Simple Battery Power switch with diode?

[dbtoutfit]

Hi,

I need to have one switch turn on power to my airplane (rc) reciever and also turn on a 1.2v battery for my engines glow plug. I'm guessing I could hook everything up but I need to keep the 1.2v battery from feeding into the 6v pack and visa versa. Some diodes?

Thanks for any help

 

[Pommie]

What you need is a double pole double throw (google dpdt) switch. These are effectively two switches in one package. What I don't understand is that normally you would switch the receiver on permanently but the glow plug would only be powered until the engine is started.

Mike.

 

[rjvh]

What I don't understand is that normally you would switch the receiver on permanently but the glow plug would only be powered until the engine is started.

Mike.

unless it's timed

 

[dbtoutfit]

Man I totally forgot about a dpdt switch I have a few brand new ones I can use.

As far as the glow plug. I am running a 4 stroke engine. To make matters worse it's inverted and it's in my brand new Yak 3D.

I plan to run the glow plug hot at all times. Four strokes have a tendency to die out on low idle and/or on throttle blips no matter how well you adjust the low end or high end needle. I fly 3D and this plane is for competition. Flying
3D, like hovering, requires a lot of throttle input and 1-12 inches from the ground in a hover is not a good place to lose your engine. 4 strokes always have a problem keeping heat in the head compared to a 2 stroke thus why they make deeper glow plugs with a heat bar.

I do have a few 1.2 volt C cell Nicads I could use but due to weight I would rather use a lipo battery. I need 1.2v to heat the glow plug. My lipo I have on hand for this job is 3.6v. Any way to bring this down to 1.2v without burning the other 2.4v to waste?

 

[jpanhalt]

Why not use something like this: **broken link removed**

I have also seen something that senses the resistance of the glow plug and applies heat as needed, but I can't find the exact source right now. Continuous draw may take a pretty good size battery to last a whole flight, and using a linear regulator on a LiPo just throws away the excess energy as heat. John

 

[dbtoutfit]

Why not use something like this: **broken link removed**

I have also seen something that senses the resistance of the glow plug and applies heat as needed, but I can't find the exact source right now. Continuous draw may take a pretty good size battery to last a whole flight, and using a linear regulator on a LiPo just throws away the excess energy as heat. John

1500mah 1.2v c cell should be fine. I may just add a micro servo to a switch for the on board glow plug and turn it off or on with my transmitter.

The time I need it most is at start up and while hovering or other similar tricks.

So the Lipo is a no go since I will have to burn the remaining voltage? Suck you can just bottle neck the voltage down with out throwing away the rest to heat.

 

[jpanhalt]

So the Lipo is a no go since I will have to burn the remaining voltage? Suck you can just bottle neck the voltage down with out throwing away the rest to heat.

A switching regulator essentially does that, but some people have had radio problems with them, and I am not aware of one that makes 1.2 V for the plug. I use a Castle Creations switcher (Castle BEC) in a large electric. You might call their tech service and see what they say. John

 

[dbtoutfit]

Sounds like an option.

I am running digital and not analog system so interference should be 0%.

 

[audioguru]

Years ago, my 2-stroke airplane engines stopped when the glow plug's battery was disconnected. The engine was at a high RPM not just idling. It turned out to be caused by a new fuel that didn't have enough nitro in it.

Maybe you can spice up your fuel instead of carrying a battery.

 

[dbtoutfit]

Thanks for the advice.

I use high quality fuel. This issue is typical of 4 strokes, especially one mounted inverted..

The engine run great and if it was a typical plane I wouldn't give it a second thought but seeing as I will be flying 3D one little blip or worse the engine dies while I'm in a hover a few inches from the ground its going to smack the ground.

Thanks for all your help.

 

[Hero999]

A switching regulator essentially does that, but some people have had radio problems with them, and I am not aware of one that makes 1.2 V for the plug. I use a Castle Creations switcher (Castle BEC) in a large electric. You might call their tech service and see what they say. John

You could make your own switching regulator of course.
https://www.romanblack.com/smps/smps.htm
You'd need to adapt the circuit for the lower voltage though.

Why not just save yourself the bother and use a 2600mAh NiMH cell?

 

[dbtoutfit]

Why not just save yourself the bother and use a 2600mAh NiMH cell?

Yea, I had thought of that. I have a few battery packs rated at 2200mAh AA cells.

I could run 2 or 3 in parallel and bump the 2200 to 4400 or 6600.

Just run a bar across all the tops (+) and then a bar across all the bottoms
(-) right?
keeps it at 1.2 volts and adds the mAh rating per cell, times each battery. Is this correct?

 

[Hero999]

Paralleling battery banks can cause problems if they aren't all charged equally.


You can buy 2600mHA AA cells; you only need one for your glow plug.