Changes and advances in vehicle technologies means the way your battery connects with your car has also changed. Here are some myths and facts about batteries in modern cars.
As the on-board computer systems in modern vehicles have increased in complexity, restarting your car when the battery goes flat has become a little less straight forward than it once was.
A jump start is not always the most hassle-free way to get back on the road. When done incorrectly restarting a car with a flat battery can result in the loss of codes, memory settings and even damage to expensive computer units.
If you’ve got a flat battery, it’s best to call in an expert.
Simply driving your car for any period of time will not fully recharge the battery, nor will just sitting idle with the engine running. Doing this when the battery is weak may even lower the battery capacity and shorten its life.
A suitable battery charger may be an option though you should be cautious about using a charger unless you know exactly what you’re doing.
Possibly. One sign may be that you hear the starter turning the engine more slowly than usual on starting the car. This is a sign the battery may be struggling. The battery light on the dashboard may light up, although this is not always an indication the battery is going to die. Be aware of battery leaks and any scaly build-up on the terminals. An older battery (more than three years) is less likely to stand extreme weather conditions. Very hot or cold weather may cause it to fail sooner. And when it does fail it’s also possible that it’s not preceded by any noticeable warning signs at all.
It’s actually the other way around: car batteries last longer in cold climates because hot climates cause water loss. Keep an eye on your battery’s water levels, especially over the hot summer months.
Yes it can. Your car’s alternator will work harder to try to recover your battery when it goes flat. This adds extra load to your engine and uses more fuel. Keep your battery charged and replace it with a new one at the first signs of it failing.
There are no guarantees as to how long your car battery will last. Its longevity may be impacted by how fresh the battery stock was when it was first installed, if it was installed correctly, how often the car is used, and whether the battery and car have been well maintained.
We do not recommend disconnecting the battery in modern vehicles. Depending on the make, model and age of your vehicle, disconnecting the battery may result in the loss of some of your vehicle’s computer settings.
If you’re going to be away for more than two weeks, ensure the battery is fully charged before you go and, if it has removable caps, check that the electrolyte level is correct. Using a battery charger is also a good idea if you have a reliable friend or family member that can switch it on/off for you whilst you're away. If in doubt, contact an automotive workshop for advice. RAC members can also contact our Motoring Advice team on 13 17 03.
If you have a maintenance-free battery you won’t need to top it up with water. In batteries where you can top it up if needed, you should use distilled, deionised or demineralised water. Tap water can produce mineral build up that blocks the pores and coats the plates of the battery.
It’s unwise to let the water level drop to leave the cell plates exposed as they can dry out and lead to battery failure. Battery warranties won’t cover a serviceable battery that has failed due to water loss.
An illuminated battery light could be caused by a number of faults, including a failing alternator or battery, poor battery connections or a problem with the alternator drive belt. If the battery connections are clean and secure and the battery light is till lit, we’d recommend having a trained technician check it out.
This is possible. Most cars need to have power all the time. Disconnecting your battery can reset the security systems and security codes in your car.
Your security code is probably on a card somewhere with your car’s manual. If you can’t find it, you might need to contact your car dealer or have it reprogrammed. All of our Roadside Patrols carry the necessary tools and information to help you get back on the road quickly which will help you avoid this problem.
This is not true. Your car is designed to use a certain size battery to match your starter motor and electrical system. Using a larger or smaller CCA battery than needed can lower the lifespan of your battery. Use the right size battery for your car and if you’re not sure ask us before you buy a new one.
All batteries have a limited life. The life of your battery will depend on the weather extremes, where you drive, how often you drive and how well you look after your battery and your car.
Keep your car in good condition with regular servicing.
This is not true. Calcium in the positive and negative plates makes the battery more resilient and allows it to have a higher output. The calcium raises internal resistance and is suited to higher charge rates.
Calcium batteries have a higher output and can be used in all vehicles. Use a suitable charger to maintain the battery if it’s flat or not used often.
All batteries need to be checked regularly and looked after. Have your battery terminals checked and cleaned to get rid of any corrosive build-up and check that your battery is secure within your vehicle. At your next service, get your alternator charge rate checked to ensure it’s delivering enough charge to your battery.
If your battery is left loose, engine vibrations can cause it to lose power. It could also leak and damage your engine, parts or paintwork. In some cases, a loose battery could even short out and cause a fire or explosion in your engine.
Make sure your battery is properly secured with hold-down brackets and clamps as outlined in your manufacturer’s guidelines.
All battery terminals need to be cleaned to keep the connections strong and slow down the process of corrosion that happens naturally over time. The best time to do this is at your next service to ensure any electrical systems are not damaged when the terminals are disconnected.
Your old battery would need to be tested at the supplier you bought it from before you buy another one. The outcome and terms of your warranty will determine whether a claim is possible.
If your car battery stops working and is still under warranty, contact your battery supplier first. They’ll test the battery for you and if it’s faulty they’ll replace it for you according to your warranty.
No, you will need a marine battery to power your boat. They’re specially designed to be used in rough conditions and in water.
No, a car battery is designed to produce a large current in a very short time to get your car started before your alternator takes over. Using a car battery to run a fridge will ruin the battery.
Get a deep cycle battery . These are designed to produce a small amount of power over a long period of time.