How things work: Start Stop [VIDEO]

In this segment, we learn more about the basics of the start-stop systems found in some modern vehicles. We learn why they have become more and more popular and also dispel a few of the misconceptions around the way they work and the damage that they may cause.

Estimated reading time: 5 minutes, 8 seconds.

If you can’t watch the video, you can read the video transcription below: Edited for clarity and readability

Welcome to this week's edition of How Things Work. And in today's segment, we're going to be taking you through the workings of the start-stop system that we sometimes find in our latest generation vehicles. So we'll take you through the basics of how it works, why it's introduced into vehicles, and if there are any disadvantages and potential damages that it can cause your vehicle.

So let's kick off first with how the system works. So, basically what we have is we have an oversized starter motor and, connected to that starter motor, we have obviously the brains behind it. So we have a control unit that ties into all the electronics of the vehicle and decides then if the vehicle is going to switch off the engine at any particular point in time. Now, amazingly enough, this system was first introduced by Volkswagen in 1980, but it never really took off until they sorted out all the electronics.

So why do we have a start-stop system in our vehicles because we get a lot of feedback from customers that they don't really like the system? So its main function is to reduce CO2 emissions as well as some other emissions, as well as reduce fuel consumption. Now you might say to me, “But Peter, how much fuel can it potentially save and how many emissions can it reduce?” And ultimately over a period of time, it does add up to quite a lot. So if we’re driving in an urban environment, with a lot of start-stop traffic that we find ourselves in, we can actually reduce fuel consumption by as much as 15%, but it really comes down to how much CO2 we can save.

Now in South Africa, we pay a really small amount of carbon tax if we think about it, you know, so we may be paying on a vehicle that has 185 grams per kilometre emissions of CO2 we'd probably pay about 10 and a half thousand Rands CO2 tax, but, here's the kicker, in Europe the penalties are severe for CO2 emissions and for the same vehicle in Europe, let's take a country like France,  we'd actually be paying close to 10 and a half thousand Euro for emissions taxes. And that's about 180 thousand Rand. And that's not just a once-off fee by the way. So part of the annual licences is a hefty tax to pay on CO2. So now you can start to see the value of the start-stop function. We just hope that the South African authorities don't pick up on that tax in South Africa.

One of the early criticisms of the start-stop functionality was that when the engine stopped, it took a bit of a delay before the starter motor kicked in and the engine started. However, these days the systems are amazing. So by the time that you've taken your foot off the brake before you've even been able to hit the accelerator, your engine’s actually started and in fact, most of the systems now start within 400 milliseconds and 400 milliseconds is how long it takes us to blink our eyes.

Another area of concern that people have is that it might cause damage to both our engine and our starter motor. So once again technology has marched on and there are a few things that have been improved on. So first of all, our starter motor is amazing. Nowadays it can have up to 500,000 cycles and that's up from 50,000 cycles just a few years ago. The second thing that's very, very important is the engine oil that we use in our systems. So these days the engine oil has a few more characteristics that are applied to it. And one of them is to make it a little bit more sticky so that the engine oil remains on the components even when the engine has stopped.

Another area of concern that people have is that this constant starting and stopping of the engine is going to cause premature wear and tear. And that's because we've always been told that the most wear that takes place on an engine is indeed on start-up. Now that's true when the engine is cold, but once the engine’s reached operating temperatures, it actually doesn't matter how many times we start and stop the engine. It's not going to cause any more wear and tear. Of course, there are other areas of our system that have been beefed up, including our wiring harness. And most importantly, our battery has been beefed up to be able to handle the fact that when we have stopped at a robot or a stop street, for example, and our engine’s off, we can still run some of our things like air conditioning, our music,  and if we’re driving at night, our lights.

There are a few versions of the start-stop system. So for example, some vehicles don't rely on just having one battery; they have a second battery that is dedicated just for the start-stop function. My personal preference though is the systems that we find in soft hybrids where we have a 48 Volt battery and a much larger starter motor that we find between the engine and the transmission, but that's just a personal preference.

So that's the basics in terms of how a start-stop function works and as you can see, when the taxes are high on CO2, the system really, really will save you a lot of money at the end of the day.

I hope you found that useful and we look forward to seeing you on future episodes of How Things Work.

To watch the full episode, visit: https://www.facebook.com/LetsTalkAutomotive/videos/?ref=page_internal

Want to know when the next episode is available? Sign up to get notifications straight into your inbox.