Leading the charge
Modern battery technology
Stop-start technology, heated seats, climate control, power everything; greater automation and fuel efficiency in cars is placing increasing demands on the unsung hero under the hood – the battery. Here, we compare some of the batteries available on the market today.
A great all-rounder
Most of us are familiar with the more traditional lead-acid batteries in vehicles – where a series of treated lead-based plates are flooded in an electrolyte solution of sulphuric acid and water, creating a chemical reaction that ultimately generates power. They're also known as SLI batteries (starter, lights and ignition).
A portion of an SLI's energy is used just to start the engine. It relies on the continuous running of the engine to deliver enough power to run the car's electrical components, as well as recharging the battery so that it can restart the car again as required.
The production of SLIs is relatively inexpensive and the materials are fairly basic; so for decades they've provided a good, low-cost all-round battery for a wide range of vehicles. Their design however can make them prone to leaks and spills, and they are inherently unable to cope with some of the newer technologies that we’re seeing in the automotive marketplace, particularly the stop-start vehicle (SSV).
At the core of SSV design is a simple fuel-saving reality – if the car's not running, it's not using fuel. The engine simply switches off whenever the vehicle is stationary, for example if it is at an intersection or caught in heavy traffic. It's a highly effective fuel-saving strategy, but spare a thought for the battery…
In heavy traffic, the battery in an SSV may be required to start the engine several times in a matter of minutes, even though the engine's running time may only come in short bursts. Meanwhile, the battery must continue to power the vehicle’s electronics, even when the engine isn't running. Not surprisingly, manufacturers of SSVs and similarly demanding hybrid vehicles have turned to a newer battery technology – the absorbed glass mat (AGM) battery.
A new approach
AGMs were first used in consumer vehicles in the early 1990s, although they had initially been developed for use in military aircraft in the mid 1980's, (as a safer alternative to the older lead-acid batteries, whose acid reservoir made them risky in combat situations). Also known as 'dry' batteries, AGMs use fibreglass mats between each plate which absorb the electrolyte. The whole series is then highly compressed to produce a similar chemical reaction to an SLI, only with less acid.
It's primarily this compression that makes an AGM more efficient than a traditional SLI. The close proximity of the plates reduces internal resistance and increases charge acceptance, allowing the AGM to cycle more frequently and charge more easily – making them an effective fit for SSV technology. AGMs also tend to be more durable; being able to withstand extreme outdoor temperatures and the impact of vehicle vibrations.
Despite these promising characteristics, the use of AGMs tends to be limited to high-end European cars. Essentially, it comes down to cost. Their higher rate of compression usually leads to a higher price. The construction process also comes at a cost. The compression in an AGM necessitates the installation of purpose-built assembly lines and specialty construction equipment, making the production process significantly more expensive.
As technology would have it, we've recently seen the entry of a new player to the automotive battery market – the enhanced flooded battery or EFB.
The happy medium?
Essentially a new and improved version of a lead-acid battery, EFBs represent the happy medium between the old SLIs and the more advanced AGMs; offering both cost-effectiveness and efficiency.
EFBs feature a flooded plate arrangement (similar to an SLI battery). They're compressed (like an AGM battery), but not to the same extent as an AGM. Importantly, they can be assembled using existing SLI battery production lines, which greatly reduces the costs.
In some ways, EFBs offer the best of both worlds – they still have the cycling ability of the AGMs but as they're still a flooded battery, they can accept charge more efficiently than an AGM battery.
Widely used by Japanese car manufacturers in their SSV's for their efficiency and cost-effectiveness, EFB batteries are still an emerging technology here in Australia, having only been introduced around three years ago.
On the road – comparing apples with apples
So how do the three battery types compare? Across all major measures – charge acceptance (the battery's ability to accept charge), cranking amps (how much current the battery is able to deliver) and cycle life (the battery's ability to withstand constant discharging and re-charging ) – AGMs and EFBs outperform the traditional SLIs, even in vehicles that were originally built to run on an SLI.
The newer battery types are more durable than the older SLIs, not only because they're more able to withstand the charging demands of many of the modern vehicles, but also because they're more resistant to general driving conditions (vibrations etc).
From a manufacturer's point of view, AGMs offer more flexibility when it comes to engine design. There's no excess electrolyte floating around in the battery, which means they can be mounted in any position, even upside down. However they're also one of the most expensive options available. EFBs on the other hand, offer a cheaper alternative for those manufacturers looking to achieve cost efficiency.
Either way, these alternatives to SLIs are growing in popularity. Forecasts from major battery manufacturers suggest that by 2020, fifty per cent of battery production will be dedicated to the production of AGMs and EFBs.
What's best for your car?
All cars are built to run on certain types of batteries. SSVs must have newer batteries with compatible cycling capability. For example, SSVs such as the Subaru XV, Impreza (2012 onwards), Mazda CX5, Mazda SP25, and Mazda Skyactiv, all use EFB batteries.
Many of the older cars built to take traditional SLI batteries may also run well on the newer batteries, and the newer batteries may actually last longer in these situations than their SLI counterparts. Should you however make the switch to a newer battery type? And if so, which one?
When it comes to battery care and maintenance, it's no longer just a simple case of looking under your hood and seeing what's what. It's crucial to know what you're dealing with. EFB batteries are impossible to distinguish from conventional SLIs on looks alone, so even the experts may need to look at serial numbers for identification purposes.
Do it yourself (DIY) fans should note, the range of high tech electronic functions in modern vehicles means that DIY battery replacement carries a high risk of voiding the electronics, which then leads to very expensive reconnections and resets, not to mention delays, especially if you rely on a dealer.
Convenience, service and advice – without the hefty price
Fortunately, Club Assist is here to help. We've been providing specialist battery services to automotive Clubs across Australia for more than 26 years, and we're constantly across the latest in battery technology for any car sold in Australia. What's more, through the automotive Club service, our battery specialists can come to you, anywhere, anytime, and run a diagnostic on your existing battery – all at no charge for Club members.
If it's time for a new battery, our specialists carry a comprehensive range of traditional and modern batteries; SLIs, AGMs, EFBs, and more. We've got the expertise and the specialised equipment required to replace modern batteries in newer cars without any risk to your all-important electronics. In fact, all of our batteries either meet or exceed your car's manufacturer specifications, and our work and parts are guaranteed. All this, plus discounted prices for our Club members.