated acid slowly into the water – do not pour water into the acid.  Heat is generated when acid is mixed with water.  Add small amounts of acid slowly while stirring.  Allow to cool if noticeable heat develops.  Except for lead or lead lined containers, use non-metallic receptacles and/or funnels.  Do not store acid in excessively warm locations or in direct sunlight.

Danger of exploding battery
Batteries generate explosive gases.  It only takes a small spark, flame or burning cigarette to set off a dangerous explosion.  Therefore, these and other ignition sources must be kept well away at all times.
Hydrogen and oxygen gases are produced during normal battery operation and escape through the battery vents.  Make sure working areas are well ventilated to avoid creating an explosive atmosphere around the battery.

Ensure safety precautions continue to be observed after a battery has been charged as explosive gases may still be present for several hours.

An exploding battery may cause serious injuries including eye injury from flying pieces of the case or cover.  Always wear safety goggles and a face shield when working near batteries.

Never lean over the battery during charging, testing or “jump starting” operations.

Do not break “live” circuits at the terminals of batteries because a spark invariably occurs at the point where a “live” circuit is broken.

Make certain the charger cable clamps or booster leads are clean and making good connections.  A poor connection can cause an electrical arc which could ignite the gas mixture and explode the battery.

Take care to ensure tools or other metallic objects do not fall across the terminal or any adjacent metallic part of the vehicle.

Do not smoke when working under the hood of a car or near a battery.  Never strike a match or bring any other flame near a battery.

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia

SAE Cranking Current
The Society of Automotive Engineers (SAE) defines starting power as the “SAE Cranking Current” or Cold Cranking Amps (CCA) which is the internationally recognised industry standard to determine battery starting capability.  The cold cranking test is conducted at – 18C to simulate very cold, difficult to start conditions.  The battery’s ability to perform is measured by the amount of current the battery can deliver over a short period of 30 seconds (referred to as the 30 second rate) while maintaining a voltage equivalent of 1.2 volts per cell or higher.  Therefore, a 12 volt battery must maintain a voltage equivalent of 7.2 and 3.6 for a 6 volt battery.

Reserve Capacity
A battery’s reserve capacity must sustain a minimum electrical load for ignition, headlights, windshield wipers and defroster under cold winter conditions in the event of a charging system failure.

The reserve capacity rating represents the number of minutes at 25C a battery can supply a load of 25 Amps and maintain a voltage of 1.75 volts or higher per cell.  (10.5 volts for a 12 volt battery of 5.25 volts for a 6 volt battery).

Amp Hours
No longer in popular use as a standard for rating automotive batteries, the “Amp Hour” rating represents the current a battery can supply for 20 hours.  For example, a 50 Amp hour battery supplies 2.5 Amps for 20 hours.  2.5 Amps x 20 hours = 50 Amp hours.  The standard was abandoned because it fails to rate the starting capability of a battery and its ability to power a typical accessory load.

The Amp hour rating does have benefits with regard to cycling batteries.  A battery’s efficiency varies depending on the rate of discharge.  The rating for cycling batteries uses Amp hours at three separate rates of discharge (see table).

20 hr 50 Amp Hrs (2.5 amp x 20 hrs)
  5 hr 41 Amp Hrs (8.2 amp x 5 hrs)
  2 hr 34 Amp Hrs (17 amp x 2 hrs)

Plates per Cell
In the past, it was assumed that “The more plates the greater the power”.  Therefore, “An 11 plate battery is more powerful than a 7 plate battery”.  Plates per cell has been discarded as a measure of battery performance because the size of the plates is more relevant to performance than the number of plates.  The area of plates determines starting power and the weight of active material determines reserve capacity.

A large number of thin plates that are small in surface area are likely to have less cranking power and less reserve power than a small number of thick plates that are large in area.
This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia

Although the average life of car batteries has increased to 42 months under normal operating conditions, a battery’s life can be reduced by factors involving storage, vibration, temperature conditions, overcharging and cycling.

Storage
Batteries have a limited shelf life and when stored gradually lose their power to perform.  On average, a fully-charged battery takes about 13 weeks to gradually discharge to less than its optimum operating level.  The rate of charge loss depends on battery type (low maintenance or maintenance free) and temperature conditions.
Charge loss becomes more evident when temperatures increase.  At 20C low maintenance batteries lose approximately one half of one percent of charge per day (30 percent in 60 days).  At 30C charge loss is usually double the rate for 20C.

Under similar temperature conditions, maintenance free batteries lose their charge more slowly than low maintenance batteries.  Excessive humidity will also accelerate charge loss.  Batteries stored upright in cool and dry conditions is ideal.

Whilst in storage batteries have not been recharged and allowed to go flat, may be permanently damaged.  Recharging every four to eight weeks, depending on storage conditions, will restore batteries to “as new” condition.

Vibration
Vibration loosens active material from the battery plates which may cause shorting and can also damage the structural integrity of battery connections.

Overcharging
Overcharging permanently damages batteries, therefore overcharging corrodes the grid mesh and accelerates loss of active material from the positive plate.  It also deteriorates separators and increases water loss.

High temperature
A higher temperature requires higher charge rates which leads to an accelerated loss of active material from the positive plates, as well as separator deterioration, increased grid corrosion and water loss.

Cycling
Charging and recharging causes expansion and contraction of positive active material which leads to increased shedding.  The depth and frequency of discharge influences the amount of deterioration.

Sulphation
Sulphation occurs when a battery is stored over a long period of time in a state of low charge.  The crystalline structure of the discharged active material, (lead sulphate), is gradually transformed into a substance which resists recharge, causing permanent deterioration.

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia

A battery is an efficient and compact energy storage centre created by a manufacturing process that combines chemicals, grids, plates and separators to produce electrical power.  Within each cell a battery houses a group of alternate positive and negative plates held apart by separators and bathed in electrolyte.
Since each cell supplies approximately 2.1 volts, a six volt battery would contain three cells connected in a series.  Six cells would prove a “12 volt” battery (actually 12.6 volts).  The size, thickness and number of plates in each cell determines a battery’s capacity.
Taking a look inside a typical battery you will find:

Chemicals
A lead acid battery contains four chemicals:
· Lead – Which is used to make the grids, straps, posts etc.  It is also used in a sponge form as the active material found on negative plates.
· Antimony – Only a small amount of antimony is necessary to harden the grids which would normally be soft and easy to bend.
· Lead Peroxide – Manufactured by oxidising pure lead electrochemically, lead peroxide is the active material found on positive plates.
· Sulphuric Acid – Diluted sulphuric acid forms the electrolyte acid solution which contains about 25% sulphuric acid and 75% water by volume.  This corresponds to a specific gravity of 1.260 at 25C.

Grids
The grids within a battery compose a solid framework designed to hold the active material in place.  Cast of lead and antimony, the grids also conduct the electrical current produced by the active materials to the battery terminals.

Plates
Positive plates are grids covered in a lead peroxide past and are dark brown in colour.  Negative plates are pasted with grey sponge lead.  The negative sponge lead and the positive lead peroxide create the two different metals necessary to enable a lead acid storage battery to produce electricity.

Separators
Separators prevent positive and negative plates from making contact, which results in shorting causing the battery to self discharge.  Separators are thin sheets of non-conducting porous plastic material which are inserted between the plates or completely encasing a positive or negative plate.  A rib faces the positive plates and provides greater electrolyte volume in addition to minimising the area of contact with the positive plates.  Many batteries also feature glass fibre retaining mats placed between the positive plate and the separator to slow the loss of active material from the plate.

Electrolyte
The sulphuric acid in the electrolyte is absorbed within the positive and negative plates, producing a chemical reaction which is then released as electrical power.  The electrolyte also carries the electrical current within the battery between the positive and negative plates passing through the separators.

Container
The container houses the pates, separators and electrolyte.  Usually constructed of polypropylene, it must withstand extreme heat and cold as well as shock and vibration.  Bridges at the bottom allow a space for the active material to settle during battery life without the danger of shorting.

Element Construction
The desired number of positive and negative plates are interleaved with separators to form an element or group.  Like plates are welded together at the plate lugs.  Each element connects to the one adjacent to it in a series (positive to negative).  For greater performance there is always one more negative plate than positive.
Any number or size of plate may be used in an element, depending upon how much energy needs to be stored.  Of course, increasing the size and number of plates creates a higher ampere rate during discharge at low temperatures.  (ie: a high CCA rating)

Connecting elements together
Connectors are used to connect al the elements together to form a series within each cell.  They are designed to carry a much higher current than normally required to ensure melting does not occur when starting.

Three types of connectors are used including:

“Conventional old style” connectors which connect elements together on top of the battery.
“Loop-over” connectors which use straps to loop over the cell dividers and are welded and placed under the cover.

“Through the partition” connectors which are made directly through the cell wall and are sealed by crimping under high pressure and lead welding.  This is by far the most common method used.

Covers and vent caps
Covers and vent plugs prevent electrolyte spillage and keep out dirt and other impurities.  A cover may have three or six vent holes depending on the number of cells.  Generally, heat and pressure is used to seal them to the container.  A vent cap closes the vent holes and provides a convenient way to check the electrolyte level.  Vent caps also allow gas to escape when charging the battery.  Some are fitted with a porous disc to prevent externally induced explosions.

Terminals
Terminals are the battery’s external electrical connection points and are normally located on top of the battery.  They are moulded into the cover and connect internally to the post in the two end groups.  To minimise the danger of installing a battery in reverse, the positive terminal is slightly larger than the negative terminal.

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia