DIY automatic start/stop - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

Daox · 03-11-2011, 10:33 AM

I've been thinking more about this and have some additional info. First off, I grabbed a shifter mechanism that I have from a Tercel (same as the Paseo's) and took a look at how I could add a mechanical switch to it to verify neutral position. I came up with nothing at first. Here are some pictures.

So, with not being able to use a mechanical switch like I had planned, I thought of using something like a garage door sensor that stops the garage door if anything interrupts the beam across the bottom. I started looking for those sensors and then thought of yet another idea. What if I just use a LED and photoresistor? That would be more simple, easier and cheaper. So, that is the current plan. I'll mount a narrow beam LED on one side of the plastic housing and a photoresistor on the other end. When the shifter shaft moves up or down into gear it'll allow the light from the LED to hit the photoresistor and change the voltage which the arduino will be able to detect as being in gear. This method should actually be much easier to create/mount versus a mechanical switch.

vskid3 · 03-11-2011, 07:50 PM

What about attaching a magnet to the bottom of the stick and have a reed switch in each of the gear positions? Then when the stick is in gear, it'll activate the switch for that gear, so when none are activated, it'll assume its in neutral. Then you could even have it act differently coming from different gears.

orange4boy · 03-12-2011, 03:49 PM

Sounds like a cool project. Another on the wish list of every EOC-er

How will you control the starter "dwell" (how long it's on for) (edit. answering my own question: the arduino)

I would seriously consider a second vacuum reservoir. Pretty simple to make and worth it for the safety factor.

RobertSmalls · 03-12-2011, 05:09 PM

It makes me wonder what the Insight's neutral switch looks like.

I was thinking about indirect methods like RPM or GPH to detect when you shift in to neutral, but how would you decide when to start the engine back up? Adding a neutral switch is probably the best idea.

Daox · 03-13-2011, 09:31 PM

Quote:

Originally Posted by vskid3

What about attaching a magnet to the bottom of the stick and have a reed switch in each of the gear positions? Then when the stick is in gear, it'll activate the switch for that gear, so when none are activated, it'll assume its in neutral. Then you could even have it act differently coming from different gears.

That would probably work fine. However, I don't think I'll need to differentiate between what gear its in, and I'd also have to mount 6 switches vs just drilling a hole for an LED and a hole for a photo resistor.

I've ordered all the necessary parts and looked over the ignition system schematics this weekend. It doesn't look like I'll be able to just activate the starter unless I bypass the clutch switch which I do not want to do. I could make it work, but it would require a bit more rewiring, and I'm not sure I want to do that yet as I'm not sure how great its even going to work quiet yet.

Daox · 03-14-2011, 11:25 AM

Here is the current schematic that I'll be using. Its pretty simple. If you have any questions, just ask.

edit: almost forgot to add diodes to protect the arduino from the relay coils

euromodder · 03-14-2011, 12:19 PM

I'd put in switches for Neutral and Clutch fully connected (i.e. pedal is in the full up position)

It's the way it's done on Volvo's Drive models.
Start/stop will work with the transmission in neutral and clutch pedal up. (Dunno if they have taken speed into the equation.)

Pressing the clutch pedal instantly starts the engine again.

Daox · 03-14-2011, 12:48 PM

That sounds like a good idea. That would allow the engine start up process to start .5-1 second before you actually get it into gear. This would negate the time penalty for starting a little bit.

Daox · 03-14-2011, 02:44 PM

Alright, here is the new schematic with euromodder's suggestion implimented. It requires a few more components, but thankfully nothing expensive.

The only problem I see here is the largest 6V zener diodes I could find can only handle 5W of power. Now, that 12V is only going to be used for a few seconds at a time, and I am unsure how much power the starter solenoid sucks (I'll have to measure it). So, I'm thinking you may need two or maybe even three in parallel to handle the load. I am not completely sure this will work either due to the diodes all having a slightly different break down voltage. Some input from electronics gurus would be great.

Daox · 03-15-2011, 10:59 AM

I got the bits I ordered last night, so I sat down and started playing with them. The LED is pretty bright, so I might throw a higher value resistor in series with it. No use in using too much power if you don't need to, right?

Also, the photoresistor didn't work exactly as I had thought, so I had to tweak the resistor in series with it to get the photoresistor. It is now a 3.8K resistor instead of a 500k. I'll make a new schematic once I get things mounted and working in the car. That resistor may yet change again as might other things.

Unfortunately, with the change to include the clutch switch signal, I'm going to have to order more parts since I don't have a 5V regulator or any 6v zener diodes laying around. I also still have to figure out if the zener diode thing will even work...