Hi AV8TOR,

I am no wizard, but I will give it a try on some of the questions.

"It shows two glow plugs hooked up in series, but with two batteries also hooked up in series. What are the pros and cons of the two connections?? Should I be hooked up in series to my glow driver panel? Wouldn't the plugs require 3 volts, but less amps hooked up in series and therefore not work with the glow driver panel?"

First, I would go with plugs in parallel. Reasons: provides relatively "constant" voltage to each plug (but see discussion of power source, below). Therefore, if one plug is open, the other will still work. In series, the voltage available to one plug is affected by the voltage drop across the other plug. A hot plug (high resistance = larger voltage drop) will drop the voltage available to the colder (low resistance) plug.

Second, you must consider your power source. If it is a simple battery with no voltage or current control, you can treat that as a voltage source and passive resistance in series. As you increase current draw, the voltage will drop because of the loss across the resistance. That drop with low-resistance batteries (e.g., NiCad's) will be pretty small. Plugs in parallel can be run off of just one cell; although, the current drain may exhaust the cell pretty quickly. You can use multiple batteries in parallel to counteract that effect.

In the example you give with plugs in series, you need essentially twice the voltage to get the same current through each plug. That's why the batteries were in series in that simple situation. Look at it as if the plugs were identical. Each plug needs, say, 1.2V to have enough current to heat up. Two plugs in series would need 2.4V across the total to give the desired voltage drop across each one. But say the voltage drop across one plug decreases, then the voltage across the other plug increases, it will try to draw more current, and may over-heat or burn out. Your power source may include electronics to limit current and voltage (see: power panels. below), but some interaction of the two plugs in series will still remain. The adverse consequencies (except for the open plug) may simply be reduiced.

Power panels: As you point out, increasing the voltage may not be possible with your power panel, but to answer that question with certainty, one would need to know more about how your panel is designed. Some panels are "constant current" and automatically adjust the voltage as needed to give a constant current. In some cases, the control is even more sophisticated and provides constant temperature (see: links).

Thus, on the ground, one can use plugs in series or parallel and probably with little difference, depending on how sophisticated the power panel is. For an airborne unit, I think the advantages of a parallel connection would be the controlling consideration.

Here are some interesting links:

http://www.uoguelph.ca/~antoon/gadgets/glow.htm
http://user.tninet.se/~bkg405h/Pulse...lug_driver.htm
http://www.clcombat.info/drivers.html

John