Radio control glow igniter

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Williamoises

Joined Aug 3, 2021
1
I need some help to solve a personal issue. I am a Radio Control nitro car racer and to start the nitro cars you need a glow igniter that usually are battery power and bump box.
My issue is that sometime I go racing or practice and realize my glow igniter is discharge so I either wait for someone else to arrive to the track or head back home.
In my bump box that makes my engine spin to get it going, I use a 3s 8000mah lipo battery and it is 11.1v so I found in Amazon these glow igniter that can be connected to any lipo battery that has a voltage regulator that brings down the voltage to 1.5v which is what us needed for the glow igniter.
So I bought these Amazon to test them with my 3s lipo battery and it work perfectly so I decided to make a 3D printed box for the voltage regulator and change the wiring to have a better wire management.
After I removed the wires and solder new ones the igniter is no longer working, so I thought I might damage it but the readings in the voltage regulator is accurate and the module seems to be working, but I have limited to now electronics knowledge so I bought another and the same thing happen.
After doing some research I found I'm Amazon the DC to DC buck converter set down module so I got one solder the wires hook it to my 3s lipo adjusted the output to 1.5v but the same thing happens. The voltage in the regulator reads 1.5v, at the glow igniter reads 1.5v but when I put the glow plug the voltage goes to 0 and the glow plug does not ignites.
As I mentioned before I have limited to none electronics knowledge but I want to try to figure this out because this is an idea that a lot of people in my RC community are interested so this could be a good opportunity.

Thanks William

The attached picture is the glow igniter that I bought from Amazon. The green regulator came with the igniter that stopped working after I replace the wires and the blue regulator is the buck convertor also from Amazon.
 

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LowQCab

Joined Nov 6, 2012
1,096
A Glow-Plug requires fairly heavy Current, (Amperage, Amps), at a very low-Voltage,
this is hard for most cheap Electronics to deal with,
especially with virtually zero Heat-Sinks to dissipate the generated Heat.

A Glow-Plug is virtually a "Direct-Short" when it's cold,
and only increases its Resistance after it gets up to Operating-Temperature.
This may take less than a Second,
but I'm sure your Buck-Regulator doesn't like this type of abuse.

A cheap Buck-Regulator, like You have, can not be operated in a closed Box,
it barely survives the Heat that it generates out in open-Air.

Any solution that drops ~11-Volts at ~2 or ~3-Amps MUST HAVE a good Heat-Sink because
it is going to be generating at least ~4-Watts of Heat, Minimum,
and realistically, it's probably twice that much Heat.

That's an adjustable-Output Buck-Regulator in the Picture.
It has a "Ratio" of Input-to-Output-Voltages that it will be "happy" with.
It's probably "happiest" when the Output-Voltage is around ~75% of the Input-Voltage,
which would be around ~8-Volts, not ~1.5-Volts.
So, it is under a particularly heavy-strain when it has to put out
its Maximum-Current at only ~10% of the Input-Voltage.
This equals extra-Heat, and reduced-Efficiency.

A Buck-Regulator for this type of application almost needs to be Custom-Built to survive,
or certainly, at the very least, way "Over-Rated", by a factor of ~2 to ~3X,
and with built-in Current-Limiting.
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shortbus

Joined Sep 30, 2009
8,808
A Glow-Plug requires fairly heavy Current, (Amperage, Amps), at a very low-Voltage,
Have model motor glow plugs changed over the years? I ask because back in the day we used the old "dry cell" 1.5 volt batteries the fat tall kind with 2 thumb nuts on top for the wires. Pretty sure they didn't have all that much current/amps in them.
 

LowQCab

Joined Nov 6, 2012
1,096
Those old 1.5V Batteries had 4- "F"-sized Cells, wired in Parallel inside,
(similar to a "D"-Cell, only much bigger),
and were easily capable of delivering ~10-Amps for short periods of time.

They were also available with the Cells wired in Series for a 6-Volt Output.

Most Large-Flashlights back then used to use the 6-Volt version,
and were quite often completely Water-Proof,
and would Float in Water with the Beam shooting straight up.
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As said a glow plug is almost a dead short and needs a beefy source.

For longer than you've been on the planet I've used a rotator with a glow plug output with no problems.

Forget modern buck converters etc as they stop working even if you think they're powerful enough.

get a voltage regulator... the adjustable ones are ideal but I use 5v lm7805 type with silicon diodes in series with the outpu to reduce the voltage to 1.2 ~ 1.5v.

you can get away with a 5amp type but I use 10amp..... use a finned heatsink (doesn't need to be high fins) as the box lid with the regulator bolted to it with insulator between reg and heatsink (mine is old fahioned mica with compo on both surfaces) and the legs are insulated as they go through the heatsink.... I have an isolated plastic cover over the reg to further prevent contact (my reg is in a TO3 package (like 2n3055 types)

the current costing is about £8 $11
 
forgot to say.....

put a reverse diode in parallel to the spinner motor (as close to motor as possible) and 100nf cap in parallel with the diode, both should be high volts (100v dc at least)

do the same to the volt reg output to the glow plug
 

shortbus

Joined Sep 30, 2009
8,808
Those old 1.5V Batteries had 4- "F"-sized Cells, wired in Parallel inside,
(similar to a "D"-Cell, only much bigger),
and were easily capable of delivering ~10-Amps for short periods of time.
None of the ones I ever tore apart were made like that. They were just like a regular D cell, a carbon rod down the middle surrounded with a powder and a zinc can. Now the fakes they make today to replace them in antique stuff are made like that filled with a group of cells wired together.

Image from - https://www.prc68.com/I/No6.shtml
 

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