With increasingly stringent environmental regulations, vehicle manufacturers are continuously exploring and implementing clever technologies to reduce fuel consumption and lower emissions. One technology that has gained popularity is the 'smart' or 'intelligent' ECU-controlled alternator, which is now becoming a standard feature in new vehicles.
However, this innovation poses a challenge for those who wish to charge a second battery while driving, as traditional split charge relays are not effective with 'smart' alternators.
What are Smart Alternators?
Smart alternators differ from traditional alternators in that they have their output voltage controlled externally by the Engine Control Unit (ECU), rather than relying on an internal voltage regulator. When the alternator generates a charging voltage, it creates a mechanical load on the engine through the alternator drive belt. As the output voltage rises, the load on the engine increases, demanding more fuel consumption. Traditional alternators maintain a voltage between 13.8-14.4V, resulting in a constant load on the engine and continuous fuel consumption from the alternator.
The advantage of smart alternators lies in their ECU-controlled output, enabling manufacturers to vary the voltage output more flexibly. This allows them to lower the voltage below 13.8V during periods when additional charging is unnecessary, such as when the battery is nearly full. By doing so, engine loads are reduced, fuel consumption decreases, and overall emissions are lowered. This technological advancement helps manufacturers meet industry environmental regulations more effectively.
Another beneficial feature linked to smart alternators is regenerative braking, an energy recovery technology that converts the kinetic energy generated during vehicle braking into electrical energy. Traditional braking systems waste this energy as heat dissipated in brake pads and discs. However, with regenerative braking and the help of smart alternators controlled by the ECU, the alternator voltage output is boosted to as high as 15V+ during deceleration, channeling a burst of charge into the battery. This increased voltage also increases mechanical load on the engine, leading to enhanced engine braking and a reduction in energy converted to wasted heat. Subsequently, the vehicle's deceleration charges the starter battery, saving fuel that would otherwise be needed for recharging.
How does this effect Window Cleaning Systems?
Despite these environmental advantages, the new technologies pose problems for charging leisure batteries in Window Cleaning Systems for a few reasons.
First, during periods when the smart alternator output falls below the charging voltage threshold, no charging takes place. This results in significant portions of a journey where the connected auxiliary battery does not receive as much charge as it would with a traditional alternator system.
Batteries are also sensitive to over-charging. Voltages above 14.4V can cause permanent damage to the battery.
Additionally, Voltage Sensitive Split Charge Relays Relays, commonly used within Window Cleaning, cannot function efficiently with smart alternators. These relays engage and disengage based on specific voltage thresholds, which don't align well with the output behavior of smart alternators. This leads to situations where the auxiliary battery might not charge even though the engine is running.
How to Tell if Your Vehicle has Smart Alternator Technology
To identify if your vehicle has smart alternator technologies:
- Look for eco-efficient branding
-Check the European Emissions Standard compliance of your engine (Euro 5 or Euro 6 onward likely indicates a smart alternator)
- Seek advice from the manufacturer.
A Smart Alternator Workaround
For effective charging with smart alternators, Battery-To-Battery chargers (also known as DC-DC chargers) come to the rescue. These chargers stabilise the highly variable voltage output of smart alternators and maintain a steady voltage according to a multi-stage charging profile, similar to mains chargers.
Beyond overcoming the challenges posed by smart alternators, Battery-To-Battery chargers offer several advantages over traditional split charging systems when used with conventional alternators:
-They enable faster battery charging, achieve a deeper state of charge (around 80% capacity)
- Ensure continuous charging while the engine is running,
- Provide electrical isolation between the starter and auxiliary batteries when the engine is off.
- Protect auxiliary batteries from voltage spikes caused by regenerative braking, preventing damage to sensitive batteries.
-They eliminate potentially damaging current in-rush, which can occur with split charge systems when the auxiliary battery is discharged or very low, and the alternator output exceeds the capacity of cables and fuses.
Battery-To-Battery chargers offer a reliable and efficient solution for charging auxiliary batteries in vehicles equipped with 'smart' alternators. Their ability to stabilize variable voltage output and provide controlled, fast charging ensures optimal battery performance and overall efficiency during your journeys.
Installing them is straightforward, connecting them between the positive terminals of the starter and auxiliary batteries, with a negative connection to the vehicle chassis or starter battery terminal.
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