Hi, i have heard that the ignition battery can make interference to the reciver if it is monted to near, i havnt feel any interference yet but do i have to change position the battery position? here is a picture of it mounted, the lightgreen battery is the ignition battery.

This is the way I look at it. Do a ground check engine off, then do a ground check engine on. If you have more than 10-15% degradation you might have a problem. Be sure to always meet or exceed the manufacturers minimum distance with engine on.

Vlach advises at least 10" distance between any RC or Ignition component.

but what is the difference betwene the reciver battery and the ignition battery?, the ignition box is in the front.

My receiver battery is alongside the receiver and 1 inch away, my ignition battery is about 4 inches ahead of the reciver battery on the same side of the fuselage...Engine is a converted Red Max 42cc brushcutter...Ignition is mine, inside the crankcase, coil is mounted like a G26 under the carb on the outside...Coil is from a G62 with unshielded spark plug wire, rubber cap, resistor spark plug...Futaba 7C radio and receiver..Receiver switch is 4 inches back from the firewall, ignition switch the same distance on the other side..The wire from the ignition switch plugs into the rear crankcase using RCA audio jacks from Radio Shack...The wire from the engine IS shielded to the switch..Nyrod from the throttle servo to the carb....[8D].NO interference.....

nice to hear

The ignition does not have a smooth current draw, it takes a big gulp of battery energy just after the spark fires. This impresses noise on the battery and lead equal to engine RPM.
Your dealing with micro volts of RF signal, give yourself all the edges you can. Cause if you keep cutting corners you will be shouting "I got hit."

In the automotive world there are requirements concerning radiated interference, and conducted interference.
The battery lead picks up the radiated interference, and then conducts it further.

@ Ralph,
Good to hear you have no problem. Would that be a general advice for setup?
My granny lived to be 100, so I canceled my life insurance.

What works for me might not work for someone else....Most ignitions are already shielded, but mine being inside the mount does the same thing cheaper...there are literally thousands of gassers running out there with no shielding at all, Zenoah, Quadra, US engines, etc...
I have no life insurance. I am divorced, no dependents, Uncle Sam will pay for my cremation..
My kids can fight over anything left over....

Ralph- Sounds like you have the world by the ***** on a down hill pull.

I too have not the required distance, and it works for me as well. Yet the ignition manufacturer prefers to play it safe, despite the fact that these ignitions are shielded from elctronics to plug boots, without any opening for the RFI