Does My Van Have A Smart Alternator?

Let’s talk about smart alternators!

We’ll let you know what exactly they are, and how they differ from normal alternators.

Most importantly we’ll answer our title questions in full: ‘Does my van have a smart alternator?’ and ‘How do I know if I have a smart alternator?’.

To that end, we’ll advise you about a simple method to check if you have one.

Does my van have a smart alternator

Introducing Does My Van Have A Smart Alternator

Where we dive right into what smart alternators are and answer the question ‘Does my van have a smart alternator?’

What is a smart alternator?

Also known as an ECU-controlled alternator or a variable voltage alternator.

A smart alternator is an alternator which is controlled externally by the vehicle’s ECU (Electronic Control Unit). As a result, this allows for much more variability and control over the voltage produced by the alternator.

In comparison, normal/traditional alternators are controlled internally, by a regulator within the alternator. Therefore, there’s little control over the voltage output of the alternator, and as a result there are inefficiencies.

Why were smart alternators introduced/developed?

In short, to comply with environmental regulations.

The European emissions standards, Euro 5 and Euro 6, place severe restrictions on vehicle manufacturers regarding their CO2 emissions.

To meet these rules, vehicle makers developed smart alternators.

Because smart alternators can vary the voltage to suit the state of the battery, the increased efficiency of battery charging. The resultant reduction of mechanical load on the engine turns into increased fuel efficiency. In turn, this means less carbon dioxide emissions.

How to test if my van has a smart alternator?

Well, there are a few ways you can identify this, before we get to the technical method.

You have a smart alternator if:

1. You have a regenerative braking system

A few years ago, regenerative braking systems were widely advertised as a selling point for vehicles which had them. They made the vehicle more eco-friendly and fuel efficient, both of which are highly desirable and so can be used highly effectively for marketing purposes.

They still have this positive effect, but they’re starting to become a standard feature for newer vans.

Why does having regenerative braking mean that I must have a smart alternator?

Because regenerative braking requires the ability to vary the voltage – with periods of lower voltage interspersed with large bursts of charge at high voltage. And to produce that needs an alternator that is ECU-controlled – in other words, a smart alternator.

The ECU detects the vehicle slowing down (deceleration), such as when you take your foot off the accelerator. Then it boosts the output voltage of the smart alternator to 15 Volts or even more, which provides a large burst of charge to the vehicle battery.

The resultant rise in mechanical load on the engine increases engine braking, so less of the vehicle’s kinetic energy is wasted as heat in the discs and pads.

Therefore, any time the vehicle decelerates, the battery is charging. Which saves fuel that would otherwise have to be used to charge it.

Then, when the vehicle is accelerating or moving at constant speed, that charge can be used to power the electrical components. At these times the smart alternator voltage is lowered to around 12.5 Volts. This reduces mechanical load on the engine, which results in greater fuel efficiency and lowered emissions.

Regenerative braking, then, is an energy recovery technology. It was originally developed for F1 cars, and now is used in all types of new vehicles.

It’s clear then that the highly variable voltage output, with spells of low voltage and spikes of high voltage requires a smart alternator.

2. Your vehicle was manufactured in 2015 or later

The vast majority of vehicles made in 2015 and later will have been manufactured in accordance with Euro 5 / Euro 6.

As we mentioned earlier, that means makers need to meet stricter emissions limits, and so they equip their vans with smart alternators.

3. One of your battery terminals has a sensor attached

That’s because ECU-controlled (smart) alternators need to be able to determine the load coming from the battery. So they need a sensor attached to one of the battery terminals, normally the negative terminal

Variable voltage alternator / smart alternator looks like the below, or some other kind of casing around the terminal (but don’t confuse it with the bright red cap that lifts up that some cars have- that’s just a cover).

Battery sensor for a smart alternator

If your van has a normal alternator, you’ll most likely have normal battery terminals, like the below pic.

Battery terminal for normal alternator

How Do I Know If I Have A Smart Alternator?

If you don’t know if you have any of the above or you’re not sure about them, there’s another way you can check to see.

The Testing Method

You can also test to answer the question ‘Does my van have a smart alternator?’

Fortunately, it’s not too difficult to perform the test and find out. You just need a vehicle battery tester, or a multimeter.

Here’s how to do it:

  1. Start the engine of your van. Turn off all electronics – radio, light etc.
  2. Connect the clamps and take the voltage reading using the battery tester/multimeter.
  3. Leave the car running for around 5 minutes. This allows the battery voltage to reach a steady level.
  4. Take the voltage reading again.

If your test results are around 14.2-15V, then you have a traditional/normal alternator.

If your test results are around 12.5-13.5V, then you have a smart alternator.

Simple as that!

Smart Alternator & Charging Auxiliary Batteries

If you have a smart alternator, then you’ll definitely need a DC to DC / battery to battery charger (what is a battery to battery charger?), such as this CTEK DC to DC charger. That’s the only way to charge an auxiliary battery (like this Superbatt leisure battery) from your vehicle alternator.

That’s because the output voltages produced by a smart alternator are at the wrong values (at any moment too high or too low) to work with the split charge relays (Voltage Sensitive Relays) that have traditionally been used for dual battery charging.

We wrote a whole article on this topic: Smart Alternator: Split Charge Relay Won’t Work (For Dual Battery).

Here’s a simple breakdown describing how to know if you have a smart alternator:

How do I know if I have a smart alternator

Summing Up ‘Does My Van Have A Smart Alternator?’

As you’ve just read, there are a few ways to tell if your van has a smart alternator.

If you’ve got regenerative braking then you have one. That’s because this system needs variable voltages that are only possible with an ECU-controlled alternator.

A vehicle manufactured post-2015 makes it very likely you have a Variable Voltage Alternator, since new vehicles have to comply with Euro 5 and Euro 6 emissions regulations.

Finally, a sensor on your negative battery terminal is likely to be to provide the voltage information required by a smart alternator.

And if you’d like to test to prove it, there’s a fairly simple test using a battery tester that will establish it one way or the other.

Thus you’ll have the the answer to the question ‘Does my van have a smart alternator?’.