Spare a thought for the modern car’s battery. It leads a tough, thankless life, with multiple parasitic draws leeching at its charge even when the car’s parked and locked. From cameras to alarm systems, onboard telematics to stealthy tracking devices, it is quite literally having the life sucked out of it.

Keyless entry systems are working away. Sensors can detect a parking-bump and switch on the parking cameras. And when you unlock a relatively modern car, things get even more demanding. The door lock actuators whir into action, headlights guide you to the car, puddle lights make you feel welcome, the interior is bathed in a warm glow, the fuel pump is primed and instruments come to life. If it’s a coupé with frameless windows, they'll drop a little when you pull the door handle, while opening and closing the boot is doubtless done by electric motors.

Tony Zeal, Technical Training Manager for CTEK, the Swedish manufacturer of intelligent chargers for batteries, says today’s car battery faces all manner of demands. “Even something like a Ford F150 pickup has 150 million lines of code to operate – that’s more than Facebook, the Boeing Dreamliner, the F-35 fighter jet and the Large Hadron Collider combined.” The moment you unlock a car, all manner of control modules – computers, effectively – spring to life priming different mechanical and convenience functions all before the engine is running and the alternator can take care of the battery. Even the battery has its own control module – known as the battery energy management system.

Mix that demand together with cold weather and our driving habits and it is little wonder that the most common cause for a breakdown call out is a flat battery. Those driving habits may come as a surprise to petrolheads like us who love getting behind the wheel and putting in some meaningful miles. In the UK, says CTEK’s Zeal, the average distance driven is a mere seven and a half miles. And for 96 per cent of their time, cars aren’t being driven. That sort of use means a battery can lose nearly half of its energy capacity in just a couple of years. If you’ve ever grumbled about batteries not lasting as long as they used to, now you know the likely cause behind it.

And on a modern car with stop-start systems, a flat battery can be bad news for your wallet in more ways than meet the eye. It isn’t just that the battery will need to be replaced; it is that it will most likely have to be done by a franchised dealership which can reprogram the battery energy management system. If the new battery isn’t registered, error messages from the on-board computer may occur and comfort and convenience feature may not work or may only work to a limited extent for a short period of time. So don’t let it go flat in the first place.

The way to avoid this, says Zeal, is simple: use a battery charger. At Racing Green Car Storage, our client’s cars are fitted with smart chargers, made by CTEK. The company’s drivecycle discharge testing, designed to replicate the typical usage pattern of today’s drivers, has shown that using a smart charger can extend the operating life of a car battery by up to three times.

Let’s take a deeper dive into your car’s battery, and why a smart charger might just be the smartest purchase you’ll make for your car.

What does a car battery do?

Put simply, a car battery provides the necessary electrical energy to start your vehicle. It supplies power to the starter motor, ignition system, and other electrical components. Once the engine is running, the alternator takes over, recharging the battery and keeping the car’s electronics operational.

According to Tony Zeal,"Many people don’t realise just how much work their battery does beyond just starting the car. The growing number of electronic components in vehicles today puts increasing strain on them."

Types of car batteries

Car batteries have evolved significantly, with several 12-volt types now available:

• Lead Acid: The most common and affordable type, using a liquid electrolyte. Requires regular maintenance.

• AGM (Absorbed Glass Mat): A more advanced type, offering better performance, longer life, and superior resistance to vibration. These are commonly found in modern cars with start-stop systems.

"If you drive a vehicle with a start-stop system, an AGM battery is a must," explains Zeal. "Traditional lead-acid batteries simply can't cope with the repeated starting cycles."

‍The growing demand on car batteries

‍As vehicles integrate more electronic systems – automatic braking, adaptive cruise control, heated seats, and entertainment systems – the demand on batteries has never been higher. Start-stop systems also increase battery wear by requiring repeated engine restarts, which is why many modern vehicles use AGM batteries to handle the load more effectively. Zeal adds, "With all the extra tech in cars today, we’re seeing batteries wear out much faster than they did 10 or 15 years ago. It’s no longer just about cranking the engine; it’s about managing a whole network of complex electronics."

‍How does a car battery recharge?

‍Once the engine is running, the alternator generates electricity to power the vehicle and recharge the battery. However, short journeys may not provide sufficient time for a full recharge, leading to a gradual depletion over time. The shaft of the alternator is connected to the engine via a belt and pulley. When the engine is running, the shaft of the alternator is forced to rotate. This rotation generates electricity. Watch this film to findout more detail.

‍Why do batteries go flat?

‍A flat battery is one of the most common reasons for a car failing to start. The primary causes include:

• Lack of driving: If a vehicle is left unused for extended periods, background systems slowly drain the battery.
• Cold weather: Low temperatures reduce battery efficiency and cranking power, making it harder for the engine to turn over, especially when the battery is old and has lost some of its capacity to hold energy.

"Cold weather is a battery’s worst enemy," says Zeal. "A battery that was working fine in summer might suddenly struggle when temperatures drop."

‍The consequences of a flat battery

‍Allowing a battery to fully discharge can shorten its lifespan significantly. A deeply discharged battery can develop sulphation – a build-up of lead sulphate crystals – which reduces its ability to hold a charge. "The problem with letting a battery go completely flat is that even if you get it started again, you may have already caused irreversible damage," warns Zeal.

‍Battery maintenance: Prevention is better than cure

‍Regular checks can prolong battery life and prevent unexpected failures:

• Water levels (for lead-acid batteries): Ensure plates are completely covered in electrolyte.
• Terminals: Check for corrosion and clean if necessary.
• Voltage tests: A healthy battery should read around 12.6V when fully charged.

‍Checks when replacing a battery

• Manufacturing date: Typically, a car battery lasts 3-5 years. Check the date code to determine its age.
• Power requirements: Ensure the replacement battery meets your vehicle’s cranking amps (CA) and cold cranking amps (CCA) needs.
• Correct fitment: Ensure the new battery’s dimensions and terminal polarity match your car’s specifications.

Battery isolator or smart charger?

‍For vehicles that aren’t driven regularly, a battery isolator can prevent drain by disconnecting it from the electrical system. Alternatively, a trickle charger keeps the battery topped up, preventing discharge over time, and for modern cars that tends to be the preferred approach as it helps avoid complex electronics throwing up errors that will require further instigation by a garage. "If you don’t drive often, investing in a trickle charger is a no-brainer," says Zeal."It keeps your battery topped up and ready to go, even if your car sits idle for weeks."While highly effective, smart chargers have limits. They can only charge batteries within a specific size range and maintain a limited capacity.

‍CTEK: The smart-charger revolution

‍Before the advent of smart chargers, battery maintenance was a cumbersome process. In the 1990s, Swedish inventor Bengt Wahlqvist developed a new charging technology that would transform the industry. Traditional chargers apply a constant current, risking overcharging and battery damage. Smart chargers, like those from CTEK, use electronic pulse technology to analyse the battery’s condition and adjust charging accordingly, extending battery life and improving performance.

They will typically work through a series of steps to perfectly preserve you car's battery. The first is desulphation, which uses a pulsing voltage to remove sulphates from the lead plates in the battery to help maintain optimum capacity. After that, charging begins and is maintained to around 80 per cent of capacity, before the current is reduced gradually until the battery reaches 100 per cent capacity. It is then tested to make sure it is holding that charge, before a maintenance mode engages and a pulse charge is delivered when necessary to maintain that full charge. That’s not all. A key feature of CTEK smart chargers is automatic temperature compensation, which adjusts charging voltage based on ambient temperature, ensuring optimal performance in both hot and cold climates.

At Racing Green Car Storage, we fit all vehicles with the CTEK MXS 5.0, which is a versatile and proven smart charger that's good value for money (around £89). It's straightforward to use, shows clearly the charge level, offers a range of functions such as reconditioning or setting for an AGM battery or motorcycle and can be clipped or wired to the battery. In our experience, however, an essential accessory is the CTEK Connect Extension Cable, which adds an extra 2.5 metres of length and simply plugs into the charger's existing clips, for just £15.

The Swedish company’s latest innovation is the CTEK CS One. It’s a clever bit of kit that uses Adaptive Charging Technology to automatically detect battery type and condition, adjusting the charging programme for maximum efficiency and longevity. In fact, it’s so clever you don’t even have to worry about matching clamps to positive and negative terminals – just attach the polarity-free clamps and the CS One does the rest. It automatically detects the type of battery, delivers a customised charging program, and even tells you how long until the battery is charged and ready to go. It can also be controlled and monitored using a CTEK app. This makes it the smartest smart charger on the market, an it costs around £169. As Zeal notes, "The CS One is one of the smartest chargers we’ve ever seen. It takes all the guesswork out of charging and ensures your battery gets exactly what it needs."

With modern cars demanding more from their batteries than ever before, understanding proper maintenance, charging, and replacement is critical. Investing in a high-quality battery and smart charger ensures reliability, extending battery life and preventing the inconvenience of a flat battery and visit to the dealership to have a new one programmed. 

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