funnotcrazy

I made a glow driver from micro switch activated by throttle servo at 1/4 throttle or less. Tried a "c" cell & "even a "D" cell but not enough current to make the glowplug
light up. Put 2 "c" cells together & it lights nicely now. Put meter on it & it shows right at 3 volts. Will this burn out glow plug? Left it on for a few mins & checked it a number of times & it looks good. It does have a bit of wire (22 guage) to it as it is a large plane. Engine is inverted & cowled in. Starting it with a regular glow lighter would be dang near impossible.

raptureboy

More than 1.5 v normally. My onboard glow uses a rechargable 1.5 nicad

flyinwalenda

My Feedback: (5)

A typical plug will light-up on a single "C-cell"....1.5v . You should be connecting the two cells in parallel so you are doubling the mah but keeping the voltage @ 1.5. The plug can take 3v but that is only cutting its life short. Of course a plug can take 12v and will burn super bright for about a second !
I suspect you connections are bad or the wire gauge is too small if it won't light on one cell. Or the cell is on the way out.
http://www.geistware.com/rcmodeling/articles/obgpd.htm

a70eliminator

Either C or D cell both are 1.5 volt. Non alkaline rechargeable batteries are 1.2 volt.
Some glow plugs will survive momentary 3volts some will pop immediately.

SrTelemaster150

It's not volts but amps that burn out a glow plug. That being said, much more than 1.5 volts on a single plug or multiple plugs wired in parallel will usually push amperage beyond the 3 amps that is about the maximum what a glow plug will tolerate. There must be some resitance in the circuit to keep amps down as usually 3 volts would burn out a single glow plug in short order. 2 glow pugs in series, negative to the post on 1, postive to the post on the other will need 2 X the voltage to get the proper amperage.

A "Power Panel" has a variable resitor to adjust current to 3a for proper heat by changing the voltage for the proper current for the resistance present.


Glow plug heat wire is usually around 14ga so that 22ga wire is probably where the resistance is located in your set-up..

flyinwalenda

My Feedback: (5)

Didn't want to get too technical before but to expand further a Power Panel uses a pulse-width modulator circuit for the glow plug driver. If you measure the output voltage with a normal meter at the glow driver connectors you will see close to 12v. What the circuit does is pulse 12v to the plug in about 1ms intervals with about a 10ms pause (with no voltage) in between. When you rotate the knob clockwise it shortens the 10ms pause to provide more 1ms pulses for a "hotter plug". That 'whine" you hear from the panel when a plug is connected is the modulation circuit working. If you connected a scope to the output you would see the pulses

funnotcrazy

I cant get much of a reading when plug is powered up, but it is 3v with no load. Have powered up plug (but not run engine) numerous times with no problem. Probably the 5 or 6 feet total (pos & neg) wire is my resistor. How many amps does a couple of Energizer C cells make ? Plug does not look any brighter than with a good glow lighter, but that is not an accurate read I suppose.

flyinwalenda

My Feedback: (5)

A "C" cell usually can supply around 6000mah....some more,some less,
A glow plug when cold draws more current than when it is warm/hot. Somewhere around 3 amps when cold.
A flyer at the field has used a "C" cell with a standard glow plug adapter cable for decades. I keep one in the box in case my glow driver failed and have used it a few times as well .

SrTelemaster150

6' of 22ga wire would have quite a bit of resistance. Use 14 ga & you can drop your voltage.

Lone Star Charles

Assuming that the glow plug circuit draws 3 amps, and that 22 gauge stranded wire has a resistance of about 15 ohms per 1000 feet, the total voltage drop across the wire in your installation will be about 0.81 volts. This does not take into account the voltage drop across your switches or glow plug connections. Suggest that you go with a larger gauge wire as well as make sure that your other connections are very secure.

I_Fly

I think this is good advice. The first thing that stuck out to me was the thin wire when reading the OP. Glow plugs pull a fair amount of power and the thin wire described combined with any other resistance could easily drop the voltage below what is required. Also, if the wire or some connection is causing enough resistance to drop the voltage you may end up with enough heat to create an undesirable effect...

perdo

My Feedback: (61)

I use Fox 2 volt plugs, on everything except 4 strokes. Use and old Glo bee fire plug with a 2 volt rechargeable battery in it and leave it turned all the way up. it lites-em up I go flying.

THERCAV8R

My Feedback: (283)

Simply put Glow plugs are rated at 1.5 volts. except Fox 2 volt plugs. it is possible to get away with a slightly higher voltage but stick with the recommended voltage and you will be OK.

CRX Turbines

I misread the post ...

Lone Star Charles

Seems like that may be exactly what flyinwalenda said. I'm not sure. Can you explain further?

opjose

C cell alkalines produce about 6000-8000mA, ( 6A to 8Amps )and AA's about 2200mA (2.2Amps), so the current capacity @ 3v is far beyond what the glow plugs need.

In testing I've blown new glow plugs immediately with as little as 1.8 volts.

Use one cell, not two.

CafeenMan

If you want to be really anal about it, ANY voltage will burn out a plug eventually.