Car Engine start button questions

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1556 posts

Uber Geek

#442264 22-Feb-2011 10:14

ArtooDetoo:
Aaroona: Thank you ArtooDetoo for your reply! That actually is making a bit of sense to me. I will read over it again tomorrow when I'm not so tired and mention it to my friend. We're currently brainstorming a couple of ideas and I think this could be a winner.

We're also toying with the idea of the button only working when the clutch is pressed, or the handbrake is applied.

Clutch won't apply to me, as I have a clutchless manual, but to my mate is still possible.

Thanks again for your reply. Very helpful :)

No worries.

Let us know how it works out.

Cheers,
R2D2

you could also use a relay that will supply power when handbrake on but not when handbrake off using handbrake light circuit.

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Aaroona

3196 posts

Uber Geek

#442382 22-Feb-2011 13:19

ArtooDetoo:
riahon:

You could go super rad and have some sort of shield that slides back over the button like a jetfighter where you flick aside a plate, press the button and then is slides back over. That would be cool.

If you also placed the starter button on the right hand side of the steering wheel then the only one that can accidentally press it would be the driver.

The idea of an 'arm/disarm' cover is indeed a good one for preventing accidental activation, but it isn't a fail-safe in the event that some passenger might decide to try it out, which is what the OP was after, I think. And there's a 'cool' factor in having the starter button resemble those found in exotic cars, something I think the OP was also after, and having gone to the trouble of installing it, I doubt he'd want to then hide his work. Rather, I think he'd want it prominently displayed.

But there's much speculation on my part in the foregoing so I could easily be wrong. Pimping one's ride is very much a personal mission, and however it might seem to others, these mods are intensely important to the owner/builder.

Cheers,
R2D2

You are 110% spot on!

After driving my step-dads BMW M3 which has a button start/stop, I knew I wanted one. Though, the stop I'm not worried about, I know that brings in another whole level of difficulty which I'm not ready for at this moment!

So yes, You're right.

Also, for those that are wondering, the car is fitted with an immobiliser (factory standard one though, if that changes anything?) I've heard there are different types of immobilisers.
The car is this side of 2004~ (I dont know the actual year of it though as its not VIN'ed and registered yet).

powerforce

162 posts

Master Geek

#442388 22-Feb-2011 13:38

An immobiliser is basically an electronic switch that stops power to different components on your car when the alarm is armed.

Most factory alarms simply have an immobiliser on the starter - preventing the car from being turned over while the alarm is on.

More expensive aftermarket alarms take that a step further and can have several immobilers stopping power to different parts of the car.

My rx7 for example has 3 immobiliers. One on the ignition, one on the starter and one on the fuel pump.
If any of those 3 connections are not made the car cannot be started.

In all honestly factory alarms are not very secure, im not sure what kind of car you have but I would not be keen to have a stop / start switch with a factory alarm.

heydonms

27 posts

Geek

#443189 24-Feb-2011 21:40

vinnieg: Hmmm, what about finding a start button controller(again not too cheap) so the starter button stops working at voltages above 12.5(with alternator on it'll be roughly 13-15)

This method might cause trouble if you ever need a jump start.

I like the oil pressure option someone else mentioned, it's not perfect, but if your oil pressure drops far enough that the warning light comes on, you probably have bigger problems than a bit of wear on your starter motor.

Aaroona

3196 posts

Uber Geek

#443192 24-Feb-2011 21:51

heydonms:
vinnieg: Hmmm, what about finding a start button controller(again not too cheap) so the starter button stops working at voltages above 12.5(with alternator on it'll be roughly 13-15)

This method might cause trouble if you ever need a jump start.

I like the oil pressure option someone else mentioned, it's not perfect, but if your oil pressure drops far enough that the warning light comes on, you probably have bigger problems than a bit of wear on your starter motor.

But I could use the key, instead in this case. Could I not?

I think Im still liking the handbrake method.

heydonms

27 posts

Geek

#443220 24-Feb-2011 23:13

As long as you leave the key wiring in place, yes you could.

The hand brake isn't a bad one, I've seen other cars that will refuse to start if you don't have the handbrake on or your foot on the break. It is less fool proof than the oil pressure one because you might leave the handbrake on with the car running (e.g. while you go post a letter or something) at which point any passenger who can't keep their hands to themselves can cause trouble.

ArtooDetoo

1044 posts

Uber Geek

Trusted

#443233 24-Feb-2011 23:40

heydonms: As long as you leave the key wiring in place, yes you could.

The hand brake isn't a bad one, I've seen other cars that will refuse to start if you don't have the handbrake on or your foot on the break. It is less fool proof than the oil pressure one because you might leave the handbrake on with the car running (e.g. while you go post a letter or something) at which point any passenger who can't keep their hands to themselves can cause trouble.

Interesting comments and correct as regards the handbrake scenario.

At the risk of stating the obvious, the only bulletproof way of achieving the OP's requirements is that the start button be disabled while the engine is running, since that's the condition when the potential damage will be incurred.

In other words, whenever the engine is running, handbrake on or not, the starter must be disabled.

There may well be many other suggestions besides my own to achieve this, but make no mistake: - it's what the original post requested. The start button must not be able to engage the starter while the engine is running.

So that's your quest chaps and chapettes. And have at it.

Forgive the boldface - simply there for clarity, not shouting.

Cheers,
R2D2

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Nokia2012

108 posts

Master Geek

#443235 24-Feb-2011 23:58

My best advice to you is leave it to the pros I know you want a push button start but come on what is wrong with using the good old turn the key over to start.

I do that in my Subaru starts every time if it an't broke don't fix it.

heydonms

27 posts

Geek

#443237 25-Feb-2011 00:16

In other words, whenever the engine is running... the starter must be disabled.

And there is the crux of the issue, how do you tell when the engine is running? You can't simply check if it is turning over, it does that while cranking and obviously you don't want to disable your starter then.

I suspect the modern cars that do it tie into the ECU and look at a number of variables like RPM, alternator output and maybe the O2 and exhaust sensors. All of these other options are just hacks to achieve a similar result without needing a computer to decode all the inputs and make a decision.

I still reckon oil pressure is the closest you can easily get to something that is always high when the engine is running and always low when it isn't.

heydonms

27 posts

Geek

#443239 25-Feb-2011 00:17

Nokia2012: My best advice to you is leave it to the pros I know you want a push button start but come on what is wrong with using the good old turn the key over to start.

I do that in my Subaru starts every time if it an't broke don't fix it.

Where is the fun in that?

If it ain't broke keep playing with it until it is...

:)

Jaxson

8044 posts

Uber Geek

Trusted

#443283 25-Feb-2011 09:14

Alternator charging seems to fit the bill. There's a battery light on the dash for that.

- Alternator can only charge if the motor is actually turning over.

As I said a while back, get it all hooked up first so it works.
Then once you know you've done that right, hook up a relay to interupt that switch circuit.
Feed this relay with a signal that shows the car is running, taken from whatever point satisfies this and that you can get to.

TheUngeek

924 posts

Ultimate Geek
Inactive user

#443286 25-Feb-2011 09:18

I might have missed it, but what car is it?
I have never heard of a any starter motor burning out from being engaged while the engine is running.
I mean you could do it if you held it long enough... But the noise made would make you stop!

heydonms

27 posts

Geek

#443390 25-Feb-2011 13:35

I mean you could do it if you held it long enough... But the noise made would make you stop!

I guess that depends on the type of passengers you have. I have known people in the past who would be likely to hold the button down just to be d**ks. Of course I wouldn't let that sort of person in my car, but they do exist.

And I suspect that it wouldn't destroy the starter motor so much as the flywheel/flex plate (which is worse since you need to remove the engine or drop the transmission to replace it). I'm not quite sure what the root cause was, but I have seen a motor where the teeth on the flexplate had been worn down to practically nothing because they were grinding against the starter (the starter still looked mostly OK).

TheUngeek

924 posts

Ultimate Geek
Inactive user

#443391 25-Feb-2011 13:37

I have seen that too. It's usually caused by a starter fault.
Starter button in one of my old cars never caused an issue, and it was in easy reach of the passenger seat.

Aaroona

3196 posts

Uber Geek

#443725 26-Feb-2011 21:12

It is a Smart ForFour 2004.

After reading through all these replies, I am thinking that once I get the car on Monday/Tuesday, I may look at hooking it up to the handbrake light.. this vehicle has a VERY simple instrument display, and there is limited options as far as what it shows (doesn't even show the water temp of the car :P)

So, once I get the car back, I will take some photos for you guys and see what you suggest, but the handbrake one is definitely viable.

I've also been thinking about the location of the button, and have found a place I could put it, as long as I could remove my dash to install it. So I will have to see if there is an easy way of doing that, if there is, then cutting the button off from working wouldn't REALLY need to be done, but would still be nice to have that failsafe.

It has to go into Mercedes Benz on Monday so I will see if they can give me an idea on how to quickly and efficiently remove the dash without causing any damage to parts (these cars are literally like kit-sets, you can remove and replace just about anything in it.. but it does cost an arm and a leg to do so, so avoiding doing that would be key)

I do have another thing I want to do now as well... but I will post that in another thread to keep things simple....

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