Virtual Mechanic

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

Batteries produce their power through a chemical reaction which is released when a load, such as a light globe, starter motor or electric fan, is connected to the battery.  As was observed more than 100 years ago, when two different metals are placed in a liquid capable of conducting electricity, and the metals are connected together above the liquid, electrical current flows through the connection.

The different metals are referred to as electrodes.  Pure lead is used for the negative electrode or plate and a lead dioxide paste is used for the positive electrode.  When combined, they are referred to as a cell.  Two or more cells connected together are called a battery.  The liquid solution is called an electrolyte which consists of a diluted solution of sulphuric acid.  The battery becomes discharged or flat when no more current flows through the cell.  The cell can be recharged by forcing electrical current back through the cell in the reverse direction.

The chemical reaction that takes place during discharge converts both the positive electrode and the negative electrode to lead sulphate.  Water is produced and dilutes the strength of the acid.

The chemical reaction is written as follows:

During recharge the electrodes are converted back to lead dioxide and lead.  The water produced during discharge is consumed, returning the acid to its original strength.  In addition, some electrolysis of the water in the electrolyte occurs breaking it down into its component gases, hydrogen and oxygen.

The rate at which the gasses are produced is greatest when the battery reaches a fully charged state.  Also the higher the charging current, the more gas produced.

Batteries have a series of vent flues that allow the gas to escape the system.  Hydrogen gas is highly volatile and sparks or flame can easily ignite the gas and cause an explosion.  Therefore great care must be taken to adhere to established safety precautions, especially when recharging.

A battery’s electrical pressure or electromotive force is measured in volts.  The flow of electrical current is measured in amperes.  The mathematical relationship between electrical power and its components is as follows:

(Volts are represented by the symbol  ‘V’, amps  ‘I’ and power or watts  ‘P’.)
                      P      =    IV
                  Watts    =   Amps x Volts
         or      Amps    =   Watts
                                    Volts
         or      Volts     =   Watts
                                   Amps

Also, “Ohm’s Law” expresses a mathematical relationship between volts, amperes and resistance (Ohms) in an electrical circuit.

                  Ohms   =    Volts
                                   Amps
         or       Volts   =    Ohms x Amps
         or       Amps  =    Volts
                                   Ohms

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

Today’s automotive battery has undergone an evolution of change since its humble beginnings more than 180 years ago.  But some of the most significant changes have occurred in only the last ten years.

Modern cars demand more powerful batteries to cope with advances such as electronic ignition systems, on-board computers, air conditioning, mobile phones and central locking.  Compared to 30 years ago when the average car produced a typical total load of 275-300 watts, today an average car can produce a total need of 1500-2000 watts, (with all electrical accessories turned on).

This significant increase in demand prompted a dramatic shift in the method of determining battery power.  In the past, a battery’s power was determined by the number of plates per cell which proved to be misleading.  As technology changed and times became more competitive, manufacturers started reducing the size of batteries.  Although the number of plates remained constant, the area of lead, the true determinant of a battery’s power, was reduced.

As a result, Cold Cranking Amps (CCA) ratings are now the internationally recognised industry standard for accurately determining true battery starting power.  The higher the CCA rating, the more powerful the battery producing higher starting voltages to meet the demands placed upon it.

CCA ratings required for powering the average Australian car have also steadily increased from 220-250 CCA in 1960, to 375-400 CCA in 1990.  A battery purchased below the original equipment specification set by the car manufacturer is considered undersized and will result in a shorter battery life, reduced cranking power and increased starter motor power draw.

Another Significant advancement has been the appearance of the maintenance free and low maintenance type battery.  The low maintenance battery was developed using grids of plates manufactured from a combination of lead and alloys.  As a result, it only requires the addition of electrolyte only once per year.  The maintenance free battery does not require the addition of electrolyte for the normal life of the battery due to an even more refined grid construction.
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

Most people are familiar with the conventional “SLI” ) Starting, Lighting and Ignition) lead-acid battery which delivers the high amp energy necessary to provide maximum starting power.  Once the engine has started, the alternator recharges the battery.  However, repeated cycling, as well as the continual process of discharging and recharging, eventually weakens the :SLI: battery which provides concentrated starting power, the deep cycle type battery supplies a constant but relatively low amount of current for a long period of time when an extended power supply is preferred.

Battery technology covers every automotive need from original equipment for Australian manufactured vehicles to batteries designed to suit specialised requirements.

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

In addition to providing the starting power required, the automotive battery also supplies power to accessories such as lights, fans and radio when the engine is not running.  Between low engine speeds and when accessory load is greater at high running speeds, a battery makes up the difference by stabilising the alternator output.

This stabilising effect also protects a vehicle’s electrical system by smoothing out sudden high voltages which can damage electrical components.

Ask the average battery purchaser this question and most would say that a battery is simply the source of power necessary to start the engine of every motor driven vehicle.  Since most purchases are unplanned for, consumers usually have little knowledge or understanding about one of the most vital components of an automobile – the very essence of its electrical power.

With the increased demand of today’s technologically advanced cars, a basic understanding of the automotive battery, how it works and how to maintain it to ensure maximum performance and safety has become more important than ever.

The automotive storage battery falls under the category of a secondary battery.  Secondary batteries are rechargeable, unlike a primary battery which is not rechargeable and used to power devices such as flashlights and transistor radios.

This article is found in the Virtual mechanic CD Rom

Batteries what are they ?

The battery

PURPOSE
The battery is designed to store power and deliver power to all accessories.  Also to receive charge from the alternator.  Batteries are only as good as their connections and connections on the battery poles should not have any white powder or corrosion built up.  This is a problem.  The purpose of the battery is to hold current, receive charge from the alternator and deliver power to all accessories.  Batteries 20 years ago would last around 10 years.  Batteries today, on average, last somewhere between 18-24 months.  If you’re lucky the battery will last 4 or 5 years, but this is an isolated scenario.  Batteries don’t last long as they are designed differently, but still maintain a high price.

THINGS TO LOOK FOR
A battery may be no maintenance, low maintenance or maintenance.  The best one is a maintenance battery with the screw tops so that you can check the water level.  Most batteries will take normal water but if unsure of the quality of the water, then just to be on the safe side, use distilled water.  Don’t over fill or under fill a battery.  The best way to check a battery is to make sure that the water level is always over the plates.  If one cell is descending faster than the other this indicates that the battery is on the way out.  If the battery is vaporising and causing the terminals or poles to corrode with white powder, this is an indication that the battery is over working, either getting to the end of its life or being overcharged by the alternator.  A battery is designed to receive a charge rate of 13.3-14.2.  The preferred charge rate is 13.8-14.2 but that only applies to a very good charging system.  Batteries are only as good as the power they receive and the connections.  Batteries must be secure and held down by a battery clamp.  If not, then the battery may move around and cause an under bonnet fire.  When checking the battery take care not to accidentally put a spanner on the positive connection and earth as the battery may blow up in your face.

IS IT EXPENSIVE TO REPAIR?
Batteries vary, depending on the make and model..  The best battery to buy is one with a 2 year warranty.  Batteries do have a higher mortality rate than the average vehicle component.  Remember to keep your receipt and don’t expect the battery to last  any more than 3 years.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT
If fitting a battery, be very careful to make sure the terminals are in the exact location as the old battery.  These terminals vary from battery to battery according to the manufacturer and the make and model.  These terminals are situated at different locations to allow the connections to be connected with slack.  Remember, if fitting a battery and you find the positive or negative terminal very tight or just making it to the battery pole, when the engine revs, the engine will move and the battery cable will become tight and move around and the battery pole may be yanked out of the battery causing acid to pour everywhere.

Cooling/Electrical System – FanBelts
 Checking the fan belt is an easy task. By pushing on the fan belt you can ascertain if the tension is firm or loose. Also, first thing in the morning, by revving the engine, you may notice a high pitched screech. This indicates the fan belt is loose and needs attention ASAP. A high pitched screech may also self destruct a fan belt particularly if it’s a polyrib belt, that is a later generation type belt. It’s also called a serpentine belt.

Alternator
 PURPOSE
The alternator is a component that is fitted outside or around the front of the engine. It is a round component and has a fan belt connected to it. If the fan belt is connected tightly it will allow the alternator to charge somewhere between 13.8-14.2 volts. The alternator is designed to charge at this voltage to the battery. The alternator’s purpose is to keep the battery recharged..The alternator is not designed to fully charge the battery if the battery is flat. If the battery is flat have it recharged by an auto electrician and then the alternator will keep the battery recharged at its full capacity. The alternator may have an external voltage regulator or an internal regulator. Most have an internal voltage regulator which regulates the voltage. The internal voltage regulator may have brushes attached to it as a complete unit and this is the component that allows the battery to receive the charge.

THINGS TO LOOK FOR

The alternator should have a tight fan belt. If not, this will affect the charge rate. An alternator should also have a secured lead and terminal at the rear of the alternator. This is the main terminal that connects a heavy duty lead from the alternator to the battery. Alternators should be checked for the voltage across the terminals at the battery for 13.8-14.2 volts. If this isn’t the case, then check the voltage at the rear of the alternator on the positive terminal and the earth on the battery terminal. If this is a lower voltage, it is showing that the battery has got a voltage drop therefore an extra lead made up to go from the alternator to the positive battery is another way of ensuring a good charge rate to the battery.

IS IT EXPENSIVE TO REPAIR?

Depending on the make and model , the alternator can cost around $150.00-$200.00 for a reconditioned alternator. Some alternators can be purchased new. Whether purchasing a reconditioned or new alternator, be sure to get a 12 months warranty. as alternators, depending on the make and model do fail. With reconditioned alternators, it depends on the auto electrician. Find a good auto electrician, preferrably one that is recommended.

ELECTRICAL SYSTEM – Battery terminals
 PURPOSE
The purpose of the battery terminal is to hold all the cables either on the negative or positive battery poles. The battery terminal needs to be in fixed position. A sure connection is a connection that will not move. The best battery terminal is a brass battery terminal as it is not workable or malleable. There are many different types of battery terminals on the market. Most of these terminals do require replacing over 10 years and should be replaced with a brass terminal. Some battery terminals may be eaten away by the battery acid.

THINGS TO LOOK FOR

The plastic terminal may look clean and perfect but the problem is that if you need to jump start the vehicle, the connection inside the red or black terminal might be isolating the connection or causing a bad connection to the battery pole. The best way to eliminate this possibility is to cut off the red and black terminal and replace it with a brass battery terminal. This way you can see the connection and it is a sure connection. A hard to start engine or a non cranking engine may be due to a faulty battery terminal. The only way to successfully check this is by removing the terminals and cleaning both poles and terminals with a wire brush and replacing them. This might get the car started.

IS IT EXPENSIVE TO REPAIR?

A good brass battery terminal costs around $5.00. There are lead and steel terminals on the market but the best ones are the brass terminals that enable the cables to be mounted on the top. There are clones of the brass terminal that hold the cable on with thin plates. This plate has to have a thickness of 1 mm to hold the cable secure when the cables contract and expand.

TEMPORARY REPAIR AND LONG TERM REPLACEMENT

You can only really replace a battery terminal.