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Topic: Car idle stop system (Read 230 times) previous topic - next topic


Hi there

Im thinking to make an "idle stop system" for my car, to save fuel during car stop.

I can use arduino for that and it would get information about car speed, rpm from odb2 port and break details from the break swtich. It can control engine start / stop, headlights on/off in night, ac on/off.

I want to know what problems can arise and if anybody has ever tried to make it ?



Vehicles that have this function are especially designed to stop the engine at just over top dead centre so a quick squirt of fuel and a spark gets it started very quickly.

I doubt that you will be able to get your motor started in the same way.

I would also suspect that the insurance company would not be particularly impressed if it stopped at the wrong time.

Arduinos are not rated for life critical situations.



what problems can arise
As well as those already mentioned you will need to deal with the noisy electrical environment of the car.  This could be a particular problem when restarting the engine which takes a lot of current and causes the voltage to drop considerably.  If this is not dealt with by stabilising the voltage supplied to the Arduino it could cause it to reboot just as the car is restarting.
Please do not send me PMs asking for help.  Post in the forum then everyone will benefit from seeing the questions and answers.



I guess you could indeed implement a crude stop start technology in the vehicle. You would need to however work out which sensor type you have fitted, either passive or active type engine speed sensor. Fingers crossed for the Hall effect.

Ideally you would need to create an algorithm based on these ( assuming there fitted.)

Engine Speed - Engine Management
Vehicle Speed - ABS/ ESP/ DSC /ASR etc etc.....
Clutch Pedal Position.
Brake Pedal Switch - ABS - Body Convenience Module

This would fulfil some operational conditions - I.e Engine speed at approximately 750 Rpm, Vehicle speed 0 Mph and Clutch Depressed. ( Vehicle stationary.)Foot on brake, Cut Signal to Coil, When Brake pedal is released & (Optional) Clutch Pedal is released the vehicle would initialise a start proceed.

Also you would need a method of redundancy for safety.

Then use a relay to switch off the ignition source either crank sensor/  camshaft sensor or coil pack signal/s. Consider switch the ( earth side.)
A second relay to engage the starter solenoid wire.

I would assume the Hall Effect sensor easier to script for rising interpret edges, inductive sensor will need some processing....



Motor makers must have spent zillions of various currencies researching this kind of thing. My biggest fear is that without the exhaustive testing they can do, a combination of signals that you hadn't anticipated would cause "unexpected behaviour" and all hell would break loose at exactly the wrong moment.
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Your answer may already be here: https://forum.arduino.cc/index.php?topic=384198.0


Apr 03, 2016, 01:18 pm Last Edit: Apr 03, 2016, 01:20 pm by Paul__B Reason: Afterthought!
In short, don't even think of attempting this project!

You would for one thing, void your accident insurance!

(You recall what "void" means in "C"?  It means "returns nothing"!)


Apr 03, 2016, 01:37 pm Last Edit: Apr 03, 2016, 01:42 pm by docosama
Thanks everybody for comments.

I don't think an accurate commercial system can be made but a system closer to this technology can be possible.

For example,
1. the engine comes to stop only when car gets idle for atleast x no of seconds after travelling for x no of miles.
2. The driver should know that he has to give enough time for engine to get restart after lifting break pedal before releasing clutch pedal.
3. The system should rework only after xx of minutes after first stop-restart cycle.
4. The system should not work in areas with steep up down curves (mountains etc).

The complexity of electronics of the system and insurance issues can b discussed later when we are convinced that this is possible.

Plz comment. Thx


Please re read the previous comments.

Most members will pull out of any project that risks life or limb.


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