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stop starter motor once engine fires.

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=119726
Printed Date: May 14, 2024 at 9:19 PM


Topic: stop starter motor once engine fires.

Posted By: veryunforgiven
Subject: stop starter motor once engine fires.
Date Posted: January 28, 2010 at 11:56 PM

Hi, I'm new here. I've been searching for an answer to this problem for a while now and nothing here or anywhere else seems to fit. Assume that I have virtually no electronics experience, cuz, that'd be correct.
I have a new diesel generator with electric start. I want to hook it up to a refrigeration thermostat which will just act like a switch. When the Temp. gets to 32 deg.F. the generator will start and because it has two heaters plugged into it, it will then shut off when the temp. reaches 44 deg.F.
What I need is the information that will help me find a relay which will shut off the generators electric starter when it turns on the generator so it doesn't just keep cranking the engine over once it is running AND the proper way to wire this relay in to the starter and switch.
Can anyone help me? I know there must be something for this application, because all remote car starters must have something similar.

Thank you .

-------------
Jim.



Replies:

Posted By: i am an idiot
Date Posted: January 29, 2010 at 12:29 AM
is there an oil pressure switch that would kill the motor if the oil pressure is too low?




Posted By: veryunforgiven
Date Posted: January 29, 2010 at 1:00 PM
Yes, there is.

-------------
Jim.




Posted By: i am an idiot
Date Posted: January 29, 2010 at 2:10 PM

When does that wire read ground?  No oil pressure, or when the motor is running?





Posted By: oldspark
Date Posted: January 29, 2010 at 11:09 PM
A better solution is to treat it like an electric fuel pump - albeit the opposite - when the engine is running, the starter motor shouldn't.

For vehicles etc, the alternator is usually used.
For EFI vehicles, the air-flap can also be used.
For non-diesels, ignition sensing can be used.

Is your diesel running compressors directly?
Does it have an alternator/generator?
Is the some electric tacho or speed sensor?
Is there an air flap or governor etc?


Otherwise oil pressure could be used (providing the switch works & there is pressure - otherwise the starter keeps running until otherwise stopped (even if the engine seizes).

Or some "running" sensor fitted - speed, air vane, etc.




Posted By: i am an idiot
Date Posted: January 30, 2010 at 12:50 AM
Tell me more about this better way, the fuel pump thing.  I am thinking that there is going to be fuel pressure any time the switch is in the on position.  Not just when the generator is running.




Posted By: oldspark
Date Posted: January 30, 2010 at 1:08 AM
No - you misunderstand.

I said to "treat it like an electric fuel pump".

Although oil pressure can be used, it suffers from similar problems as when it controls electric fuel-pumps or their relays - albeit without the same lean mixture, dry injector, delayed kill, and leaking fuel issues! (I have struck many that still use oil pressure!)

Although fuel pumps are a safety requirement whereas oil pressure is merely a warning or reliability issue, the faster response of the fuel pump triggers (charge, air-vane, ignition) has advantages, and for pump control is usually far simpler and more reliable. (IE - charge light control usually just means powering the fuel pump relay from the charge lamp circuit - no extra switches, relays, etc. And it's usually easy to bypass in case of charging failure - namely disconnect the voltage regulator or D+ (ie - the charge lamp circuit). )




Posted By: veryunforgiven
Date Posted: January 30, 2010 at 11:47 AM
Ok, that's all greek to me...
I haven't even gotten this generator running yet, bet when I do, I'll let you know what circuits have power with the switch in the run position and which circuits have power when the engine is actually running.
Like I said... assume I know nothing... posted_image

-------------
Jim.




Posted By: oldspark
Date Posted: January 30, 2010 at 7:09 PM
You know nothing?
But you know there's an oil pressure switch - that's a start (pun intended).

The oil pressure switch alone should solve you problem.


The rest - ie, my stuff - is about what might be a better solution.

It's just that I mentioned how oil-pressure switches were once used to control electric fuelpumps in cars, and I expanded into some of those problems.

But my main point with the fuelpump control example was that nowadays, it is based on a charge signal or an open air flap - both of which occur much quicker than oil pressure - hence able to turn off your starter motor quicker.
(There was more - but that is irrelevant to your situation.)


But see what is there.
It may not have an alternator (to charge a battery or run the load), and probably has no air-flap.
If so, the oil pressure is probably the simplest/easiest way to go.

Don't worry - there are no idiots in this thread (myself excepted!) - a good solution should be forthcoming.




Posted By: i am an idiot
Date Posted: January 31, 2010 at 9:54 AM
i am an idiot wrote:

When does that wire read ground?  No oil pressure, or when the motor is running?






Posted By: veryunforgiven
Date Posted: February 06, 2010 at 6:47 PM
Could you email me for a scan of the wiring schematic that came with this generator?
99ssflstc@hotmail.com
Remove the 99 from the beginning of that addy. That's just to foil the spammers and scammers.

Thanks, Jim.

-------------
Jim.




Posted By: veryunforgiven
Date Posted: February 06, 2010 at 11:29 PM
Or send me your email address to the above mentioned address and I can send you a scan of the generator's wiring schematic.
Thanks, Jim.

-------------
Jim.




Posted By: oldspark
Date Posted: February 07, 2010 at 2:29 AM
In case you are referring to me.... (???)

posted_image


That's based on a typical charge-lamp circuit as used in vehicles and for many alternators (where a charge lamp is often required to guarantee charging - or at least its initiation).

But the alternator regulator's switch could be from an airflap etc, though the air might flap (so to speak) whilst it is cranking.
Keep in mind that this is to control a fuel pump which is required to be OFF when the engine is no longer running.

And in your case you want the opposite - you want something OFF once it has started.




Posted By: veryunforgiven
Date Posted: February 07, 2010 at 2:57 PM
I can scan the Wiring Diagram for this generator, I have one here that came with the generator. If you send me your email addy I will send you the scan so you can figure out what I need. Otherwise, I have no idea. I tried to post this scan but it is too large.
Thanks, Jim.

-------------
Jim.




Posted By: oldspark
Date Posted: February 07, 2010 at 4:35 PM
Done. (ie - now awaiting scan. Hopefully not too many MBs!)

FYI - my dwgs are bmp (drawn in MS Paint LOL!) but usually saved as jpg and then usually resaved as gif for forums or ImageShack (I don't want to waste others server space - that's why I keep my posts short and concise).
And I'll crop and re-scale. (Thanks to IrfanView - IMO another excellent freebie!)
But gif ain't always smaller. Nor is jpeg always smaller than bmp!! png can be good...





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