Hybrid & EV Brakes: Maintenance & Upgrades

The advent of hybrid and electric vehicles (EVs) has brought about significant advancements in automotive technology, not least in the realm of braking. Regenerative braking, a key feature of these vehicles, offers substantial energy savings by repurposing kinetic energy. However, this innovation also presents unique challenges for both drivers and mechanics, particularly concerning the long-term health and performance of conventional braking components. This article delves into the intricacies of regenerative braking, explores the common issues faced by hybrid and EV braking systems, and highlights the aftermarket solutions now available to maintain and even enhance their performance.

Understanding Regenerative Braking

At its core, regenerative braking is a clever system that utilises the vehicle's electric motor in reverse. When the driver lifts their foot off the accelerator or applies the brake pedal, the motor effectively becomes a generator. Instead of consuming energy to drive the wheels, it uses the wheels' momentum to generate electrical current. This recouped energy is then fed back into the vehicle's battery system, either the high-voltage battery or a specialised 12-volt battery, to be used later for acceleration. The intensity of regenerative braking can vary, with some EVs offering driver-selectable modes that can result in surprisingly strong deceleration, even triggering brake lights without the brake pedal being pressed. In some instances, the rate of regeneration is directly linked to the pressure applied to the brake pedal, influencing both the regenerative and the conventional friction brake systems.

The Battery Connection: AGM and EFB

The demands placed on a hybrid vehicle's electrical system by regenerative braking are significant. The brief but intense bursts of energy storage and release mean that a standard 12-volt lead-acid battery is often inadequate, as it can overheat and fail prematurely. To combat this, many hybrids are equipped with AGM (Advanced Glass Mat) batteries, designed to withstand these demanding conditions while maintaining a respectable lifespan. Micro-hybrid cars, which may not feature full regenerative braking but utilise other fuel-saving technologies like start-stop systems, might be fitted with Enhanced Flooded Batteries (EFB). While AGM and EFB batteries are more robust, they come at a higher cost than conventional batteries. It is crucial to avoid downgrading to cheaper, conventional batteries, as this can adversely affect the vehicle's electrical systems, including the start-stop function, and will quickly lead to the failure of the regenerative braking system. Furthermore, replacement batteries often require coding to the vehicle to ensure proper recharging, a process that should not be overlooked.

Conventional Brakes and the Corrosion Conundrum

Beyond the electrical aspects of regenerative braking, the friction brake systems in hybrids and EVs are fundamentally conventional, comprising discs and pads that convert motion into heat. However, the reduced reliance on these friction brakes, a direct consequence of regenerative braking, introduces a significant challenge: corrosion. With less frequent use, especially at higher speeds, the steel or cast iron components of brake discs and pads do not generate enough heat to evaporate moisture. This leads to increased instances of rust. Technicians have observed that EVs, in particular, are more susceptible to rusted brakes. This lack of use can lead to issues such as squeaking or grinding noises that persist even after several applications of the brakes at speed. More critically, severely rusted brakes can bind or stick, especially as they warm up. Drivers might notice their car feeling less free-moving, or observe smoke and a burning smell emanating from a wheel. It is vital to be vigilant for these signs. A simple diagnostic check involves comparing the temperature of the road wheels after a drive; a wheel that feels noticeably warmer than the others could indicate a brake that is not releasing fully. Never touch brake components after a drive, as they can be extremely hot.

The Importance of Brake Fluid Maintenance

Despite the reduced mechanical usage, it is easy to overlook essential maintenance tasks on EV and hybrid braking systems. The brake fluid, typically recommended for replacement every two years, can be an 'overlooked' item even on an EV's service schedule. Brake fluid naturally absorbs moisture from the atmosphere, which can promote internal corrosion within the braking system. Contaminated brake fluid not only accelerates wear but also reduces the braking system's effectiveness, potentially leading to failure. Therefore, adhering to the recommended brake fluid change intervals is crucial, even for vehicles with relatively low annual mileage.

Aftermarket Solutions for EV and Hybrid Brakes

The quiet and smooth driving experience of EVs and hybrids can make brake noise more apparent, as it's no longer masked by the rumble of an internal combustion engine. While worn or corroded components can cause unwanted sounds, the good news is that a number of reputable aftermarket braking companies in the UK now stock brake pads and discs specifically designed for hybrid and EV applications. Brands such as Bosch Automotive Aftermarket, Federal-Mogul (Ferodo), Comline, Delphi, and Meyle offer products that comply with the mandatory European R90 safety standards. For drivers seeking to address noise and corrosion issues, there are also upgrade options. TRW Aftermarket, a leading manufacturer of braking systems, has introduced 'Electric Blue' brake pads, engineered specifically for EVs. These pads aim to minimise noise and vibrations, incorporating rubber-coated accessories during fitting to enhance this effect. TRW also claims that their Electric Blue compound produces less dust, contributing to a cleaner vehicle and reducing the risk of issues like a handbrake sticking. TRW's Electric Blue range reportedly covers 97% of EVs currently on UK roads, with an expanding offering for hybrid vehicles.

Global Aftermarket Perspectives

While TRW is currently a prominent player in the EV brake upgrade market, focusing on noise and corrosion concerns, other companies are also offering solutions. In North America, EV Tuning Solutions provides bespoke EV aftermarket products. They offer packages to restore or enhance performance, including stainless braided flexible hoses, corrosion-resistant GEOMET coated brake discs, and various pad options for Tesla models (including Model S and Model X). They also stock parts from other respected brands like RB Performance, TRW, Zimmermann, and R1 Concepts, which provides parts exclusively for the BMW i3. It is always advisable to ensure that any modifications made to your vehicle are safe, legal, and declared to your insurance provider.

Frequently Asked Questions

Q1: What is regenerative braking?
A1: Regenerative braking uses the electric motor as a generator to convert the vehicle's kinetic energy into electrical energy, which is then stored in the battery. This slows the vehicle down without solely relying on the friction brakes.

Q2: Why do EV and hybrid brakes corrode more easily?
A2: EVs and hybrids use regenerative braking more often, meaning the conventional friction brakes are used less frequently. This lack of use, especially at higher speeds, prevents sufficient heat from being generated to evaporate moisture, leading to rust formation on the brake components.

Q3: Can I use standard brake pads on my hybrid or EV?
A3: While some standard pads might fit, it is highly recommended to use brake pads and discs specifically designed for hybrid and EV applications. These are engineered to handle the unique demands of these vehicles, including potential noise and corrosion issues, and comply with safety standards like R90.

Q4: Which aftermarket companies offer EV/hybrid brake parts?
A4: Reputable companies include Bosch Automotive Aftermarket, Federal-Mogul (Ferodo), Comline, Delphi, Meyle, and TRW Aftermarket (with their Electric Blue range). For North American markets, EV Tuning Solutions is a notable supplier.

Q5: What are the signs of corroded brakes?
A5: Signs include persistent squeaking or grinding noises, especially after braking, and the vehicle feeling less free-moving. A noticeable difference in road wheel temperature after driving can also indicate a sticking brake.

Q6: How often should I change the brake fluid in my EV or hybrid?
A6: It is generally recommended to change brake fluid every two years, even if the vehicle is not used extensively. This is crucial for preventing internal corrosion and maintaining braking system efficiency.

Conclusion

Regenerative braking is a cornerstone of hybrid and EV technology, offering significant efficiency benefits. However, it necessitates a mindful approach to the maintenance of conventional braking components. Understanding the risks of corrosion and the importance of regular fluid changes is paramount. Fortunately, the aftermarket sector is responding with specialised products designed to mitigate these issues, ensuring that the quiet revolution of electric motoring is also a safe and reliable one. By choosing appropriate aftermarket parts and adhering to maintenance schedules, owners can enjoy the benefits of their hybrid or EV for years to come.