Glow Plug Igniter with CONSTANT CURRENT --Oz--

Oz, how can you measure voltage drop on glow plug element? Do you add a resistor in series to glow plug to measure?

It is a standard four probe measurement, I guess.

@Surfer_kris wrote:A good CV glow "driver" is only about $27, complete with battery, charger and clamp, not sure why you want to reinvent the wheel here?

Can you give a link to that driver, I can't read the name from the picture? tia
You asked why, because I like technical challenges, it makes me think and learn (same reason I spun the magnet to 3.8Mrpm). I have already learned from the feedback from the posts here and some quick testing. The reason I like racing is, it's very technical (setup) and it's a real time challenge (controlling the vehicle at the limit).

Levent Suberk: Oz, how can you measure voltage drop on glow plug element? Do you add a resistor in series to glow plug to measure?

simply a voltmeter across the plug, but in the circuit it would be a comparator (or dc-dc Vfb point), comparing to a adjustable voltage (somewhere around 1.2~1.35V). I am used to driving lasers and high powered LED's (both are diodes), the light output is based on the the current (and a little on temp), so my first guess was to just use CC, after some posts and my tests, this was a wrong guess (I need to change the thread name to CV/CC).

Surfer_kris: It is a standard four probe measurement, I guess.

Correct, like I showed in a few posts back. I used the 4 probes to isolate the plug connector resistance from the plug resistance. This gives the most accurate method, but with a good plug connection and decent gauge wire, this is not needed, exactly like rcats does not do.

About the CV voltage setting, a lot of plug drivers just use a sub-c nicd or nimh single cell, both are pretty low impedance (low IR), so they can deliver 50+ amps if shorted, but with ~0.5Ω resistance they can still deliver several amps.

The picture shows the Lipo driven, CV regulated driver from from dynamite rc.
Here is some more info: https://www.horizonhobby.com/product/cars-and-trucks/pit-equipment/miscellaneous-15155--1/li-po-glow-driver-with-battery-and-charger-dyn1926

@Surfer_kris wrote:The picture shows the Lipo driven, CV regulated driver from from dynamite rc.
Here is some more info: https://www.horizonhobby.com/product/cars-and-trucks/pit-equipment/miscellaneous-15155--1/li-po-glow-driver-with-battery-and-charger-dyn1926

Thanks for the link. Looks like a CV regulator (it may or may not have CC mode), the voltage seems a bit high at 1.5V (some plugs are designed around 1.2V). There was a recall for a battery issue (could be a charging issue), reading the reviews, most are negative (but, thats mostly the only ones reviewing it.

Depending on the design of these buck regulators, some have output short circuit protection (OSC), overcurrent protection (OCP). Most regulators with CC mode, it's totally fine to short the output (generally, that is how you set the limit you want). Some cheap chinese dont have these protection and when shorting the output, they let out the smoke.

I've never had any plug designed for 1.2V, they all work better at 1.5V. That's why the small handheld NiMh batteries ones have to be fully charged in order to work well. The performance is quite quickly reduced from there as they approach their nominal voltage value. The Lipo battery ones will work just the same through out its charged state though, as the voltage output is always at 1.5V.

So why do you want to make a CV regulator when they are readily available? I don't see any technical challenge?

I guess some people must get off on all this tech stuff, but in the time it's taken to have this discussion, I could have built the plane, gone to the supermarket and bought my pair of $3 alkaline D cells, wired them up, fired up the engine and enjoyed a number of flights and happily fallen down dizzy a few times, although I think this discussion has made me dizzier than any control line flight I've had.

Not to offend any forum friends, but I'm
with you, Rod. Lets get a drink.
Bob

@Surfer_kris wrote:I've never had any plug designed for 1.2V, they all work better at 1.5V. That's why the small handheld NiMh batteries ones have to be fully charged in order to work well. The performance is quite quickly reduced from there as they approach their nominal voltage value. The Lipo battery ones will work just the same through out its charged state though, as the voltage output is always at 1.5V.

So why do you want to make a CV regulator when they are readily available? I don't see any technical challenge?

A couple weeks ago, I had the idea CC would be better (and I just explained why CV is better a couple posts ago). What fun is buying one for $25 when you can build one for much less and probably better that what the $25 would of got me.

I have to burn a hour of my time on work days for lunch, I choose to do my hobbies during this time (build/test/repair/research/invent or flying). In 2017 I got 250 hours in the air flying with my high preformance quad, 90% was before work and at lunch, the rest on the weekends, so it's not like I am cutting into my flying time as I do research. Different strokes for different folks.

I did a little CV testing, I did not want to go above 1.300V on my 049 plug, it was very bright (maybe because I was indoors), easily enough to start a motor, but I was bypassing the leads (remote sense). I also checked how much voltage drop on the wires and plug connector at 2A, this was with twice the diameter wire than stock wire (0.044" vs 0.022" diam, this is 3 times less resistance than stock wire), it was ~200mV, that is pretty significant (~17%). The style w/o wires has some benefit in this department. Also looking just at the cleaned up connector to plug voltage drop at 2A was 25 to 75mV (12mΩ to 37mΩ).

@dckrsn wrote:Not to offend any forum friends, but I'm
with you, Rod. Lets get a drink.
Bob

Not being critical of anyone.    I'm just baffled by all the tech jargon.  My brain just gets constipated with all this information, when I could be going outside and having some old-man fun.  Life's too short to speculate.  Gotta get doing!

Nothing implied, Rod. My bad.
I was trying to relate. Sometimes topics
get so deep for me(tech-wise), that the
room starts to spin. Oh, to be young and
sharp again. Alas.
Bob

I am in the 50's now, the older I get the faster I was Started RC gliders in 76 with the gentle lady, got into power in 78, started racing rc on=road cars in 81, a lot of slope combat gliders, tried heli's 8 years ago (single gyro), I did not like the expensive and lengthy repairs, tried quads 6 years ago. they are the most technical (electronics/FW/setup and flying), with 6 processors on board, 100+ adjustable parameters, and quite a few adjustments in the new esc's. I pitched in with feedback/suggestions and dataflash logs to help improve the flight control firmware (betaflight). It has been exciting and rewarding time in all my 4 decades of RC, I love the technical side of quads, being able to dial them in to preform to my liking and then pushing them to the limit (just about any direction any time). I do miss racing cars at the top level (dialing them in and driving), but I dont have the time for that anymore and I am just to old now. Everybody has fun differently, fly on.

Very good videos you have. Other than the subject of this topic, this is a very skillfull move:

https://youtu.be/AsRErPnkb8I?t=62

@--Oz-- wrote:
A couple weeks ago, I had the idea CC would be better (and I just explained why CV is better a couple posts ago). What fun is buying one for $25 when you can build one for much less and probably better that what the $25 would of got me.

I suggest that you do some reading up on the subject then, it is the ignorant attitude that I find very strange. People where designing some very good drivers already in the 70-ties. These would regulate on the temperature (resistance) of the glow plug filament. A DYI circuit board with a few components, lots of fun to be had compared to buying a chinese IC that is only CV/CC.

I don't recall anyone using CC, while CV is fine if one knows how to prime an engine correctly.

@Surfer_kris wrote:

@--Oz-- wrote:
A couple weeks ago, I had the idea CC would be better (and I just explained why CV is better a couple posts ago). What fun is buying one for $25 when you can build one for much less and probably better that what the $25 would of got me.

I suggest that you do some reading up on the subject then, it is the ignorant attitude that I find very strange. People where designing some very good drivers already in the 70-ties. These would regulate on the temperature (resistance) of the glow plug filament. A DYI circuit board with a few components, lots of fun to be had compared to buying a chinese IC that is only CV/CC.

Thanks for the insult.  

I prefer not to just copy someone (specially from 50 years ago), I like to invent for the better of the hobby, different strokes.

I just started this thread for creating a "possible" better glow plug igniting solution (via CC) and commenting on what I thought would work best for glow plug driver and why I thought so, all of them are valid (CC does solve all the IR drops on connections and wire) all open for comments/suggestions), except the glow plug properties that I did not completely know till some testing. I am learning.

My $4 cv/cc 20A converter with a couple of 18650 2600mAH cells for $4 will easily compete with a $26 store bought uint for a third of the price, what fun is that?

I got some good results with some quick testing today with CV/CC (with correct settings), cleared a flood (one drop) in less than 4 seconds.

EDIT: Anyone test a RCATS driver how long it takes to clear a flooded plug? I used a eye dropper and used one drop for my test.

OZ,
This is really neat! I'm going to re-read the whole thing one more time. I feel like I missed the bottom-line points. Then I may ask intelligent questions.

Please don't hesitate to add to this thread.

Jim in MS

@ 944_Jim, thanks. Soon I will post a summary of what I have found, no need to reread the thread.

I have gotten side tracked on a telescope project I started last year, it's both HW/FW issue, I am fixing the flawed focus/collimation 3 servo motor/encoder firmware runaway issue. Been reverse engineering it (schematics) and troubleshooting where the flaws are in HW and FW.
Here is a couple of 10", 12" and a 14" in my garage, all rcx400 except the center one is lx200gps. To many projects, not enough time.

@944_Jim wrote:OZ,
This is really neat! I'm going to re-read the whole thing one more time. I feel like I missed the bottom-line points. Then I may ask intelligent questions.

Please don't hesitate to add to this thread.

Jim in MS

I updated the 1st post with a summary, take a look.