Guys,

I have read other forum postings about running the ignition power directly from the receiver/batteries, but I have a question about my specific setup that I would like to get opinions about.

The other posts that I found mostly talked about running A123 batteries and most were plugging the ignition switch directly into the battery rather than the receiver.

I would like to try out running the ignition power for my DA150/Giles 202/Spektrum AR9000 setup from my receiver batteries.
I have 2 3300mah LiPoly's that are plugged directly into a Emcotec power box (the larger RV/LDO version). The voltage is regulated to 6.0V to the receiver, and 5.9V to the servos/outputs.

I have plugged the ignition switch into a port on the power box that I was not using for anything else and did a range check last Sunday which turned out fine, but I have not flown with this setup yet and plan to do much more extensive range checking before I do.

My questions are:
#1: Is there a possibility that feed back from the ignition would get to the receiver? My understanding is that the Emcotec powerbox isolates the receiver from the servos, but I am not 100% positive on that.

#2: Is there a possibility that the ignition could cause problems with the other servos that are connected to the powerbox?

#3: Has anybody else ran the ignition power from a power box/LiPoly setup? As was mentioned above most of the other examples that I could find were using A123 batts with the power coming directly from a 2nd/3rd battery lead.

#4: The Emcotec unit has a single regulator in it that controls that voltage input/output, is it possible that the ignition could put loads on the regulator that may cause it to overheat? From my understanding ignitions use about 1amp or less load on average, but I don't have any actual test results to confirm that.

I have flown this battery setup for up to a total of 7 flights each 15 to 17 minutes long in a single day and have never put more than about 1,100mah's back into each of the LiPoly's, so I don't see battery capacity as a problem.
I also don't think that the LiPoly's will have any problem handling the amp load needed to maintain the servo & ignition power needs.

Thanks -- Kevod

https://www.flyinggiants.com/forums/...nce-2-4-a.html

I am just trying to find a good reason not to run a separate ignition battery...aside from the extra cost....

Originally Posted by BR289

I am just trying to find a good reason not to run a separate ignition battery...aside from the extra cost....

The reasoning is that I don't necessarily want to invest in a new lipo/lion battery and regulator for the ignition when I already have a battery supply system that is well more than sufficient in the airplane.

I also don't want to have to invest in the charging equipment and batteries for a new A123 battery system unless I convert the entire airplane to A123s which are not compatible with the power box I currently use.

NIMH batteries are not cutting it any more for flight times, so I am trying to resolve that issue.

Here is the main problem that is leading me to look for a solution:
I can fly 2 or 3 10 minute flights and only use about 300 - 400 mah's on the NIMH battery, but the voltage on the NIMH battery drops very fast compared to what I have seen before.

After 1 flight on Sunday my ignition battery tested at 6.0V, but it took less than 200mah to recharge it, and this is happening with multiple different NIMH batteries. After the plane sat for about 30 minutes the battery had recovered to about 6.2V.

Perhaps there is something going on with the ignition unit itself as this did not seem to be the case previously.

Originally Posted by JoeAirPort

https://www.flyinggiants.com/forums/...nce-2-4-a.html

JoeAirPort - check this link out:
https://www.flyinggiants.com/forums/...ing-2-4-a.html

This is where I got most of the information that I am basing any decisions off of.

I currently am running Futaba's 2.4 with a two battery (one ign, one rx) system with both batteries feeding into the RX for redundancy.
Although I can not recommend this, my range checks are the same with or without the ign battery in the rx and I do run a smartfly ignition kill system. I know of people that run both off of one battery without any problems, but I like the added safety of a electronic ign kill.
If you can get a good engine off engine on range check without degradation I would think you are good to go.

Originally Posted by kevod

JoeAirPort - check this link out:
https://www.flyinggiants.com/forums/...ing-2-4-a.html

This is where I got most of the information that I am basing any decisions off of.

I don't care who's doing it, it's a bad idea. I do electrical design for a living and no way Jose. Never will I run an ignition on the same battery as the brain of my plane. Have at it though. Not me.

Originally Posted by JoeAirPort

I don't care who's doing it, it's a bad idea. I do electrical design for a living and no way Jose. Never will I run an ignition on the same battery as the brain of my plane. Have at it though. Not me.

What if it is optically isolated??

How do you transfer DC power across an opto isolated link? I thought opto isolation was more transferring low power signals than passing a large DC current for power. Take for example the Smart Fly ignition cut off. It detects if the receiver voltage goes low via an opto isolated link. But it does not pass power to the ignition through that link. The opto isolator is just a signal transferring device.

You can't, you are right. What was I saying, duh........... I meant, Could you not isolated via diode etc to the ignition lead and use a separate lead from the battery with no back feed.??

Joe, you mean you don't believe in that free energy idea thing, you just grab all you need from the air

Its all about frequency. There is so much electromagnetic radiation in the atmosphere it is incredible. If we didnt use the frequencies we use our planes would never get off the ground.

Just think of a radio dial.

Originally Posted by RTK

You can't, you are right. What was I saying, duh........... I meant, Could you not isolated via diode etc to the ignition lead and use a separate lead from the battery with no back feed.??

Joe, you mean you don't believe in that free energy idea thing, you just grab all you need from the air

That wouldn't work but it would be nice if it were that easy.

There's already enough noise just in the air from the ignition let alone intentionally connect two systems together at the the battery. No matter how many leads come out of the battery, they are still all connected together inside on the battery poles. There's no magic isolator or filter inside the shrink wrap. Look I know people are doing this without crashes but I think it's crazy. I don't think it was the intent of the 2.4G design people. Does it say to do this in their manuals? Like I said, I won't be doing it.

In this day and age of technology there is no way to isolate feed back from one set of wires????

Im with Joe, Bad idea. The reason I would never ever do this is because of an incident that happened to me. With my JR 12X I had an elevator servo short out in flight and send RF or funky currents back through the receiver. All of my control surfaces went nuts, the plane was totally out of control. Lucky the servo shorted quickly and I was able to gain control and land. Afterwards, I did range checks on the ground and they were severely limited. Couldn't get more than 30 feet from my plane before it would lock out.

With the huge volts that ignitions through at that plug, should it short out or whatever I see no reason it couldn't incapacitate your receiver just as my bum servo did. Do what you want, but when something fails you may taking your plane home in a trash bag. Just to much of a gamble.