No problem, I see your point.

Personally I haven't seen or read of any ignition system shorting out, but it's not really something that you're going to hear about on a regular basis. If it were to happen, the person would probably lose the plane, if it was piggy-backed on the receiver battery and would go down as "radio failure" or a "bad battery."

Another thing that could happen that I didn't mention, is a high current draw situation draining the flight pack. For instance, if the spark plug was worn or incorrectly gapped (i.e. excessive gap), that would cause the amp draw to increase quite a bit, and could drain the pack at a faster rate than expected.

This is all strictly opinion on my part, but again, why take the chance when batteries are so inexpensive?

I have never used electronic ignition, but my thumbs probably have more shorts in them....

An IBEC, such as the Tech-aero will limit the current that a shorted out ignition module can draw. While a shorted ignition module is rare, I would not directly hook an ignition module to the receiver bus or "Y" it to the same battery as the receiver without the current limiting and noise filtering that the IBEC provides.
If an ignition module does short out, you'll know it within 1 second, since that's about the time it'll take your engines sudden case of the quiets to reach your position on the flight line, you're not going to be flying around too long with that shorted out ignition.
Pete

+1

You go BarracudaHockey l'm with you...........

thousands of flights- have had ignition develop an internal short and fry the receiver because the ignition and engine switches were located next to each other. Postmortem revealed that when you propped the motor over there was a spark going between the ignition on off switch to the receiver on off switch. One fried receiver was the result as well as a bent plane. One foot of separation between anything ignition and receiver is recommended for a reason... Kind of like checking the chamber is empty when handling a firearm. If you do everything else right it probably wont cause a problem but if you don't and inadvertently pull the trigger. It could be very bad....

Re. the concern about a shorted CDI, have a look:

http://www.youtube.com/watch?v=eTgfkCZ5Dl8

And re. this concern, have a look at this as well:
http://www.youtube.com/watch?v=nw743dZEhsI

TVS suppressors can be made available.

Not testing anything here as you aren't letting the circuit build the voltage necessary to spark with your connection set up. Hook the jumper you are using to form the airgap to the ground lead from your ibec vice the shield wire and see if that causes a problem. Bet something cooks. A stray spark is going to jump to ground not the positive lead coming in. Is there any suppression on the ground side? High voltage can do strange things...

Guys-

I am interested in a single battery in a 30cc Yak I am putting together with a DLE 30 (new HV ignition).

Any thoughts on battery size? I will be using LIFEs.

I was planning on using two by 2300 but that may be overkill.

Larry

1 2300 or 2500 is fine

Great information and excellent video! I guess if you use an IBEC you can go with a single receiver and ignition module battery.

I don't see that much of an advantage other than if you are really tight in the weight department. A good IBEC looks like it's about $40. You could probably get a decent battery and switch for about that much, so price isn't that big of a difference either.

I still like the simplicity of the two battery approach through. All you have there is a battery and a switch instead of a complex electronic device. But, either method seems safe enough for me. I guess it's just a personal preference.

The traditional two battery and switch setup has one safety drawback (OK, glow engines too) If power to the receiver is lost due to a bad connection in the battery or switch harness. No matter what the fail safe setting the receiver provides, the engine will continue at whatever power setting in affect at the time the power to the receiver was lost.
In an IBEC setup, if power to the receiver is lost for any reason, the engine quits immediately instead of continuing at whatever the throttle setting was at the moment the power was lost.
Pete

Good point I hadn't thought of that. That's what i love about these forums, people always come up with ideas you may not have thought of!

I guess the best method would be to use an IBEC setup with dual receiver batteries and switches?

I use two receiver batteries and two switches now on receiver and one for ignition alone.

I know there will be somebody that will say "what if the receiver fails do you have another?" or something of that nature, but I'm just trying to brainstorm the best approach without going overboard.

The RC Excel optical kill does the same thing, loose signal and it kills the engine.

I always want dead stick on signal loss, some argue the point of low idle in fail safe but I'd rather be on the safe side.

@Bchapman - redundancy is great, it just depends on how far you want to take it

So far, from what I have read, I have not changed my plans to put in an optical kill switch/IBE in my Pulse 125 using 1 battery. If I have to wait for a short or some other failure, believe me, the plane might last longer. I have been known to test the life expectancy of my planes.

Andy-

My question above was on using a single 2300 LIFE with a 30 cc yak.

Just for info--I have regular voltage high torque digital servos all around.

I suspect that the ignition probably uses around 200 or so mah per flight.

What do you think I could expect for a reasonable flight time and number of flights before recharging this single battery?

Thanks-

Larry

"I have been known to test the life expectancy of my planes. "
Yeah, they do all seem to come with an expiration date

I just lost my "beater" (8 seasons) 4 Star 60 to failed CA hinges. About 25' off the deck in a shallow dive, the elevator hinges let go. Spectacular full power lawn dart!
My bad for not checking the hinges more frequently
Well now I have a good excuse to get the new 4 Star 64 ARF! Some nice changes to the original design.
Pete

On that setup on a 50cc with a 2300 I was charging every 3 flights (10 to 12 minutes), it would report the battery at 50% capacity when I plugged it in. A few times I would do 4 flights and it would be in the 40 percent range.

Probably could have done more but as fast as they charge, why bother right?

I know what you mean about those CA hinges. On my second flight of my Ultra Stick Lite with a G26 for power, the entire left aileron ripped completely off. How I got it back on the ground with no more damage is the great unknown of my time in this hobby.

I am running a single, LiFe 3000mah, in my Pitts with a Tech-Aero ign cut off. So far I can fly two days, 3 flights each, before recharging. About 1-1/2 hour air time, and not a single glitch to boot.
It is powered by a 55cc twin.
I am so happy with the set-up I am switching my Ultimate over to one battery. It needs replacements.

Or space, .60 size airplanes on the new generation of small gas engines can get tight.

Rats nest topic. The big manufactures DA, OS, and DLE say 8-12 inch spacing between ignition and radio equipment. Is it possible to transmit RF interference through a battery? Dose the battery chemistry play a factor? Rats nest.

this one is good as well http://syssaaircraft.net/shop/syssa-...n-kill-switch/

Same one !!!! they just sell them !!!!

I have three 30cc planes and all have a single A123 6.6 volt of 2300 mah and an Ibec Unit. After 6 flights I generally have to put 800 to 1000 mah back in the battery. Since the charger is less than 100% efficient the actual usage in less. My rule of thumb is to use no more than half the battery's capacity before charging. One 2300 is fine in a 30cc plane.