[RavenAvi]

One of the country's largest auto makers, Tata Motors, has acquired the patent for developing an auto start-stop system for implementation in it's future manual transmission offerings, which will be immensely helpful in aiding fuel economy with minimal to no-change in driver behaviour.

The conventional auto start-stop system found in manual transmissions today works by switching the engine off as soon as the driver shifts to neutral and releases the clutch pedal. However, most drivers usually keep their vehicles slotted in a gear and keep the brake+clutch pedals depressed, which results in the engine staying on and burning fuel during idling.

The homegrown auto giant had submitted in it's patent application that this new invention will be a solution to save fuel which is unnecessarily burnt when idling at traffic signals, by automatically switching the engine off as soon as the vehicle comes to a standstill. Similarly, the auto stop is prevented from happening when the vehicle is past it's idling speed.

According to a patent document filed by Tata Motors, the auto stop-start control system comprises an electronic controller and an engine starting and stopping system which can start or stop the engine in response to electronic commands.

The electronic controller will have an assembly of digital input blocks for measuring ignition key state, crank position, brake pedal state, clutch pedal state, engine speed and vehicle speed.

The company submitted that various digital sensors like vehicle speed sensor, engine speed sensor, clutch pedal sensor and brake pedal sensor are interfaced with the digital inputs block of electronic controller and analog sensors like battery voltage sensor and coolant temperature sensor are connected with the analog inputs block of electronic controller. The electronic controller is then interfaced with the engine starting / stopping system.

The digital and analog information obtained by the electronic controller through the digital and analog inputs blocks respectively are first stored in the memory block. Using this stored information from the memory block, the semiconductor device does the necessary processing and accordingly generates the signals for starting or stopping the engine. The engine starting/stopping system starts or stops the engine in response to the said signals. After the vehicle comes to a complete stand-still, the electronic controller checks if the engine is running, if so, the controller checks if the engine speed is at idle speed, Tata Motors said.

Financial Express

[DieselFan]

This in my opinion is not a good feature. In most traffic jams when we drive in bumper to bumper traffic we have to use first gear will be using clutch and driving at idling speeds or stationary for few seconds. each time we come to halt the engine will switch off and switch on again. Doesn't this put higher stress on the engine?

[kiku007]

Do people find this feature useful? I found it annoying and turned off that feature whenever I drove a car which had one.

[ashis89]

Even I found it annoying in the Scorpio which I used to drive on a few occasions. I used to switch it off when my cousin wasn't around. My cousin, who owned the car, always insisted that it be on as it increases the FE.
I have a few concerns here.

1. Does it put additional pressure on the starter and the battery? I'm guessing the battery and the starter have specific starting cycles as their finite life. This feature would unnecessarily increase the number of crank cycles. If what I say is true, then what is the net gain from this feature? (Fuel savings - Cost of feature - Cost of premature battery replacement - Cost of starter repair)

2. We always discuss about the importance of turbo-idling in turbocharged vehicles. Even the manufacturers themselves advocate the practice. Doesn't this feature bypass this practice?

[mpksuhas]

These points were discussed many times in XUV page since the vehicle has this feature. As mentioned by you, I too find this feature bit annoying and keep it switched Off. However, each time I give the vehicle for service, they would switch it ON insisting that it will return more mileage.

Originally Posted by ashis89

1. Does it put additional pressure on the starter and the battery? I'm guessing the battery and the starter have specific starting cycles as their finite life.

Yes, logically it would. However, lets hope the manufacturer have factored this too when they calculated the life cycle of the same.

2. We always discuss about the importance of turbo-idling in turbocharged vehicles. Even the manufacturers themselves advocate the practice. Doesn't this feature bypass this practice?

True again, however chances of someone driving in high RPM and suddenly coming to stop is relatively rare. It is possible though, again lets hope manufacturer has factored this and put a check or a time delay in this case.

Since no one is entirely sure about the above mentioned query, I would never be switching on this feature in my XUV. Above that, in city traffic, unless you are awaiting traffic signal to turn green and you are ahead of the queue. You would anyways be inching ahead in small intervals, this negates the usefulness of the feature.

[honeybee]

I guess this feature is meant to be used at traffic signals. Also I think vehicles will have an override switch to allow a driver to disable this feature.

[sagarpadaki]

Sometimes I feel manufacturers build on features for the sake of it rather than evaluating how pragmatic the feature is in the real life conditions. This is one such feature.

[ashis89]

Originally Posted by mpksuhas

Yes, logically it would. However, lets hope the manufacturer have factored this too when they calculated the life cycle of the same.

We can be sure that the manufacturers have not factored in the additional load on the battery since the OE battery is similar to the ones available in the market for other vehicles.

True again, however chances of someone driving in high RPM and suddenly coming to stop is relatively rare. It is possible though, again lets hope manufacturer has factored this and put a check or a time delay in this case.

Here again we know that the timer for start-stop is 4 seconds which is negligible when compared to the ideal idle time. Also it isn't rare for a high speed run to come to a complete halt in today's cities where the roads are wide. Even a high speed highway run followed by a small break will recreate such a situation.

I hope the design team is cohesive and plan these features together keeping in mind the tolerances and life cycle of all the parts of the vehicle and not with some singular aim (as in increasing the FE).

[AutoNoob]

Originally Posted by ashis89

1. Does it put additional pressure on the starter and the battery? I'm guessing the battery and the starter have specific starting cycles as their finite life. This feature would unnecessarily increase the number of crank cycles. If what I say is true, then what is the net gain from this feature? (Fuel savings - Cost of feature - Cost of premature battery replacement - Cost of starter repair)

2. ... turbo-idling in turbocharged vehicles. Even the manufacturers themselves advocate the practice. Doesn't this feature bypass this practice?

Originally Posted by mpksuhas

they would switch it ON insisting that it will return more mileage.

Yes, logically it would. However, lets hope the manufacturer have factored this too when they calculated the life cycle of the same.

Chances of someone driving in high RPM and suddenly coming to stop is relatively rare. It is possible though.

Originally Posted by sagarpadaki

Sometimes I feel manufacturers build on features for the sake of it rather than evaluating how pragmatic the feature is in the real life conditions. This is one such feature.

Originally Posted by ashis89

We can be sure that the manufacturers have not factored in the additional load on the battery since the OE battery is similar to the ones available in the market for other vehicles.

I hope the design team is cohesive and plan these features together keeping in mind the tolerances and life cycle of all the parts of the vehicle and not with some singular aim (as in increasing the FE).

1. I had chance to interact with some starter motor and battery suppliers for some different reasons some 8 years back. During casual discussion, the topic of start stop system and its impact on Starter and battery came up. The common observation was their understanding for need of higher crank cycle life for both to be used in vehicles with Start-Stop feature. They had products to cater the enhanced requirements. It was upto the OEMs to define their requirements and cost targets to arrive at a suitable selection. So, I hope in last 7-8 years technology and capabilities would have improved further.

2. One may or may not find significant 'visible' differences in the starter motor and battery for the two types of systems (with / without Start Stop). So, I can't judge on the parts quality/ endurance limits just by looking at them.

3. On a personal note, I have always questioned the real world efficacy of the start-stop systems (or even the micro-hybrid systems); particularly in the bumper to bumper traffic conditions like in our country.

4. More than that, I question the method of FE measurement and declaration adopted by ARAI itself. Soaking of vehicle at 25±5 deg C before test is non-coherent with Indian conditions. It should be changed to higher value (e.g. 35±5 deg C) to represent real operating conditions for major part of country for most of the year. The current test method was more of a copy-paste job from EU. And I am sure that the automotive lobby will strongly oppose any move to change this basic parameter as that will pull down the 'declared' FE figures significantly.

5. For effect of Start-stop function on turbo-charger, I agree with opinion of mpksuhas.

[GTO]

Originally Posted by DieselFan

Doesn't this put higher stress on the engine?

More than the car, it sure does put stress on my brain . So terribly annoying, especially in a diesel due to cabin shake. I've still to drive a car where the auto start-stop's functioning is seamless. Also, it's not at all practical on a hot day as the air-con compressor goes off!

This in my opinion is not a good feature. In most traffic jams when we drive in bumper to bumper traffic we have to use first gear will be using clutch and driving at idling speeds or stationary for few seconds

Fully agreed. There has to be a minimum idling time before the system kicks in. I hope Tata's patent remains just that and never makes it to production cars.

Originally Posted by ashis89

We always discuss about the importance of turbo-idling in turbocharged vehicles. Even the manufacturers themselves advocate the practice. Doesn't this feature bypass this practice?

Sure does. Imagine redlining an engine, stopping at a junction and the engine immediately goes off. My heart would weep for that turbo.

[tsk1979]

How to make a 250,000kms capable engine blow up in 100,000kms? Install a start stop engine. Frankly speaking, this is not worth it unless you change cars every 50,000kms or so.

[Jeroen]

Originally Posted by tsk1979

How to make a 250,000kms capable engine blow up in 100,000kms? Install a start stop engine. .

Why would it blow up?

Jeroen

[CrAzY dRiVeR]

All the discussion seems to be about the useability of the start stop system? Did anyone understand the patent however?

To me it just sounds so vague! They just seem to be patenting the use of an existing technology, but under some specific conditions (Not requiring a switch to neutral in this case). But there seems to be no real innovation involved here.

Am i missing something?

[VeluM]

As far as I know in India all hybrid systems no matter how mild attract a lower tax slab which automatically bring the cost of the vehicle down. This is why Maruti and Mahindra have such systems installed.

I'm sure no one would complain about lower prices, and Tata will certainly ensure the provision of an override to switch the system off. Not so much to make a fuss about, weeping or engines blowing up being exaggerations 😄

I've experienced the micro-hybrid in the xuv, and found it useful in Bangalore though I understand that people living in the hotter parts (majority) of the country wouldn't appreciate the A.C. cutting out.

Originally Posted by CrAzY dRiVeR

Am i missing something?

Yup, read the details. The system doesn't require you to switch to neutral, and has sensors and logic on various other parameters of engine, battery, clutch position and vehicle speed that decides whether or not to switch off. I would say more complex than a simple neural and zero speed system, although Mahindra also seems to have implemented a delay after a cycle before which the system is inactive.

[tsk1979]

Originally Posted by Jeroen

Why would it blow up?

Jeroen

Its called exaggeration. I was merely mentioning the fact that usage of start stop systems would reduce engine life. You could make the engine more "robust", however any engine with start stop system deactivated would have a longer rife.
Not to mention that NO emissions also rise when hot engines are restarted.