Question : As Batteries age, do their maintenance requirements change?
Yes, typically the specific gravity gets higher and gassing increases due to some battery deterioration and/or loss of reserve capacity. An older battery normally requires more charging.
Question : Can a battery really explode?
Yes, so when working with or near a battery, or jump starting a vehicle, always:
- wear glasses or safety goggles
- shield eyes and face from battery
- keep as much distance as possible from battery
- read warning labels on battery
- do not cause any flames or sparks, do not smoke
- read your vehicle instruction manual before jump starting vehicle
If you should get acid on your skin or in your eyes, flush with water immediately and seek medical attention.
Question : Can I replace the battery in my vehicle with a different physical size?
Yes, as long as the voltage is the same (e.g. 12 volts). Before doing this however, you should make sure that the replacement battery fits in the vehicle and can be properly secured (held down) to avoid excessive vibration and no contact made with the bonnet when closing. You should also check your vehicle’s manual to make certain that you use a replacement battery with sufficient capacity.
Question : Can I store a lead acid battery indefinitely?
No, a battery will self-discharge slowly over time at the rate of about 1% of its capacity per day. Allowing a battery to become discharged will ultimately lead to severe positive grid corrosion and battery failure. This is known as sulphation. An un-used battery should be recharged on a regular basis.
Question : Do batteries need to be rotated?
Yes, stock should be rotated (first in, first out) to avoid excessive self discharge and warranty date queries.
Batteries require boosting if stored for long periods or at high temperatures.
Boost if O.C.V. 12.3 volts or less, or S.G. 1.200 or less. Check electrolyte levels then charge at 5% of capacity overnight.
Question : Do I need to add acid to my battery?
No! Add distilled water only.
When electrolyte is lost under normal use, the water evaporates while the acid remains in the battery. Adding acid will therefore alter the chemical composition of the electrolyte and cause the battery to fail more quickly.
Question : How are batteries under warranty claim tested?
- Out of warranty or tampering with date
- External damage: container and posts (guidelines issued for posts)
- Missing wet plugs
- Incorrect electrolyte levels
- Foreign substances in electrolyte
- Discoloured electrolyte
This unit was designed originally to test a battery for serviceability, that is to say, to decide whether a battery should be scrapped or could be charged and put back in the vehicle.
The tester has been improved and now has LIMITED diagnostic abilities, but adjudication may be required with S.G. readings.
An advantage with the tester is that it can test flat batteries. It works by measuring the response of the battery to attempts to discharge it and then recharge it.
- Easy to follow because colour coded
- Logical progression
- Smart tester not needed
Question : How can I determine the right power requirements for my car?
Start by consulting your vehicle’s owner’s manual. It will list the manufacturer’s recommended group size and minimum power rating. This information is also available in your retailer’s battery application guide.
You should not use a battery with a rating lower than the one your vehicle’s manufacturer recommends. A higher rated battery, on the other hand, may improve starting in older vehicles and in general provide a longer battery life.
Question : How can I test my charger to see if it is in good operating condition?
Check the ammeter gauge (where applicable) or the indicator lamp on the charger.
If the charger is working properly, the ammeter gauge should deflect to an amperage level above zero once the charger is connected to the battery and is turned on. If the battery does not respond to charging within a few hours, your charger may not be working correctly.
Question : How do I avoid battery problems?
- Ensure that the vehicle charging system is in order
- Ensure battery terminals are free of corrosion and are tightly fitted
- Ensure adequate electrolyte levels in all cells – DON’T OVERFILL. Use approved battery water only. Never add acid!!
- Ensure hold downs are snug and the battery is not loose
- Ensure correct polarity
- Avoid using Jumper Cables, unless it is absolutely necessary. Check car manufacturer’s handbook.
- Don't fit the incorrect size battery to a vehicle – don’t try to save money by fitting a smaller capacity battery – refer to the original equipment manufacturers specifications
- Don't use additives to extend battery life – they do not have any long term benefits
- Don't install additional equipment to vehicles such as spotlights, winches, two way radios, amplifiers and the like will cause excessive power drain from the battery. Ask your nearest Battery Centre for advice on upgrading the battery capacity - and make sure that the “bigger” battery will fit into the tray provided in the motor vehicle.
Question : How do I charge my battery?
All lead acid batteries contain highly corrosive sulphuric acid, generate explosive gases and have warning labels which should be observed closely. For best results charge the battery as soon as you know it is discharged. To charge your battery, follow these steps and important safety tips:
- Read the charger manufacturer’s instructions.
- Put on protective eyewear, rubber gloves, work clothes and remove all jewellery
- Place the battery in a well ventilated area
- If applicable, remove the vent caps and check the battery’s water level and, if low, add distilled water to cover the tops of the plates. Do not overfill.
- To determine if the battery needs to be charged, test it with a hydrometer to determine its specific gravity and/or with a voltmeter to determine its state of charge
- If applicable, reinstall vent caps before charging.
- While the charger is unplugged, connect the leads to the proper battery terminals. Positive to positive and negative to negative.
- Set the charger to the proper settings for your battery e.g. 6 volts vs. 12 volts, low maintenance vs sealed, standard automotive vs. deep cycle.
- Plug in and turn on the charger.
- Don’t wiggle the connections to check contact while the charger is turned on or plugged in.
- Choose the lowest amperage setting initially. Once the charger is on and the battery is charging, you may want to choose a higher amp setting to reduce charge time.
- During Charging
1. Keep the vent caps on
2. Don’t allow smoking, open flames or sparks near the battery
3. Don’t allow the battery to become hot to the touch.
- After Charging
Immediately after the battery is fully charged, turn off and unplug the charger. Continuing to charge a fully charged battery will severely damage the internal plates and shorten battery life. Disconnect the leads from the battery.
Question : How do I check my water level and add water?
Remove vent caps. Look down into each individual cell to make sure that the water is covering the lead plates and is at the proper level. Add water to any cells that are low on water. Always use distilled water to fill the battery in order to prevent chemicals from contaminating the battery. Be careful not to overfill the vent wells. The fluid should at least cover the lead plates in the battery.
Question : How do I install a new battery?
- When removing old battery, disconnect earth cable first (usually negative).
- Use correct spanners
- Clean the battery tray and hold-downs with a solution of bicarb.
- Clean the cable clamps and check the cables for damage
- Connect the new battery, beginning with the starter cable.
Question : How do I jump start my battery?
First, be sure to follow these important safety tips:
- Read your auto manual on jump starting
- Put on protective eye wear and clothing and remove all jewellery
- Don’t allow smoking, open flames or sparks near the battery
- Don’t attempt to jump start a car if petrol fumes are present around either the source vehicle (good battery) or the dead vehicle
- Check the water level in the dead vehicle’s battery and fill if needed
- Use extreme caution with jumper cables!
- Avoid connecting cables in reverse polarity
- Place the source vehicle close enough to the dead vehicle so that the jumper cables reach between the batteries without stretching
- Do not let the vehicle bumpers touch
- Turn the source vehicle off before making any jumper cable connections between the two batteries
- Clean the battery terminal surfaces of corrosion to ensure clean and quick connections
Question : How do I know when my battery is failing?
Here are some warning signals that may indicate a problem with your battery or your charging system:
- your starter motor is experiencing slow or interrupted turnover
- your battery seems to lose power quickly in cold weather
- your headlights dim at idling
- the battery/charging system warning light on your instrument panel stays on for extended periods after the engine is running
Question : How do I know when to replace my battery?
You might need to replace your battery if:
- your starter motor is experiencing slow or interrupted turnover
- your instrument panel battery light indicates battery discharge for extended periods after the engine is running
- your battery seems to lose power quickly in cold or extended starts
- your headlights dim at idle
Question : How do I maintain an automotive battery that will be unused for months?
Follow the steps above for properly storing a battery.
Simply staring your car and letting it idle does NOT sufficiently charge the battery. To fully recharge a battery with your alternator, the vehicle must be driven. Highway driving provides the best charge. However, we recommend that you use a battery charger, instead of relying on your car’s alternator to fully charge a discharged battery.
Question : How do I maintain my battery?
Modern batteries are designed to give a long and trouble free life. The length of this life however is dependent upon the original condition of the battery (i.e. standard of manufacture) and the manner in which the battery is treated in service. Follow these guidelines every six months to extend the life of your low-maintenance battery:
- Maintain water level
If your battery has removable vent caps, you should rcheck the water level and add water when it is low.
- Keep terminals clean
Visually inspect the terminals and cables at least once a year especially in hot temperatures for signs of corrosion. If dirty or corroded, clean the connections with a scraper and wire brush. This will ensure a good connection and proper starting.
- Keep case clean
Keep the top of the battery clean of heavy dirt and oil with a cloth dampened by ammonia or a 50/50 solution of baking soda and water. Then rinse with clear water and allow to thoroughly dry. A dirty battery tends to hold spilt electrolyte on the external surface, providing a conductor for electrical current which leaks to earth, discharges the battery and causes the terminal clamp and nearby metalwork to corrode. Therefore, it is essential to keep the outside surfaces of a battery free from contamination. Corrosion will cause a high resistance at connections and although corrosion between terminal posts and clamps may still allow sufficient current to pass to light lamps etc., it may not start the engine. In overcoming this problem clean connecting surfaces lightly with a fine abrasive and smear them with petroleum jelly before fitting.
- Keep battery charged
If you vehicle is not driven weekly, it may be necessary to charge your battery before use. Lack of use is hard on a battery, especially an automotive battery which is designed to be charged regularly by an alternator. Any unused battery, regardless of its chemistry, will self discharge over time and if allowed to remain discharged, will undergo severe positive grid corrosion and battery failure. The rate of discharge depends on the type of battery and the storage temperature. So its important to keep your battery charged.
- Maintain water level
Question : How do I replace my battery?
- Visually inspect the battery connections and note the location of the positive (+) and negative (-) terminals.
- Disconnect the negative (-) cable from the battery with a wrench
- Disconnect the positive (+) cable
- Remove the hold down clamp which holds the battery in place
- Lift out the battery
- Inspect the battery tray for corrosion or damage. Clean or replace the tray and attaching parts as needed
- Inspect the battery cables for damage. Clean or replace the cables as needed to ensure a good connection. For replacing battery cables, contact your local Battery Centre
- Install your new battery and secure it with the hold down. Be sure the new battery is the same voltage and group size as your original equipment battery. Check to ensure that it has at least the same reserve capacity (RC) ratings as specified by the original equipment manufacturer.
- Attach the positive (+) cable to the positive (+) terminal
- Attach the negative (-) cable to the negative (-). Be careful not to over tighten.
Question : How do I test my battery?
Open circuit Voltage (OCV) Test
An OCV test may be performed with a voltmeter.
- To determine if the battery is experiencing a problem, turn off all electrical loads and the charging source.
- For an accurate reading, allow the battery to sit with no electrical loads applied for at least one hour.
- Connect a voltmeter to the positive and negative terminals and measure the terminal post voltage with no loads or chargers connected to the battery.
- To determine the battery’s state of charge, compare the OCV reading on the voltmeter to the open circuit voltage chart.
In the dark, pull your car up to a building wall or a garage door. Turn off the engine and leave on the headlights. If they’re bright then your battery is probably fine. If the lights are dim, but get brighter when the engine is started, this tells you that the battery could be bad and requires further testing. If the lights are dim and stay dim when the engine is started, this tells you that your charging system requires further testing.
Load Test :
This test is a 15 second discharge of the battery at a ½ cold cranking amp level. A more accurate testing method than a voltmeter or a hydrometer, the load test is often required to determine whether a battery is good or bad. It is used by professional technicians.
Specific Gravity Test :
This test is performed with a hydrometer, which is the most accurate hand held tool for determining the state of charge of a lead acid battery.
- Draw electrolyte into the hydrometer a few times so that the float reaches the same temperature as the electrolyte. This will increase the accuracy of your readings.
- Hold the hydrometer vertically so that the float is free and does not touch the inner walls of the barrel.
- Hold the hydrometer so that the liquid is level in the barrel and at eye level.
- When you draw the electrolyte, make sure that the hydrometer is full.
- Check each individual battery cell. If the specific gravity varies more than .050 or “50 points” among the cells while the battery is at a 75% state of charge or above, then battery is bad and should be replaced. The cells that have a specific gravity of 50 points less than the highest cell are bad cells. A hydrometer reading of 1.265 or greater t 80°F indicates a full charge for batteries.To determine the battery’s state of charge, compare the hydrometer reading to the specific gravity chart.
- To get the most accurate hydrometer reading, you should adjust your hydrometer reading according to the temperature.
Question : How does a battery work?
A battery works by storing electrical energy from the alternator as chemical energy. This chemical energy is reconverted on demand from the electrical system.
It develops voltage from the chemical reaction produced when two dissimilar metals such as the positive and negative plates, are immersed in the electrolyte, a solution of sulphuric acid and water. In a typical starter battery the voltage is approximately 2 volts per cell, for a total of 12 volts. Electricity flows from the battery as soon as there is a circuit between the positive and negative terminals. This happens when any load that needs electricity such as the radio, immobilizer or alarm is connected to a battery.
Most people don’t realize that a lead acid battery operates in a constant process of charge and discharge. When a battery is connected to a load that needs electricity, such as the starter in your car, current flows from the battery, whereafter the battery begins to be discharged.
In the reverse process a battery becomes charged when current flows back into it, restoring the chemical difference between the plates. This happens when you are driving without any accessories and the alternator puts current back into the battery.
As a battery discharges, the lead plates become more chemically alike, the acid becomes weaker and the voltage drops. Eventually the battery is so discharged that it can no longer deliver electricity at a useful voltage.
You can recharge a discharged battery by feeding electrical current back into the battery. A full charge restores the chemical difference between the plates and leaves the battery ready to deliver its full power.
This unique process of discharge and charge in the lead acid battery means that energy can be discharged and restored over and over again. This is what’s known as the cycling ability in a battery. However, automotive starter batteries do not function effectively if constantly discharged by more than 20% of its rate of capacity.
If a battery won’t start your car you usually refer to it as “dead” even though that’s not technically correct. A battery that’s merely discharged – from leaving your headlights on or from a damaged alternator – can be recharged to its full capacity. But a battery that’s at the end of its service life can’t be recharged enough to restore it to a useful power level and must be replaced.
If the battery is only discharged you can jump start it from another fully charged battery. If the alternator or another part of the electrical system in your car is damaged, they won’t be able to recharge your battery. So if your battery keeps discharging, before you replace it, have your electrical system checked. What looks like a bad battery could be an electrical system problem. If you have a bad component in the electrical system, it will keep draining a new battery and you will be stranded again and again.
Question : How is an automotive battery made?
A 12 volt lead acid battery is made up of six cells each producing 2.13 volts that are connected in series from positive to negative. Each cell is made up of an element containing positive plates that are all connected together and negative plates, which are also all connected together. They are individually separated with thin sheets of electrically insulating, porous material “envelopes” that are used as spacers between the positive and negative plates to keep them from electrically shorting to each other. The plates within a cell alternate with a positive plate, a negative plate and so on. A plate is made up of a metal grid that serves as the supporting framework for the active porous material that is “pasted” on it or solid lead.
A lead acid battery is created by alternating lead Dioxide (PbO2) the positive plates, and sponge lead (Pb), the negative plates. Then the plates are immersed in diluted Sulphuric acid (H2SO4), the electrolyte. A typical fully charged automotive lead acid battery produces approximately 2.13 volts per cell. The chemical action between the metals and the electrolyte (battery acid) creates the electrical energy. Energy flows from the battery as soon as there is an electrical load, for example, a motor that completes a circuit between the positive and negative terminals. Electrical current flows as charged portions of acid (ions) between the battery plates and as electrons through the external circuit. The action of the lead acid storage battery is determined by chemicals used, state of charge, temperature, porosity, diffusion and load. A cycle is one discharge and one recharge of the battery.
When the active material in the plates can no longer sustain a discharge current, the battery “dies”. Normally a battery “ages” as the active positive plate material sheds (or flakes off) due to the normal expansion and contraction that occurs during the discharge and charge cycles. This causes loss of plate capacity and a sediment called sludge or “mud” that builds up in the bottom of the case and can short the plates of a cell out In hot climates additional major causes of failure are positive grid growth, positive grid metal corrosion in the electrolyte, negative grid shrinkage, buckling of plates, or loss of water. Deep discharges, heat, vibration and overcharging accelerate the “ageing” process.
Batteries are made of five basic components:
- A resilient plastic container.
- Positive and negative internal plates made of lead
- Plate separators made of porous synthetic material
- Electrolyte, a dilute solution of sulphuric acid and water better known as battery acid.
- Lead terminals, the connection point between the battery and whatever it powers.
The manufacturing process begins with the production of a plastic container and cover. Most automotive battery containers and their covers are made of polypropylene. For a typical 12 volt car battery, the case is divided into six sections, or cells, shaped somewhat like one row in an ice cube tray. The cover will be dropped on and heatsealed when the battery is finished.
The process continues with the making of grids or plates from lead or an alloy of lead and other metals. A battery must have positive and negative plates to conduct a charge.
Next a paste mixture of lead oxide – which is powdered lead and other materials – sulphuric acid and water is applied to the grids.
Inside the battery the pasted positive and negative plates must be separated to prevent short circuits. Separators, in the form of an envelope, are thin sheets of porous insulating material used as spacers between the positive and negative plates. Fine pores in the separators allow current to flow between the plates while preventing short circuits.
In the next step a positive plate is placed in the envelope separator and paired with a negative plate. This unit is called an element made up of several sets of positive and negative plates, depending on the capacity in Ah required there is one element per battery cell, or compartment in the container. Elements are dropped into the cells in the battery case. The cells are connected by spot welding. The lead terminals or posts are welded on and the cover is attached by means of heat sealing. The battery is then filled with electrolyte (a mixture of sulphuric acid and water)The battery is checked for leaks.
The final check is charging or finishing. During this step the battery terminals are connected to a source of electricity and the battery is charged for several hours. When the battery is fully charged it moves to another line where the case is cleaned if necessary and the labels are attached.
Question : How long can I leave my battery unused?
Lack of use if one of the greatest enemies of a battery, especially an automotive battery which is designed to be charged regularly by an alternator.
Any unused battery, regardless of its chemistry, will self discharge over time and if allowed to remain discharged, will undergo severe positive grid corrosion and premature battery failure.
The rate of discharge depends on the type of battery and the storage temperature.
Question : How long should I charge my battery and at what current?
Generally we recommend that you use a low amp charge, i.e. as low as the battery will accept, over a longer period of time. A 10-20 amp charger can charge most automotive batteries. Fully charging a completely discharged automotive battery, for example, with a 10 amp charger may take approximately 6-10 hours at a temperature of 20°C. Lower ambient temperatures require a longer charge time.
Some chargers automatically adjust the current and length of charge according to the battery’s state of charge and then shut off when the battery is fully charged. If the charger requires manual adjustment for current shut off, check the charger’s instructions to determine the proper current and length of charge based on your battery’s rating.
Question : How often should I check my water level?
If the charging system of your car is not overcharging the battery and your car is not driven in hot places, then you may not need to add water for about 100 000 kilometres. However regularly checking the water level of your battery is a great way to extend its life. We recommend checking it every six months in hot climates and once a year in mild climates. An easy way to stay on top of this is to have your mechanic check it whenever you get your oil changed. Also if you plan to charge your battery with a charger, we recommend checking the water level before you charge it.
Question : How should the level of electrolyte be maintained?
Water only is lost from a battery during normal service therefore topping up should be carried out using approved battery water.
The use of water other than approved battery water may lead to contamination of electrolyte. This contamination would be cumulative resulting in permanent damage to the battery.
Electrolyte should be maintained at 10 mm above plates unless otherwise specified on the battery.
Acid should not be added to a battery unless some acid has been spilt or lost. Should it be necessary to add acid ensure that the specific gravity matches each cell to which it is added.
NOTE: Excessive topping up could indicate a leaking container or overcharging. Adjustments of the voltage regulator may be necessary
Question : Isn’t a sealed no maintenance battery better?
Actually a low maintenance battery with removable vent caps has advantages over a sealed no maintenance battery. Access to the cells allows you or your mechanic to:
- Extend the life of your battery when water evaporation has occurred and delay the purchase of a new one. If a sealed no maintenance battery has water evaporation or if it is affected by a charging system problem, nothing can be done to extend the life of the battery; it must be replaced.
- Perform a specific gravity test on each cell with a hydrometer which may reveal important information about the state of the battery including if one or more of the cells is defective. This test may not be performed on a sealed battery.
Question : My new car has electrical devices that operate when the key is turned off. Will that hurt the battery?
Key-off electrical loads are common. The vehicle’s electrical system is modified to accommodate this extra drain. Even so if you have a car with items that require power even after the key has been turned off, then you must be careful about extended periods of vehicle non use or driving patterns that involve frequent short trips which do not allow the battery to recharge after the drain of the initial starting.
If you do use your vehicle for only short trips and its electrical system is in good working order, you should periodically recharge your battery.
Disconnect from the car's electrical system whilst applying external charger.
Question : Should I add acid to extend my battery life?
We recommend adding nothing but distilled water. No additives have been proven to extend battery life and may actually decrease it.
Question : Should I take my car to a battery dealer?
Yes - in spite of M-F status, take car to accredited battery dealer every 12 months or 50 000 km. In addition to checking electrolyte levels, the dealer will also check the charging system, the cables and clamps. These checks will lessen the likelihood of overcharging, undercharging and explosions.
If tests show that the battery is undercharged, it should ideally be charged at the dealer. He will probably use a constant voltage charger and this should charge the battery up to about 15.0 V. These chargers are safe and need no supervision. If constant current chargers are used and the battery is very flat, it may be charged at rates up to 40% of capacity until the battery begins to gas. From that point onwards, the charge rate should not exceed 5% of capacity in order to prevent damage to the battery. Gassing begins at about 14.3 V.
When the battery has been charged, the SG’s should be checked to see that they are in the correct range and do not show a variance of more than 0.030.
The S.O.C. of the battery can be determined with a hydrometer because S.G. changes ion direct proportion to the changes in S.O.C..
At S.G’s less than 1.250 the battery is beginning to undercharge
At S.G’s less than 1.190 the battery is beginning to sulphate
Question : What are the causes of battery failure?
- Heat is the biggest enemy. Degenerative processes are speeded up, e.g. water loss and overcharge. Battery life is affected and it is a fact that batteries do not last as long in hot climates.
- Problems begin with poor battery selection, especially in aftermarket; if care is not taken in installation, undertightening may result in damage due to vibration, overtightening can damage the container and cause leakage, loose cable clamps can cause pitting of the posts, undercharging.
- Overcharging and undercharging will occur if the alternator is not working correctly. Undercharging leads to eventual sulphation which cannot be rectified in the car. In addition to persistent undercharging, sulphation is also the result of high S.G.’s (>1,320) and standing of vehicle for long periods without use, especially at high temperatures (e.g. in car parks).
- Note that batteries do not just suddenly go flat if the car manufacturer has fitted a big enough battery and a big enough alternator, unless something has gone wrong with the electrical system.
Question : What are the components in a cell?
- The basic component in the lead-acid cell is the lead grid.
- The grid supports the active material and is then known as a plate.
- Plates of the same polarity, eg, the positive plates, are joined to a lead bar, called the group bar (also referred to as the top bar or strap.
- The assembly of positive plates and group bar is known as the positive group.
- Negative plates, in the same way, make up the negative group.
- The group bar is connected to the intercell weld via a link.
- In the positive end cell, the positive group bar is attached to a post. (The part of this post that protrudes above the cover is the positive terminal post).
- In the negative end-cell, the negative group bar is attached, via a post, to the negative terminal post.
- The positive group, negative group and separator, all taken together, form an element.
- Separators provide mechanical and electrical insulation between positive and negative plates.
- Electrolyte is the name given to sulphuric acid once it is in the cell.
Question : What are the most common causes for battery failure?
Positive grid corrosion. This is a natural occurrence over time, however it is accelerated by operating in an extremely hot climate or by overcharging. Overcharging can occur due to malfunction on the part of your vehicle’s electrical system.
- Positive grid corrosion. This is a natural occurrence over time, however it is accelerated by operating in an extremely hot climate or by overcharging. Overcharging can occur due to malfunction on the part of your vehicle’s electrical system.
- Loss of electrolyte due to heat or overcharging.
- Sulphation in storage.
- Undercharging with voltages less than 13.8 volts.
- Old age.
- Using tap water.
- Physical damage due to vibration.
Question : What are the voltage regulation settings in automotive application?
Acceptable charging voltages for car regulator setting are between 13.60 volts and 14.40 votls. Voltages below this level could result in the battery not receiving adequate charge whilst votlages in excess of 14.40 volts will cause reduction in life due to overcharge and will also produce excessive loss of water. In some vehicles very high charging votlages could result in damage to electronic componenets.
Question : What does an automotive battery do?
The main function of a traditional automotive battery is to supply a burst of power to the starter when you turn the key to start the car. Beyond that primary function a battery must also have enough power to keep your car running for a short period of time (such as long enough to get you home or to the service station) should your alternator fail.
It supplies power when the alternator cannot cope with the electrical demand from the car.
It also supplies power to the electrical system when the engine is switched off. Demands made on the battery when the engine is switched off are called parasitic loads. They include anti-theft devices (satellite tracking, immobilisers) and computers.
The battery acts as a voltage stabiliser and protects voltage-sensitive loads from pulses of up to 350 volts. Typical voltage-sensitive loads are light bulbs and electronic circuits.
High voltage pulses originate in the ignition system, loose connections and the switching off of inductive loads such as window winding motors. Ripple from the alternator is also smoothed.
As vehicles become more sophisticated, the battery is called upon to deliver more and more power to items such as cellular phones, on-board computers and other gadgets that continue to draw power even after the key has been turned off. These “key-off” drains mean cars are using more powerful batteries - sometimes even more than one.
Question : What effect does extreme heat have on a battery?
Extreme heat causes the water in the battery to evaporate faster than under normal temperatures. The heat also causes the grids that make up the positive plates to corrode more rapidly. These two factors are detrimental to the long term life of the battery.
Question : What happens if overcharging occurs?
Overcharging is charging beyond the time necessary to fully charge the battery or conducted at an excessive rate in amps for the particular battery. It produces erosion and corrosion of the positive material and causes the grids to fracture reducing their ability to carry the starting current.
Overcharging is usually accompanied by heavy gassing which will accelerate the shedding of the active material from the positive plates. Excessive deposition of active material in the bottom of the battery container will cause a build up of silt which may bridge the plates and cause internal short circuits.
Overcharging is usually accompanied by high electrolyte temperatures resulting in rapid deterioration of the plates and separators.
Overcharging may cause buckling of the plates leading to perforation of the separators and internal short circuits.
Question : What is 'permanent' sulphation caused by and how can it be remedied?
Permanent sulphation is caused by:
Operating a battery in a low state of charge for lengthy periods.
Allowing a battery to stand in a discharged state for a long period.
Insufficient charging will cause permanent sulphation because the temporary sulphate is not completely removed from the plates during recharging allowing the remainder to convert to permanent sulphate.
Leaving a charged battery for long periods without regular recharges.
A battery left idle in a discharged state for a lengthy period encourages the formation of permanent sulphate and accompanying damage to the plates. If a battery is to be taken out of service and left idle, the electrolyte must be maintained at the correct level and it should be fully charged at a low rate once a month.
A possible Remedy:
A sulphated battery may recover by charging at 1 amp for seven days or until specific gravities of the electrolyte have reached maximum and constant values. This state, then indicates the limit of recovery.
Note: No benefit will be derived from the use of additives of dopes which neither prevent nor cure sulphation.
Question : What is Nominal Capacity ?
The nominal capacity (Cn) is the current in amperes which a 12 volt battery can supply for a period of 20 hours while maintaining a voltage of greater than 10.5.
NOMINAL RESERVE CAPACITY (Cr,n)
The nominal reserve capacity (Cr,n) is the period of time (in minutes) for which a 12 volt battery can supply a 25 ampere current while maintaining a voltage of greater than 10.5.
CRANKING PERFORMANCE (Is)
The cranking performance (Is) is defined as the current in amperes which a 12 volt battery at a temperature of -18°C can supply for 60 seconds while maintaining a voltage of greater than 8.4.
Question : What is sulphation?
In the normal operation of a battery the plates are converted to lead sulphate each time it is discharged. The sulphate takes the form of fine crystals which are easily and completely dissipated on recharging. However, should the plates be allowed to remain in the sulphated condition for a long period, the “temporary sulphate” may be converted to “permanent sulphate” and become impossible to remove.
The formation of permanent sulphate is accompanied by the growth of large crystals leading to uneven expansion of the plates and eventual buckling. Short circuits may result if the buckling causes wear and penetration of the separators.
Question : What is the proper way to store my battery?
Before storing your battery, you should:
- Clean the battery case and terminals with bicarbonate of soda and water.
- Check the water level and add water if needed.
- Test your battery with a hydrometer and/or a voltmeter to ensure the battery is fully charged.
- If needed, charge your battery. Batteries stored in a discharged state are susceptible to freezing, sulphation and an increased rate of discharge.
Question : What safety precautions do I have to take while handling a battery?
- Acid causes burns and corrodes metal
- Main concern is for eyes. Wear safety glasses. Flush the eyes with running or large volumes of water, wash or hose off splashes with water, then see a doctor. Washing soda and water may be used to neutralise electrolyte in inaccessible or dead end space on the vehicle.
- Wear protective clothing if working for long with acid
- Acid spills should be neutralised with bicarb of soda then rinsed with water.
- Never add water to acid when diluting acid.
- Effluent treatment facilities may be needed.
- Always read safety instructions.
- Batteries explode when they are overcharged.
- When being charged, or even when on standby, batteries may contain hydrogen gas and air in an explosive mixture. This gas may be ignited by a naked light such as matches, cigarette lighters, sparks from short circuits caused by spanners or incorrectly connecting jumper leads.
- Batteries are fitted with flash arrestors which prevent flame front from entering battery.
- Keep sources of ignition away from battery. These are flames (matches, welding torches) and sparks (poor connections, loose connections, tracking
- Take special care when jump-starting
- Disconnect the earth lead first and replace it last when removing or replacing batteries. This will minimise the risk of a short circuit between tools and vehicle frame.
- Always switch off all vehicle electrical equipment or charging equipment, when in use, before removing the vehicle of charger leads. This will minimise the possibility of sparks.
- When charging batteries ensure there is sufficient ventilation.
Question : What safety procedures should be followed when replacing my battery?
First be sure to follow these important safety tips:
- Read your auto manual on replacing your battery
- Put on protective eye wear, rubber gloves and work clothes and remove all jewellery
- Put the car in park (automatic) and in gear (standard shift) and engage the emergency brake
- Don’t allow smoking, open flames or sparks near the battery
- Avoid connecting positive and negative battery cables in reverse polarity
- Never strike a battery terminal or cable end with a hammer or wrench to loosen the connection. This may loosen the terminal and destroy the battery
Question : What should the specific gravity of a battery be?
A fully charged battery’s electrolyte should have a specific gravity of 1.280 to 1.330. A battery should be charged at a controlled rate to eliminate heat. No amount of OVERCHARGING can increase battery capacity. A battery should be discharged at a rate of current that does not increase temperature over 20 degrees.
Question : What sort of maintenance should I perform on my battery?
Modern automotive and light truck batteries need little attention. Check the battery once a year for signs of corrosion at the terminals. Clean the terminals with a mixture of baking soda and water. Keep the top of the battery clean of heavy dirt and oil to prevent low grade short circuiting.
Some batteries are equipped with removable vents so that the electrolyte levels in each cell can be checked and filled with water if the level is low. Always use good quality drinking water or distilled water to prevent iron or other chemicals from contaminating the electrolyte. Be careful not to overfill the cells or acid may be expelled during operation or charging.
If your vehicle has not been started in more than a month, recharge the battery before using the car.
Question : Which is worse for a battery, hot weather or cold weather?
While most of us have grown up thinking that cold weather is the worst weather for a battery, the fact is that your car is simply harder to start on very cold days. This is primarily due to the thickening of the motor oil during extreme cold. Heat actually damages the battery. Studies indicate that the average battery lasts nearly twice as long in a cold weather climate vs. a hot weather climate.
Question : Why did my battery fail early?
Batteries fail prematurely because of a variety of situations, including poor battery maintenance, hot weather, hot engine temperatures and a failing alternator.
Sometimes a defect in the battery may cause it to fail early, and that’s why Battery Centre offers a warranty.
Question : Why did my second battery fail in less than a month?
The possibility of getting two defective batteries in a row is remote. If the battery is undamaged and it recharges and performs well on a load test, then something else is wrong. Make sure that:
- The battery matches the vehicle’s make, model and year according to your vehicle owner’s manual or your dealer’s application guide.
- The vehicle does not have electrical modifications such as a non factory air conditioner, a large stereo system or extra running lights that may call for an upgraded battery.
- The battery hold down is secure.
- There is no evidence of shorting or damage to the terminals or cables.
- The battery terminals and cable connections are clean and free of corrosion.
- The vehicle’s electrical system is operating correctly.
Question : Why does my battery get corrosion build up on the terminals?
Although all batteries contain highly corrosive sulphuric acid, corrosion should not occur under normal conditions without spillage or one of the following:
Add distilled water to the electrolyte of a fully charged battery. If the battery requires charging, only add water if the electrolyte is at or below the plates.
Overcharging by the alternator or normal charging at an extreme battery temperature can result in excessive gassing of the battery, which may produce increased corrosion.
Inadequate metal contact:
When current passes through poor or loose electrical connections, a form of corrosion may form.
Question : Why does my battery keep failing even though I seldom drive the car?
Batteries will self discharge while unused. Also most vehicles will have some key off electrical drain from the computer memories, which may discharge the battery below a no start condition within a few days to two weeks. Connect a small charger to the battery occasionally.
If this problem continues to occur have the vehicle tested by Battery Centre for excessive key off electrical drain.
Question : Why does my battery light comes on when I’m driving?
This would typically indicate a charging system or cable connection problem.
Take your vehicle to a local Battery Centre to have the charging system, cables, connections and battery tested. This will help determine what type of problem you are having.
Question : Why does my battery start the car sometimes but not at other times?
This is probably not a battery problem.
If the problem occurs only after the vehicle sits overnight or for a day or more before starting, the problem is often a low state of charge. If the battery starts the vehicle once the vehicle has been started recently, test your battery to determine its state of charge. Also make sure that the alternator is adequately charging and that all the connections are good.
If problem continues, see your local Battery Centre.
Question : Why is the electrolyte level important?
The electrolyte level in the battery is very important.
If too high, expansion due to increases in temperature and the collection of gas bubbles on the plates during charging may cause overflowing.
Spilt electrolyte provides a conduction path to earth and may allow the battery to discharge resulting in a flat battery.
Spilt electrolyte may be removed with large quantities of water or by the use of a weak alkaline solution such as washing soda. (Dissolve 100g in 1 litre of water).
If the electrolyte level is too low the plates are exposed to the air and permanent damage and loss of capacity may result.
Vent caps should remain in position during charging to minimise the spray of electrolyte caused by gassing.
Question : Why won’t my battery take or hold a charge?
A battery may not accept a charge for several reasons. Your battery may have a bad cell or an internal short and therefore be irreparable. Or it could be so severely discharged that it will require a professional calibre charger to charge it. Many home chargers have minimum voltages that must be present in the battery before the charger will switch on. Normally these low voltages are well below those exhibited by a battery that appears to be “dead”.
Often however the battery is not given the adequate amount of time to accept a charge. One of the best tips regarding battery charging is to observe the charger’s ammeter swing needle (available on some chargers) during the charging procedure. After the charger is connected to the battery and is on, the needle should deflect to a high amperage level if the battery is partially discharged. If the battery is severely discharged, the needle only deflects slightly away from zero. Continue to observe the needle in either situation. On a normally discharged battery only, the needle will start to taper in amperage back toward zero, usually in less than five minutes. This reduction in amperage typically indicates the battery is accepting a charge. On a severely discharged battery, the needle will start off very low then rise. This rise of the needle is a preliminary indication that the battery is accepting a charge.
Always determine the battery’s state of charge before and after recharge. The most accurate method (on a removable vent cap battery) is to perform a specific gravity test with a hydrometer. If the battery will not hold a charge adequately contact the nearest Battery Centre.
Question : Will storing a battery on concrete drain the charge?
No, regarding today’s batteries, this is a myth.
A battery placed on concrete will not discharge any faster, but a battery will discharge over a period of time wherever it is placed.
If the battery has a surface layer of acid or grime which is conductive, the battery will self discharge more rapidly than if it were clean and dry.
Frequently Asked Questions