I just purchased an RCexcel ignition BEC for a .60 sized scale warbird with a DLE 20 installed. Naturally space is a concern along with weight. I have been flying the plane fine with a seperate battery for ignition, but thought it would be nice to eliminate it. I have 8 servos installed and was wondering what the best battery , size would be good for this application. Or if any negative experiences, should I avoid the BEC altogether? I have a DaiPhan 2600mah, 6V battery for RX and servos now.

Not familiar with the DaiPhan, but here's how I would do it. I'd use an A123 with 2 voltage taps powering the receiver bus through 2 switches. I would power the ignition BEC with a Y placed on the throttle servo (as it's likely using the least amount of power, leaving the most available anywhere else for the ignition). FWIW

That makes good sense to me as far as placement goes. My question about the IBEC units is a little different. I'm wondering what filtering system is used to keep ignition noise out of the RX? I know this may open up a can of worms.

My own experience, using 2.4 equipment, has been that there's little need for any extra "filtering"? I'm kinda pushing that envelope actually. 2 of my 4 gassers use only (dropping) diodes to supply power to the ignition module (all are wired similar to above). No filtering in the circuit at all, other than an opto switch. All I'm doing with the diodes is assuring the ignition module is getting proper voltage to prevent trouble with that. This info is not meant as an endorsement. I'm just sharing what I'm doing - derived from my own experience and from spending a lot of time reading what some others (that know a LOT more about it) are doing.

I use a diode on the ignition line to drop the voltage. Single battery.

I use seperate batteries on all my gassers. As you have said, (I have been flying the plane fine with a seperate battery ) why mess with it. Putting a BEC in the system is just some other thing that can go wrong. Stick to the KISS system.

Cheers

i havent heard anything bad about IBECS... you can use any voltage you want, and it will regulate it for you... ... this is the one id use http://www.syssaaircraft.net/cart/pc...5&idcategory=2
.. i surf RCU daily and havent read anything bad about them, nor have i heard anything about the one you mentioned

1 A123 2300, two taps. One to a switch then receiver. One to a switch, opto kill, diode, then ignition.

Works like a champ.

Nothing is said about what frequency you are using. I wouldn't try this on a 72mhz fm system.
It will probably work OK on a 2.4 system but I wonder if its worth the 2 oz it saves.
An ignition system pulls a heavy current for a short period of time while it charges. The average current it pulls that you read on a voltmeter is no indication of what it takes to charge. It may be several amps for a short period of time. This puts a heavy strain on the regulator. It may not be able to supply what the ignition system really needs resulting in a weak spark at high RPM.
Its simply not a good idea.

I am on 2.4. The reason for the change is I wanted to add an optical kill. I find them handy. So, I just bought the BEC version to help save weight. I was kind of thinking of throwing a 3s LiPo in there. For this size plane, I am not really interested in adding another switch. This is not a 50cc gasser. Just a small 62" wing. I already have enough crammed in there.

I don't use switches anymore. You can't buy a decent one anymore. I just plug things together when I want to go.
If you have a motor that misses or runs rough on the top end you will know where the problem is.

On the bold, that's exactly why you might want to have 2 of them powering your receiver!!!!

At what point do you add to switches? I mean what sized plane? All of them? Your .40 sized trainer, or your 50cc sized gasser? I have a very heavy duty toggle installed now.

We're talking 2.4, right?
Guys now running with a battery pack for the receiver and a second for the ignition already have 2 switches? If the plane is big enough to carry that setup, and you think it might have enough left over to carry an opti switch, you can add that, do some simple rewiring, and have redundant power, along with twice the available amperage to your receiver and servos? There's no downside to that, and the cost is the price and weight of the opti switch - which is an excellent plan anyway.... pretty easy to justify?

IMHO, the only better setup in planes up through 30-36cc might be a single A123 battery, but that's just me.

Duplicate post. Sorry, on a slow connection.

Duplicate post. Sorry, on a slow connection.

i beg to differ... the badger will fit in a standard "super switch" cut out
http://www.fromeco.org/categories/Switches

50cc on up is where it makes more sense... i have a couple of these switches, one is on a 50cc bird http://www.fromeco.org/Products/04FRCWO-430s/

Single a123, home built, two leads to two switches both going to reciever. Ignition power straight from RX. Use a optokill for ease of stopping the motor if I am not fitting a choke servo, not for more rf protection.

Havea syysa ubec, worked great but dont see the point of one, also used a diode drop down for the ignition in the past, have also stopped doing that as so far have had no ignition failures on three rcxel ignitions and three rcg ignitions on a123 power. I have had one servo fail on a123 power but could notcome toany conclusions over thatas so far it is one servoout of30 to fail on 6 volt plus in 3 years. Pityit was the elevator servo.

I also am not suggesting that others do it my way just posting my results.

Servos on A123 voltage is no big deal. The current drawn by a servo is dependent on its load not the voltage applied unless its stalled.
The ignition ,however, is a different story. the ignition takes the applied voltage(5V) and multiplies it by 6000 to come up to about 30000v. So increasing the applied voltage to 6.6V means the spark voltage increases to 35994V, an increase of nearly 6000V.
This puts a severe extra strain on all of the components in the ignition circuit as well as the spark plug lead insulation and the spark plug itself.
Not a good idea to leave out that diode.

Well what I am getting from all this is most IBECs and what some of what you guys use is a diode based system. As a diode will only flow energy one direction it sounds pretty safe unless the engergy spike is enough to blow the diode then you just have a dead stick situation. My interest in running the IBEC is mainly a lack of real estate in my new 50cc airplane to mount a switch. The capability of being able to shut down the engine in the event of a linkage failure is appealing as well. I honestly have never had a switch failure in 35 years of R/C. Some have. I have no issues running my system off a single MPI HD switch. If I did want extra security ( And I just might ) then I would run a Smart Fly turbo reg with a smart switch. Knowing that at full throttle and RCEXL ignition is going to draw one amp and that under high flight loads you could draw another 5 or 6 depending on equipment used ( I am using my current 50CC5 servo set up as baseline ) Then I would make sure that the system I have in place will deliver 10 amps with a surge to 15 maybe. The regulator I have is wired with a single input of 16 GA wire and dual outputs of 20 GA. The switch and battery will be 16GA too so I feel I'm good with the 15 amp spike.

really.... must be murder on those large scale planes with their 220cc engines running off a lipo through a power box and regulator..
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An aircraft running a lipo with a power box and a regulator is a very poor idea indeed. There are a lot of unnecessary parts to fail there. I notice that the people that do that resort to redundant systems as a matter of choice. Notice the Smart Fly regulator has a fan to keep it cool. What a power waster that is.
There are a number of world class fliers in the club I belong to. A lot of them choose a simple set of A123 batteries with a diode to reduce the voltage on the ignition. Of course they too have redundancy but their overall reliability is much better.

Regulators produce heat. The fan on a Turbo Reg is most likely lighter then a heat sink and draws less then 10MAH. The A123 batteries have the advantage of being able to be charged very quickly were Li-ion can't. I stick with the Li-ions and regulator because I like to have constant voltage to the servos. I wouldn't consider myself a world class pilot ( Maybe regional LOL ) but having servo speed and power changing on me does show up in snaps and point rolls, my timing ends up being different. At the end of the day, I want an airplane that always behaves the same. After 2.4 came out, I stopped using powerboxes. With 72 mhz, it was a way to drive all servos( sometimes up to 13 digitals ) on a seperate power bus to keep RF from getting to the RX via long leads. I may not have needed it at the home field but when one travels to a region of unknown noise floor, its good to have that extra assurance that your airplane is going to work after a 12 hour drive to the contest.

Yes regulators produce heat. That is the wasted power I am talking about. You don't need a fan or a heat sink if you don't have a regulator.
A123 batteries have a very flat discharge curve. You will probably get just as good regulation with them as you do with a regulator. Check the specs of a regulator.
The noise floor of anywhere in the US is very constant unless you get next to a high power RADAR. In that case you would be well advised not to fly.
With a well designed 72mhz receiver it will make no difference RF wise how long the servo leads are. It will have RF bypass capacitors on the servo leads.
A power box merely relieves the receiver from carrying the servo current loads. You need lots of high current servos before you need one. Remember all of the servos don't work at the same time.
All of the latest 72 mhz receivers had its own built in regulator.(For the receiver - not the servos. Its output was around 3.5 volts) They didn't need an external regulator.