Regardless of what kind of car you drive, one thing that they all have in common is the 12V battery that is used as part of the starting process, as well as the power source for your car’s many electrical functions on which you have come to depend. There are a number of everyday factors that work to drain your car battery, namely:
- Leaving your headlights on without the engine running
- “Parasitic draw” – clock, radio, or other function in the car left on or running on a kind of standby or idle mode
- Loose or corroded battery connections
- Extreme outdoor temperatures (hot or cold)
- A problem stopping the battery from charging while you have the engine running
- Lots of short drives, nothing else
Finally, an old battery will also lose its capacity as all of them do over time, including the fancy new battery packs used in electric cars. Nowadays, there is more than ever drawing from that humble 12V battery under your car bonnet. Our new social distancing and lockdown regimes are also seeing our cars shut in the garage or sat on the drive for weeks at a time. How can we avoid our car batteries going flat?
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How to Avoid a Flat Car Battery
There are several key ways you can use to stop the car battery going flat. We’ll detail them below.
1. Go for a Drive
One of the biggest differences between your 12V battery and one of the fancy new electric car lithium-ion battery packs is that your regular car battery is charged by the running of your car’s engine. The mechanical whirring of your internal combustion engine is the physical action that restores the 12V battery to health. That’s why you normally don’t have to take any specific charging steps for this battery.
At times when strain on your battery is more, or when the car is sitting idle for long periods of time, the best thing to do is to take the car out for a drive. If you start the car and drive it out for 15-20 minutes, it will be enough to maintain a sufficient charge in the battery.
2. Use a Trickle Charger
If taking the car out for a drive is not an option, you can maintain the charge in the car’s battery by using a trickle charger. It connects to your mains electricity and by means of a converter trickles a slow and steady stream of power into the battery once properly connected. When connecting the battery, follow the instructions of your charger exactly as written to avoid shocks or other problems.
Trickle chargers are useful to have at home for other reasons, too. If your battery were to go dead at any point, for any reason, you could use a trickle charger on the battery for a short while to build up enough charge to get the car started. Once you can get it started, the engine can do the rest of the charging.
3. Don’t Use the Car on Very Short Journeys
When you take the car on a very short journey, you’re using power to start the engine and probably use the car’s electronics, but not running the engine for a long enough time to ensure that the battery can recharge itself. If you do this continually over a long period, then the result is the battery loses more charge than it gains and will, sooner or later, become depleted.
When the journey is short enough to walk, then walk, or use public transport. Alternatively, you could take the car on your original short journey, but find a reason to extend the journey to allow the battery more charging time on the running engine.
4. Alternate Vehicles
If your household has multiple vehicles, then you should be sure not to leave one sitting idle while you continuously use the other. Rotate and alternate between your cars to ensure that each of them can get a good number of 15-20 runs each week in order to maintain their proper charge.
Some families also have a car that they only use on special occasions. It might be a more luxury model like a Jaguar or an Audi TT that only emerges on Sundays, for example. In these times of lockdowns and tiered restrictions, that special-occasion car might have been sitting idle in your garage for much longer than usual. Ensure that you take it out, even if you’re just doing the school run or a supermarket run.
5. Check for Signs of Corrosion or Degradation
If you pop your bonnet open and take a look at the battery (without touching) you should be able to identify where the main positive and negative connector points are. Take a closer look at these and see if you can see any signs of rust, corrosion, residue build-up or something else that looks wrong. If it looks bad, then you should let an experienced mechanic cast an eye over it to make sure it’s in good health.
Many battery problems are caused by car owners not keeping an eye on the battery health, or ignoring apparent issues with the battery.
6. Unplug Devices and Switch Off Electronics
One of the most common reasons that a battery goes flat overnight is because someone left the lights on when parking up for the night. They may have also left the dome light on, or another electronic device plugged into the power outlet of the car.
To ensure no unnecessary drain on your car’s battery, ensure that you heed the car’s reminders to switch off lights and electronics, and don’t leave any devices plugged into any of the car’s power outlets.
7. Complete all Car Maintenance
Finally, a car that isn’t properly maintained will be more of a strain on the battery. For instance, if you tyre pressure is too low, it puts strain on the entire powertrain and drivetrain in your car, including the battery. Above we also mentioned the dangers of not properly checking for defects and signs of degradation in the battery casing and connectors. Keeping your car properly maintained is one of the best things you can do to ensure battery health.
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Don’t Ignore the Battery, and It Won’t Let You Down
The 12V car battery is a pretty simple piece of tried-and-tested technology. If you look after the battery, keep it charged, and stop any unnecessary strain being put upon it, you’ll find there won’t be any flat car batteries in your future.