ANYBODY know how to bring a LiFe 3.3v cell down to 1.5v~1.6v for onboard glow heat?
 

I posted this question a week ago in the battery forum and no one answered...surely I can't be the only guy who wants to do this. Would I use a diode? a regulator? resistor? Any advice appreciated.

PS: I experimented by simply placing a 2nd glow plug in the line and a 1000mah 3.3v cell ran them for 15 minutes...REALLY hot...engine ran like a sewing machine. If I had something to cut the output voltage in half, would the cell run 1 plug for 30 mintues?

Thanks

You can use a regulator curcuit. I intend to that for on board glow as well. I bought a DIY regulator kit from an electronics store here. You should be able to get the same thing from radio shack where you are. It is realy simple to build. A few components to solder and you,re ready.

A linear regulator type will act as a variable resistor to keep the output at 1.5V (or whatever it's set to) and disipate the rest of the volts x current as watts (heat) for no real efficiancy gain.

A switching type regulator will turn the full voltage on and off really quickly with the ratio of on-off determining the average voltage. For something as dumb as a glow plug a 555 timer circuit set to switch at a coupled of hundred hertz with a duty cycle about 40% would do just fine..

BJR, could you please elaborate on this curcuit? Do you perhaps have a schematic drawing? I went to the elctronics store and they gave me a linear regulator kit but made no mention of the swicthing mode regulator. This sounds like a better solution.

Hi!
Why do you want on-board glow?? It's not needed on any two or four-stroke glow engine if you set the carb right, mount the tank according to the tank mounting rule and use the correct fuel andf glow plug.!

How about this On-Board Glow Igniter 1.5V 3A
http://www.hobbyking.com/hobbyking/s..._1_5V_3A_.html

On-Board Glow Igniter 1.5V 3A
Specs:
Input: 6v~23v
Output: 1.5v 3A
Dimensions: 22.9x20.3x7.6
Weight: 8g

Ken

I would just simply use a on board glow ignitor and two LiFe cells in series. I have a couple of planes using that setup already.

Ok but how do you get the voltage down?

You could rip the innards out of a power panel.

That crossed my mind!

Well the onboard glow ignitor has its own electronics built in that reduces the voltage down to a safe level for the glow plug. They usually include a circuit for measuring the current flow and adjust it as well, plus they include a circuit that allows you to set the turn on based on the throttle position too.

You can also perform a GOOGLE search for "glow plug igniter schematic" and see if any of those methods that show up will work for you too. Unfortunately some are from another forum though.