keyless push start cranking time using 12v timer delay off relay module

Thread Starter

saintblues

Joined May 15, 2020
27
Hi,

I'm currently working on an old 1977 classic mini project and am installing an Easyguard Push start button system as per this link https://www.amazon.com/EASYGUARD-EC009-K-L-Remote-keyless-Warning/dp/B07GZBS6N1

The Easyguard unit has a max cranking time of 3s when the push start is pressed to start the engine. With the mini being an older vehicle there will be situations where the cranking time would need to be extended. For this I have been suggested to use a 12v timer delay off relay module which can be viewed here https://www.aliexpress.com/item/32858839271.html

The module incorporates an potentiometer which would allow me to adjust the cranking time to between 1-25s.

My concern is that the car may be over-cranked on occasions where the car turns on prior to the set cranking time being fully completed. For example, if I set the crank time to 7 seconds but the vehicle turns on in 5 seconds there will be an over-cranking time of 2s which can cause wear or severe damage to the vehicles flywheel and/or starter-motor etc.

Is there a way I can get the relay module to turn off automatically once it knows that the car has started?

All help is appreciated.
 
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drc_567

Joined Dec 29, 2008
1,156
... Is the ignition the single coil, distributor to plug type that was used in the previous generation if ignition systems?
... If this is the case, one of the main causes for extended cranking times was due to a layer of oxidation deposited on the interior of the distributor cap, specifically at each of the inside electrode terminals. Some manual cleaning of each distributor plug terminal, using an abrasive of some sort, usually resulted in immediate starting of the engine.
... This is not a direct reply to your post, but may be useful.
 

Thread Starter

saintblues

Joined May 15, 2020
27
... Is the ignition the single coil, distributor to plug type that was used in the previous generation if ignition systems?
... If this is the case, one of the main causes for extended cranking times was due to a layer of oxidation deposited on the interior of the distributor cap, specifically at each of the inside electrode terminals. Some manual cleaning of each distributor plug terminal, using an abrasive of some sort, usually resulted in immediate starting of the engine.
... This is not a direct reply to your post, but may be useful.

Yep single coil. Thanks for the info, will keep it in mind.

As its an old hobby car it wont be driven everyday. As you probably know old cars tend to be a pain when they've sat for a while. It can take I while to get them on again. I could just the use the key for the initial "difficult" turn on and then the push button thereafter, but since I'm modernizing the interior and upgrading everything I thought it would be nice to automate this to if its not too difficult.
 

drc_567

Joined Dec 29, 2008
1,156
... A final thought ... check to see if the carburetor mounting bolts to the engine block are snug, as well as the carburetor top cover bolts. It seems that carburetor bolts are prone to become loose, due to compression of the gaskets, and sometimes due to engine vibration.
 

Thread Starter

saintblues

Joined May 15, 2020
27
... A final thought ... check to see if the carburetor mounting bolts to the engine block are snug, as well as the carburetor top cover bolts. It seems that carburetor bolts are prone to become loose, due to compression of the gaskets, and sometimes due to engine vibration.
good idea ill check that. still trying to figure how to automate the module to stop cranking once the car has started
 

drc_567

Joined Dec 29, 2008
1,156
... Understood ... but it seems like a momentary pulse of the starter motor, just a bump, should be enough to get the engine going as long as the engine is in good operating condition. If a long duration starter motor pulse is necessary, then there may be other problems, like compression, fuel flow, spark quality, etc. etc. ... a dirty or clogged air filter is enough to cause a hard start problem.
 
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crutschow

Joined Mar 14, 2008
28,191
Old engines can take longer to start, especially in cold weather and the engine has a carburetor.

If the vehicle has an alternator light that extinguishes when the motor starts, you may be able to use the signal from the lamp to shut off the starter.
The lamp wire going to the alternator will rise to 12V when the alternator starts running, so that voltage could be detected by a transistor to remove power to the delay relay.
 
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Thread Starter

saintblues

Joined May 15, 2020
27
Old engines can take longer to start, especially in cold weather and the engine has a carburetor.

If the vehicle has an alternator light that extinguishes when the motor starts, you may be able to use the signal from the lamp to shut off the starter.
The lamp wire going to the alternator will rise to 12V when the alternator starts running, so that voltage could be detected by a transistor to remove power to the delay relay.
yes the vehicle has an IGN bulb (ignition light). It extinguishes when the car starts.

I've attached the vehicles wiring diagram which shows the full ignition circuit which incorporates the ignition switch (38), starter solenoid (4), alternator (1), starter motor (5), ignition warning lamp (44), ignition coil (39).

how exactly would I wire the transistor so that it removes power to the delay relay?

wiring diagram.png
wiring legend.png
 

crutschow

Joined Mar 14, 2008
28,191
how exactly would I wire the transistor so that it removes power to the delay relay?
The circuit below should work:

Node Wire_NY is connected to wire NY between the alternator and bulb 44.
Node Ign_Power is connected to the 12V from the ignition when it is on.
Node Relay_Power goes to the relay power connection.
The diode D1 is connected to the 12V ground (common).

What the ignition is on and the lamp is lit, the voltage on wire NY should be low enough so that Q1 turns on and powers the relay.

When the engine starts, the alternator starts charging, raising the voltage on wire NY to the battery voltage (the same as the Ign_Power voltage), turning both the lamp and Q1 off, which removes power to the relay.

The diode protects the transistor from any inductive transient from the relay coil.

Note: To help verify that the circuit will work, can you measure the voltage on wire NY when the ignition is on with the engine both running and not running?

1630818063812.png
 
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Thread Starter

saintblues

Joined May 15, 2020
27
The circuit below should work:

Node Wire_NY is connected to wire NY between the alternator and bulb 44.
Node Ign_Power is connected to the 12V from the ignition when it is on.
Node Relay_Power goes to the relay power connection.
The diode D1 is connected to the 12V ground (common).

What the ignition is on and the lamp is lit, the voltage on wire NY should be low enough so that Q1 turns on and powers the relay.

When the engine starts, the alternator starts charging, raising the voltage on wire NY to the battery voltage (the same as the Ign_Power voltage), turning both the lamp and Q1 off, which removes power to the relay.

The diode protects the transistor from any inductive transient from the relay coil.

Note: To help verify that the circuit will work, can you measure the voltage on wire NY when the ignition is on with the engine both running and not running?

View attachment 247297

Thanks for that!

I'm a little confused. When the engine turns on and the alternator charges raising the voltage on Wire NY turning both the lamp and Q1 off thus removing power to the relay. Wouldn't the relay continue to run thereafter due to charge held in the capacitors on the module? If this is the case I would still have the over-cranking issue.

I'm upgrading the engine and interior at the moment so the vehicle is stripped inside etc. It'll be a while before I am able to start the engine and measure the voltage on wire NY.

Regarding the delay off module itself. Which port will the push start trigger wire connect to and which port does the Relay_Power wire connect to? I notice on the module (pic below) there is VCC, SVCC, SIG and PUBLIC.

delay.png
 

crutschow

Joined Mar 14, 2008
28,191
Wouldn't the relay continue to run thereafter due to charge held in the capacitors on the module?
No.
The power holds the relay closed, and there is no capacitor on the board large enough to keep the relay closed for any significant time after the power is removed (the caps are likely for the electronic timing and not even connected to the relay).
Which port will the push start trigger wire connect to and which port does the Relay_Power wire connect to?
This is how it operates according to your referenced page:

Working Principle:

1. Power on the module (12V or 5V) and relay is energized immediately. N.O. terminal is connected to COM terminal.

2. Relay is dis-energized after 0 to 25 seconds. N.C. terminal is connected to COM terminal.

3. Relay keeps dis-energized until there is an external trigger signal.

4. If there is always trigger signal, relay will keep energized until trigger signal disappears, then dis-energized after 0 to 25 seconds. Now N.C. terminal is connected to COM terminal.


The Relay_Power from my circuit goes to VCC on the relay module.

Since the relay is apparently energized immediately after application of power without a trigger being applied, then I would think you would just ground the trigger input.
 
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Thread Starter

saintblues

Joined May 15, 2020
27
No.
The power holds the relay closed, and there is no capacitor on the board large enough to keep the relay closed for any significant time after the power is removed (the caps are likely for the electronic timing and not even connected to the relay).
This is how it operates according to your referenced page:

Working Principle:

1. Power on the module (12V or 5V) and relay is energized immediately. N.O. terminal is connected to COM terminal.

2. Relay is dis-energized after 0 to 25 seconds. N.C. terminal is connected to COM terminal.

3. Relay keeps dis-energized until there is an external trigger signal.

4. If there is always trigger signal, relay will keep energized until trigger signal disappears, then dis-energized after 0 to 25 seconds. Now N.C. terminal is connected to COM terminal.


The Relay_Power from my circuit goes to VCC on the relay module.

Since the relay is apparently energized immediately after application of power without a trigger being applied, then I would think you would just ground the trigger input.
So if I'm thinking right is the following correct:

Relay_Power wire to VCC. The push start buttons Starter wire into NC. The output wire from PUBLIC (COMMON) to the starter solenoid which triggers the starter motor. SVCC and SIG are not used.

When the ignition is turned on by either the push start (1 or 2 push) or the key; the relay will be powered by the transistor. The relay is normally open so the PUBLIC (COM) will be connected to the NO contact internally. Therefore no power will be output through the PUBLIC (COM). When a 3rd push on the push button is applied a signal will travel from the push buttons starter wire to the NC on the relay closing the circuit thus outputting to the solenoid and starter motor via the PUBLIC (COM). The car will crank for the set time as chosen on the potentiometer on the module. If the car starts earlier then the set time; the alternator will simultaneously charge increasing voltage on node wire NY which will switch of the transistor; thus removing power to the relay and opening the circuit again. This will not allow the charge held in the module to continue to pass though even though its meant to continue running as the full timer delay time had not been reached. The module will then deenergize until another signal is received from the starter wire.

Have I understood correctly?
 

crutschow

Joined Mar 14, 2008
28,191
So if I'm thinking right is the following correct:
....................................
If I understand what's happening, not quite.
And I made a error in my thinking so my previous circuit connection designations are incorrect.

Below is how I think it should be connected:
The data sheet says the relay actuates as soon as VCC power is applied, so the Starter_Wire signal is connected to the transistor through the isolation diode D3.
The Starter_Wire signal thus goes through the transistor to activate the Relay, and thus the STARTER through the NO relay contact.
Since the Starter_Wire signal only lasts for 3 seconds, the STARTER signal is also connected to the transistor through isolation diode D4 to keep starter power applied until it starts (turning off Q1) or the relay times out.

This all make sense to you?

1631294459571.png
 
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Thread Starter

saintblues

Joined May 15, 2020
27
This all make sense to you?

View attachment 247670
Appreciate your help!

Hopefully I’ve made sense of your new schematic :

When the ignition is on using the key or push button (1 or 2 push i.e. ign or Acc); voltage runs to the relay module PUBLIC (COM) via node IGN_POWER. Simultaneously node WIRE_NY receives a low voltage (from alternator to ignition lamp wire) connecting to the base pin on the transistor; essentially making the transistor “open”.
Would I be correct here in making the assumption that the low voltage on Q1s base pin does not flow out the emitter and reach the relay module? As if it did, the car would begin cranking over when it shouldn’t.

If we then try starting the car via a third push on the push button. The STARTER_WIRE will output a signal for between 1-3s which will flow through D3 then through Q1 then past D1 and into both VCC and SVCC powering/triggering the relay module to actuate. Upon the relay module receiving this trigger it will output power to the STARTER via the NO. If the vehicle does not start within 1-3 seconds, the STARTER_WIRE signal will stop; however, the car will continue to crank for the set time as set on the relay module (up to a max of 25 seconds); as the relay module continues to get power via the NO output through D4 back to Q1s collector pin.

If the vehicle cranks over and turns on; simultaneously the Alternator will charge WIRE_NY to a higher voltage which will indicate Q1 to turn off removing voltage to the relay module thus turning it off and ending the cranking. Do you think this would be instant? Or is there a possibility of a slight over crank due to a delay between the car starting and the IGN lamp & Relay module switching off?

I also have a few questions out of curiosity:

Why does both VCC and SVCC have to be powered?

What purpose does the R1 250 resistor serve?
I understand resistors lower current and voltage but isn't the node wire_NY already receiving a low voltage when the ignition is on and then raises once the car starts?
 
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crutschow

Joined Mar 14, 2008
28,191
Simultaneously node WIRE_NY receives a low voltage (from alternator to ignition lamp wire) connecting to the base pin on the transistor; essentially essentially making the transistor “open”.
To me, "open" means "off", but the transistor is "on" when its base is low.
A PNP transistor is "on" when its base voltage is lower than the emitter voltage (which it will be when the starter signal arrives).
Would I be correct here in making the assumption that the low voltage on Q1s base pin does not flow out the emitter and reach the relay module?
That's correct.
Both the base-emitter and collector-emitter junctions are reverse-biased by that voltage.
Do you think this would be instant? Or is there a possibility of a slight over crank due to a delay between the car starting and the IGN lamp & Relay module switching off?
It's obviously not "instant" but should be only a small delay, likely not much different from starting it manually.
You'd have to measure the time between the engine starting and the voltage rising to know for sure.
(That would likely require an oscilloscope)
Why does both VCC and SVCC have to be powered?
Because it's shown in the relay connection diagram (below).
Don't know what SVCC does.
1631368053846.png
What purpose does the R1 250 resistor serve?
It limits the current through the base-emitter junction.
The base-emitter junction looks like a diode (in the direction of the arrow), so the current could rise to damaging levels when the Starter_Wire voltage goes high, if not limited by a resistor.
 
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Thread Starter

saintblues

Joined May 15, 2020
27
You'd have to measure the time between the engine starting and the voltage rising to know for sure.
Alright ill make sure to measure this and the other voltage you mentioned earlier once I've got the vehicle to that stage.

By the way would you recommend a different delay module or do you think the one I posted from aliexpress will do the job?
 

Thread Starter

saintblues

Joined May 15, 2020
27
If I understand its operation correctly, it should work fine.
And the resistors, transistors, diodes you've mentioned. Is there any quality difference between different manufactures. would prefer to buy some good quality reliable ones. Any recommendations?
 

crutschow

Joined Mar 14, 2008
28,191
And the resistors, transistors, diodes you've mentioned. Is there any quality difference between different manufactures. would prefer to buy some good quality reliable ones. Any recommendations?
The part brand is generally not critical, but buy from a reputable electronic supplier such as DigiKey, Mouser, etc. (not Ebay, Amazon, or most Asian vendors) to avoid fake parts.
It may cost a little more to order from a reputable vendor, but it's generally worth it.
 
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