Battery Myths

Common Battery Myths

We answer some common battery myths.

I left my lights on for a few hours and discharged (flattened) the battery. A drive for half an hour should charge it up.

FALSE. There are several factors which will always prevent a vehicles charging system from fully recharging a battery. Issues such as how much power from the alternator is diverted to the battery, how long the alternator power is available, the size and depth of discharge of a battery and the temperature all work against restoring a battery to an acceptable level of charge. It must be recognised that normal or extended driving, Idling the engine for periods of time, short stop-start trips, driving in hot or cold weather or at night will not fully recharge a battery. Surface charging or continuous undercharging will lower the capacity of the battery over time and deep discharges can damage batteries and will shorten their lives. When a discharged (flat) battery needs to be recharged, the only way to reliably restore it is to use an appropriate multi-stage battery charger. The charger voltage needs to be high enough to mix the battery acid evenly in the electrolyte to prevent ‘stratification’. You will also save wear and tear, and fuel by using a charger to restore the battery to its maximum charge.

I don't drive my car that often and sometimes go away for several weeks and now the battery is discharged (flat). Is it normal for a battery to go flat if the car is not driven?

TRUE. Batteries have a natural self discharge or internal chemical leakage. All modern vehicle electrical systems draw a tiny amount of power from the battery when not in use. This is normal to keep all the electrical systems ‘alive’. Over time the battery will become fully discharged if not driven. The only way to overcome this is to use the vehicle regularly or connect a maintenance charger, which will keep your battery in good condition.

The battery was discharged (flattened) a few months ago and I've had the car jump started a couple of times. The battery is less than twelve months old, shouldn't it be replaced under warranty?

FALSE. No amount of driving will recharge a discharged battery to a reliable level. A discharged battery is generally a good battery. By correctly recharging it using an appropriate charger will in most cases restore the battery condition and prevent further breakdowns. You should also have your charging system inspected to ensure it’s producing enough power. It’s also possible the culprit draining the battery is a boot light or accessory left on. RACQ Patrols can test your battery and electrical system. If needed RACQ sell a range of chargers at member prices. Go to RACQ Batteries for all the details.

I’ve been told a 'calcium' battery is not suitable for my older car due to the lower charge rate of my alternator.

FALSE. All major battery manufacturers are now producing calcium batteries containing a proportion of calcium in both the positive and negative plates. The benefits of these batteries is less gassing and therefore reduced water loss, resulting in a longer battery and shelf life, greater overcharge acceptance and an increase in available power. It is important to remember that not all batteries are the same. RACQ Batteries have a high tin content roughly two to three times greater than most other calcium battery manufacturers. Tin is expensive, however the high content in every RACQ Battery greatly improves its rechargeability. Coupled with world leading stamped and expanded grid technology makes every RACQ Battery perfectly suited to older and modern vehicles. If you do have a low alternator charge rate it generally indicates a problem with the charging system, this should be checked by an RACQ Approved Auto Electrician.

Should I disconnect my battery terminal if I'm going away on holidays?

NO. Disconnecting the battery will affect the cars on board computer systems that require a specific amount of power to run them. If this power supply is interrupted it can cause vehicle operation issues including engine, steering, transmission and security system problems. When you reconnect the battery it may even prevent the vehicle from being started. A fully charged battery should last several weeks without effecting the operation of the vehicle. The best way to maintain a battery on extended holidays is to use a good quality maintenance charger. These chargers can be left connected for indefinite periods, ensuring your car battery will be fully charged while you are away.

Can a discharged (flat) battery affect fuel economy?

TRUE. When a battery is discharged (flattened), the car’s alternator will try to recharge the battery as best it can. This added load on the engine will use more fuel.

I used a hydrometer to test my old car battery. Can I use this to test a maintenance free battery?

NO. Maintenance free batteries are sealed, they have a greater than normal electrolyte reservoir and recycle this within the battery. If maintained they should last longer than a low maintenance battery. The way to reliably check the battery is to use an electronic tester that is designed to read the internal conductance of the plates and cells. Patrols and RACQ battery stockists in the major areas use these and are able to test your battery at the roadside.

Do I need to service a 'maintenance free' battery?

TRUE. Regardless of the battery type, they will all require the terminals to be checked and cleaned if necessary and the alternator charge rate checked during every service. Any corrosive build up on the outside of the battery also requires cleaning, this will reduce the likelihood of the battery self discharging. Once discharged (flattened), maintenance free batteries along with all other battery types will require recharging using an appropriate multi-stage battery charger.

The water level in my battery is very low and the plates are exposed. Do I just use normal tap water to top up the cells?

FALSE. To replace lost water in batteries use distilled, deionised or demineralised water wherever possible. Using tap water can produce mineral build up that can block the pores and coat the plates of the battery. In an emergency use rain water from a clean container as it doesn’t have the impurities that coat the plates. As a last resort use good quality tap water. If the cell plates have been exposed for any length of time they can dry out and fail. It would be a good idea to recharge and test the battery. It should be noted that batteries which have run out of water and failed are not covered for free replacement under warranty.

A friend of mine says the bigger the cold cranking amps (CCA) the better the battery?

FALSE. Most vehicle manufacturers design electrical systems around a specific size battery. It is now common for manufacturers to use the vehicle computer systems to regulate the power required for normal operation. Generally the electrical system will only use a fixed amount of current from the battery based on the requirements of the starter motor and electrical system. A larger CCA battery supplies only what is required. It will not damage your vehicle, however using batteries with a higher or lower capacity can affect the performance of the battery and if physically the wrong size could potentially cause damage.

I bought a new battery for my car and replaced it myself. Now the car won't idle and the radio display says ‘code’ and doesn’t work. Was this caused by replacing the battery?

TRUE. Most modern motor vehicles require the battery power to be connected at all times. By disconnecting power from the battery or when the old battery fails, the computer which controls the idle speed can lose its memory and needs to be reset by your mechanic. If the car radio also loses power it may set the security function. For the radio to work, the security code needs to be re-entered. The code should be on a card with the car owners manual, if not you will need to contact the dealer to obtain it. Some car radios have personal code numbers set by the owner, if lost it will need to be reprogrammed. When replacing batteries in late model vehicles a ‘memory minder’ must be used to ensure power is kept to the vehicle electrics at all times. RACQ patrols use memory minders when replacing batteries.

I took my car in for a service and the mechanic said the battery needs replacing. I bought a new battery from them. The old battery is under warranty. Can I claim a refund for the battery cost?

FALSE. Depending on the terms of the warranty you should always contact the battery supplier where it was purchased from first and allow them to test the battery. If the supplier tests the battery and it has failed, they can replace it for you under warranty. If the battery is replaced without advising them, the terms of the warranty agreement may have been breached and a refund may not be given. All RACQ batteries are covered by an Australia-wide roadside guarantee 24 hours per day 7 days per week for current RACQ members. For more information on RACQ Battery warranty visit www.racq.com/batteries or phone 13 11 11.

My old battery lasted less than 18 months, is this normal for a battery?

Batteries disintegrate over time, this is due to the acid slowly decaying the components within the battery. How long a battery last depends on a number of factors including, the initial construction of the battery, the climate in which the vehicle is operated, how often the vehicle is used and if the battery and vehicle have been maintained. All RACQ Battery warranties range from 6 to 36 months.

Batteries last longer in hot climates than cold.

FALSE. Car batteries last an average of two thirds as long in hot climates as cold ones. Heat kills car batteries by encouraging water loss within a battery. It is extremely important to ensure any low maintenance battery is always topped up with electrolyte. All RACQ batteries are maintenance free batteries. They have a larger than normal electrolyte reservoir to combat water loss and makes them ideal for our hot Queensland climate.

I’ve lost the hold down bracket for the battery, I shouldn't need to clamp it down as it sits in its spot OK.

FALSE. Batteries left loose inside the engine bay can vibrate and cause the battery to fail. An unsecured battery can also fall into the moving parts of the engine and cause damage. Acid can also leak from the battery damaging the engine, components and paintwork. Unsecured batteries can also ‘short out’ on metal parts under the bonnet and cause a fire or explosion. It is important to secure all batteries using appropriate hold down brackets and clamps according to the manufacturers recommendations.

The battery terminals always get a white powdery build up. My mechanic sprayed some blue stuff over them and said they won't need cleaning anymore, is this true?

FALSE. All battery terminals regardless of the battery type will corrode over time. The reason this happens is due to electrolysis. This occurs when current is passed through the dissimilar metals used in the battery posts and terminals. Poor battery connections can prevent power from being supplied to and from the battery and lead to a vehicle breakdown. The only way to prevent this is to have the terminals cleaned at every service. When disconnecting terminals always use a ‘memory minder’ to keep the vehicles electrical system powered up to prevent drivability problems.

The battery light has come on, the battery must be faulty.

FALSE. The battery or ‘power’ light comes on when there is a problem with the vehicle charging system. In older cars this was called an alternator light. The battery light indicates the car is running on battery power alone. Continuing to drive a vehicle with the battery light on will end in a breakdown and can cause other damage to the car’s electrical system. You should get your car to an RACQ authorised repairer as soon as possible or call RACQ on 13 11 11. RACQ Car Electrics offers a competitively priced Alternator replacement service.

I replaced the battery in my car myself and connected the leads the wrong way. I've now connected them correctly and I have no power in the car at all. Shouldn't the car work now they're correctly connected?

FALSE. All modern motor vehicles have a negative to ground polarity. Polarity in electrical current terms is the flow of moving electrons in a direction either negative to positive or positive to negative. By connecting the leads incorrectly the flow of electrons will be in ‘reverse’ polarity. This can damage sensitive electrical components and destroy fuses and fusible links and potentially cause an explosion from the battery. If your car won’t start call RACQ, you may need to get the car towed to an RACQ authorised repairer.

Can I use an automotive battery to run my boat?

NO. You should always buy a battery for the application it’s being used for. A marine battery is designed to handle the conditions of a vessel operating in rough conditions over water. They also have a semi deep cycle feature, which allows them to be used to run accessories for a period of time and then be recharged. RACQ sell a range of Marine Batteries at member prices.

Is a car battery OK to run the fridge in my caravan when I go camping?

NO. Using a car battery to run a fridge will reduce the life of the battery and it will eventually fail. A car battery is designed to produce a large amount of current over a very short period of time to start a vehicle. Once started, the alternator will top up the battery power used. If you are running a fridge, the best option to use is a ‘Deep Cycle’ Battery. These batteries are designed to produce a small amount of power over a long period of time. Usually rated in Amp Hours, Deep Cycle batteries are designed to be drained and then recharged. Ideally for camping you should run two batteries, an automotive battery to start the car and a Deep Cycle battery for the accessories. RACQ sell a range of Deep Cycle Batteries at member prices.