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I'm building a glow plug controller, looking for your input.
by
rabbid79
on 01 Feb, 2018 23:02
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Ok, so I've decided to start designing a glow plug controller. I'm looking for your ideas and input. But unless there's something similar to what I have in mind already on the market, please don't be a nay-sayer and tell me how a cheap $2 toggle switch wired up to a 100A relay from a surplus electronics supply store should be good enough. This project isn't about how to do something as cheaply as possible. It's about how to do it as well as possible.
Here are the features that it will definitely have:
Solid state current switching, which means no relays with contacts that burn out. This also means that the duty cycle of the output to the glow plugs can be varied between 0 and 100%. The internal "on resistance" of the MOSFETs used to switch the current is measured in milliohms. That means less voltage drop than a contact-based system.
Adjustable temperature-based glow time.
Adjustable temperature-based or fixed post-glow time and duty cycle. This is to allow for smoother cold engine running. Maybe the output would decrease gradually from 100% down to 0% over the course of a few minutes or as engine temperature increased?
Configuration/status data read and written using NFC from an Android smartphone. It won't be a shiny app, but it will get the job done. (Unless there's an Android programmer who wants to help?)
"Warning" indictor through the existing GP light. Solid is normal, blinking slow or fast means something else? It could also be used as a count-down timer, where it starts out blinking slowly, but then goes faster and faster as it approaches the end time.
Here are the features that it MIGHT have:
Ability to leave the GPs on while cranking, or turn them off while cranking. The idea here is that if they're off while cranking, there's more current for the starter motor. Does anybody know how current old-school GP relays do it?
Current sensing to determine if there's one or more bad GP.
External switch - such as driver's door opening - to pre-heat the system. Let's call this "pre-glow".
Remote keyfob override control - I could go either way on this one. If the GP controller is set up correctly, it shouldn't be necessary, but it might be nice when diagnosing GP problems to be able to heat them using an external trigger?
Individual circuit for each GP - this would have several benefits:
Individual GP current sensing to identify which plugs are bad.
Individually fused with automotive mini or micro fuses. This inproves overall system reliability. It also means cheap, readily-available fuses.
In order to make the system as universal as possible in order to increase sales, support for up to 8 plugs - I'm thinking Powerstrokes here.
So one gotcha on the post-glow time, is how to know if the engine is running. It wouldn't be absolutely necessary to know - I could just assume that after cranking, the engine is running - but it would be nice to know for sure.
One way to do it is to watch the voltage before cranking and after cranking. If the engine is running after cranking, then the system voltage should be higher because the alternator is providing power.
Another idea would be to use the "W" terminal output from an alternator, but I'm not in love with that one.
Thoughts?
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#1
by
RunninWild
on 02 Feb, 2018 10:36
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Honestly i dont see much of a market for this. I think your barebones ecu idea is great. I also think a very basic glowplug controller might sell if it was cheap enough but it seems like you are overcomplicating it. From my personal experience once the engine is started having the glowplugs on or off hasnt made a difference in performance. Granted i havnt ran my engine in extreme cold so i cant comment towards that.
A solid state controller hooked up to a basic 5-10 second timer that is activated by the fuel cutoff solenoid wire would be handy if it was cheap and compact. I just don't think the average person cares enough to have all the extra control you are looking to provide. I have my glowplugs wired individually to a 4 fuse block which is then powered by a trailer solenoid and controlled by a switch on my dash. Total cost was under $40 and it works reliably with the ability to diagnose individual glowplugs.
I just dont think you could make it cheap enough to be able to sell many.
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#2
by
libbydiesel
on 02 Feb, 2018 11:16
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Nice project. I look forward to seeing more. Being able to set post-glow time for mTDI installations. In my experience, TDI's don't need the glow plugs until temps get very cold, but when they do need glow plugs to start, then after starting the post-glow is much more needed than on IDI engines. What are you aiming for as a price for sale?
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#3
by
RustyCaddy
on 02 Feb, 2018 19:38
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This is an interesting idea. Would this setup work well for all glow plugs including those that are self regulating, like Duratherms?
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#4
by
rabbid79
on 02 Feb, 2018 21:00
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I know it doesn't seem like there's much of a market for something like this, but I really think there is. Either way, it's a necessary evil and a frog I'll have to swallow if I want to produce stand-alone ECUs. I don't think it's realistic to say "Hey, buy my ECU, but you need to use a crappy old GP relay that uses 40-year old technology to control your glow plugs."
I've pretty much decided to go with individual GP control/fuses. This might seem like it would complicate things, but I think it's I important to have the GPs individually fused. Plus, being able to use current sensing to tell which GP is bad without trying to remove the bus bar and pulling out individual fuse would also be awesome.
My goal is to keep it under $100. That's for high quality surface-mount electronics, waterproof aluminum enclosure (it's very nice), microprocessor/smart-phone control, customizable pre-glow, glow, post-glow settings, and made in the USA. The only thing that might not be made in USA is the PCBs (bare boards) themselves. It costs about $5 more per board to have those manufactured in the USA.
I might provide large gauge wires with proper connectors for use on the older-style GPs as an accessory. TDI users would need to use their own 4-wire GP wiring harness.
I expect this would work well with all Duraterms. (Unless someone can think of a reason it wouldn't?)
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#5
by
Ruby Doom
on 03 Feb, 2018 16:43
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I'm guilty of just using wire, and a switch, no relay.
Next time I would use a non-latching switch and a relay (as I have very poor memory and often left the plugs on the whole time I drove and after I got out).
While it's nice you are putting in the effort to make the ultimate system, I don't see the point when the crappy old relay just works, just provide the control voltage?
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#6
by
libbydiesel
on 03 Feb, 2018 18:20
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While it's nice you are putting in the effort to make the ultimate system, I don't see the point when the crappy old relay just works, just provide the control voltage?
The points, as has been stated in the thread, would be to have optimized pre-glow and post-glow times, easy diagnostics of burnt out plugs, and a unit that doesn't have contacts that will burn like the stock coil style relays.
I'm guilty of just using wire, and a switch, no relay.
Next time I would use a non-latching switch and a relay (as I have very poor memory and often left the plugs on the whole time I drove and after I got out).
That's a remarkably foolish way to operate the glow plugs. NEVER wire glow plugs to a latching switch, ever. That's a fine way to burn out all four glow plugs in short order along with ruining your battery. Did you at least fuse the circuit? If not, then that's a great way to burn up your car.
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#7
by
ORCoaster
on 03 Feb, 2018 20:17
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Ruby Doom, name says it all. Wire and a switch? How many batteries do you smoke a year with a setup like that. Yose Dah!
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#8
by
RustyCaddy
on 03 Feb, 2018 22:01
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Well, having got off my lazy a$$ and bothering to do a little homework i can see my question was a poor one. Am not a TDI person and looks like TDI plugs are made for varying conditions:
http://beru.federalmogul.com/sites/default/files/ti_04_gb_2014_fm.pdfAlso explains why using an afterglow loom with a pre-1981 electrical system might potentially be why some Duratherms seem to burn out fairly quickly.
Sorry to hijack.
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#9
by
libbydiesel
on 03 Feb, 2018 22:27
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Bosch Duraterms are self-regulating also and are the least prone to burning out if left one for extended periods including when the engine is running. I don't know why you say they tend to burn out. That has not been my experience.
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#10
by
RustyCaddy
on 03 Feb, 2018 23:11
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Don't know why but i don't get much more than 3 years on a set since putting in the most recent engine (IDI). Installed the 1st set in March 2010 and by early summer 2013 three had failed. The next set went in and by December of 2016 two were failed and another very slow to glow hen out of the engine and wired straight to the battery for testing. The next set will be Beru type GN i have on hand. i like the afterglow on the old system, and have upgraded to a 50 amp relay with a 10 amp wire off the battery for current and separate wiring to each plug out of a fuse block. Each is wired to separate plugs with a 20 amp fuse and still using the OEM relay to open/close the circuit to the 50 amp relay. May be that is problem? IIRC some folks say they get 5 or 6 years from a set of Duratherms?? Now i am really hijacking this thread. Sorry about that.
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#11
by
Ruby Doom
on 04 Feb, 2018 09:43
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That's a remarkably foolish way to operate the glow plugs. NEVER wire glow plugs to a latching switch, ever. That's a fine way to burn out all four glow plugs in short order along with ruining your battery. Did you at least fuse the circuit? If not, then that's a great way to burn up your car.
I'm sure teenaged me would blush in embarassment at this
Funny, the glow plugs lasted all thru that car, and on into the next car I put the engine in (in total it lived thru three cars, two Jetta's and a Golf GTi), never really thought about it 'til now, I think I only ever changed the plugs once.
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#12
by
libbydiesel
on 04 Feb, 2018 12:08
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Be forewarned, you used up all of your free passes (luck) already. Any similar behavior in the future will cause serious issues and great expense.
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#13
by
Ruby Doom
on 04 Feb, 2018 13:02
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Probably the best way round to do it.
Back then, I lived 40 miles from civilization, and it was my main, and usually only, driver. This
new one is just for fun, call it a mid-life crisis mobile
Also back then, I could push start it myself, jump in, slam it in gear and go.
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#14
by
ORCoaster
on 04 Feb, 2018 13:42
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When I purchased another older VW pickup this past summer I tried calling it new but had to start referring to it as "vintage". I was confusing people that thought I actually now owned something that wasn't 35 years old when I bought it.
And yes the days of pushing it fast enough to get it in gear and bump start are long gone too. Hence the need for a good battery and glow plugs.