NleahciM

Hi - I'm working on putting together a sig kadet senior, and I'm also converting it to electric power. Due to the conversion, alot of parts won't be placed where they normally are placed - which brings me to my question: how long can servo wires be? What about the wires going between an ESC and a receiver? And then the two sets of wires coming from the ESC - motor and battery wires, is it ok for them to be fairly long? I'm thinking that servos are low enough power that lead length is not very important - and that the lenghts I'm worried about (5 feet or so) shouldn't be a problem at all. Also - I think ESC lead going to the receiver length is probabaly even less important, as the leads aren't carrying power as far as I know - only the signal. I expect the battery and motor wires are the main ones that need to be kept short - is there any good rule of thumb for those?

On a related note - I'm coming from RC cars where one uses the ESC to power the servos. But is my understanding correct that even on an electric plane you need to have an onboard battery to power the servos? Also - included with my radio was a switch with three leads coming from it. I'm thinking that this switch goes inline between the receiver and the battery. Then is the third lead for charging the battery?

Thanks!

Edge 540

OK
If you are worried about servo wire length, you could use a "boosted" lead. Check out servocity.com

Many ESC's for planes have BEC (battery elimination circuitry) so you don't need a receiver battery. In a plane of that size though, you could use a receiver pack also for redundancy, or to have a 6v pack, etc.
What you said about the switch is all correct.

michpittsman

My Feedback: (11)

The receiver and servos get their power from the ESC through the lead that plugs into the throttle channel, so long leads will cause a voltage drop over the whole system. Servos will move in slow motion if the leads are excessively long. Make them as short as you can. Jim

NleahciM

Hmm - the manual for my ESC mentions that some of that company's escs have bec, while others don't. It fails to mention if that specific one does or not. Great...

I expect an esc with BEC produces 4.8V. If I were to connect a 6V battery pack to the receiver, would that cause any problems? I mean like will there be a short between the 4.8V and 6V supply since they're both going to the servo power pins, or is there built in protection for this situation?

NleahciM

Well yes certainly all these leads should be kept as short as possible - but when do long leads cause a noticeable voltage drop? 2 feet? 5'? 10'?

ZAGNUT

My Feedback: (1)

long leads are great for conducting noise and causing glitches and reduced range, especially when around a noisy ESC and motor. best to do a couple of mocked-up layouts to test everything at varying ranges and positions with motor running and off.

weather or not you should use a BEC depends on the voltage of your main battery and the amount of servos you'll be driving. on a model this size you should have no problem with the added weight of a dedicated battery for the receiver. doing this will also allow total electrical isolation of the motor/battery/ESC from all radio electronics if needed



dave