BEC with Futaba receiver and Hitec 7950
 

Last night I was attempting to get my rigs set to use 3s or 4s batteries. I'm currently using 2s or NimH batteries connected directly to the servo.

This setup is on my Wraith, but my Honcho will be set up identically if I can figure out what works reliably and glitch free.

The electronics that I am using are these:

Futabe 4PKS
Futaba R603FS or Futaba R614FF receiver
CC BEC set to 7.4v
Axial AE-2 ESC
Hitec 7950TH

I attempted to power the receiver, steering servo and lights (6 LED's total) while having everything directly plugged in (including the BEC) to the receiver. Loading the steering servo anything beyond moderately (even back and forth quickly) will cut the lights, brown out the receiver and lose connection for half a second or more.

I currently have the ESC BEC powering the receiver and lights with the servo powered directly by a power tap at the main battery power wires. Only the single signal wire from the servo is going to the receiver. This setup is glitch free and has taken everything I've thrown at it so far.

The BEC is new (at least 4 months old yet has never been used before). Doesn't mean it's good, but it gives a better chance. I seem to remember something about the new BEC's being revised in one way or another. Larger capacitor is it? A quick search didn't get anything conclusive.

The only way that I can see myself safely powering everything while using 3s or larger is by using two CC BEC's or possibly a large capacitor on the receiver power wires. One BEC powering the receiver and lights and the other powering only the servo. I really don't think I need to be doing this, but I don't know how else to go about setting this to get it glitch free.

Thoughts? Anyone run across this issue with the Futaba receivers? Is it possible the servo truly is pulling anywhere close to the BEC's 10 amp capacity?

Marcus

My son & I both run Futaba's, he has a 4PL & I have a 3PM-x.
We both run the CC 10A BEC direct to the servo (7950's) while the ESC BEC powers the RX.
No issues, we run the BEC black & red to the servo black & red, only servo signal wire to the RX.

For a typical setup, that's a fine setup to run. However. I know the ESC BEC will not be sufficient (or reliable) on 3s or 4s. How you described it is essentially how both my rigs are wired up for use on 2s or NimH.

I can set it up bypassing the ESC BEC, but I'll be fighting glitching issues. Not what I want in a rig I compete with.

Marcus

Ummmm....say what??!!:shock: Both of our rigs are running 3S with the ESC BEC running the RX and the external CC 10A BEC running the servo.
Why can't you do the same??:roll:

NOTE, some radios (mostly Spektrum) can glitch unless the black steering servo wire also runs to the RX along with the servo signal wire.

Apparently I'm getting bad information here somewhere.

Talking with several people, I've gathered that the factory BEC in the AE-2 isn't (wasn't?) sufficient to feed the receiver on 3s+. Rumors that I've heard with the AE-2 is that the BEC is a regulating style that steps the voltage down instead of a switching type like the CC BEC. I'd like to know for sure as I frankly don't want to potentially sacrifice my receiver to find out.

Anyone know what the BEC output is of the AE-2 using higher voltage batteries? Voltage and amperage?

The only additional electronics that I foresee myself installing onto the Wraith is an additional 7950 for 4WS and a winch. I'll need to plan accordingly for these systems as well.

Marcus

You wont find 3s specs for the ae-2, since it's only recommended for 2s.

Why not just traditionally run a BEC, remove the red wire on the esc and go.

Exactly. That's why I'm asking if anyone has checked output on their own. I know a lot of people are still running the AE-2 in their SCX and/or Wraith. Figured someone had to have at least measured voltage alone at one point or another.

Tried it. Glitches and browns out under light to moderate load. First post outlined my issues.

Marcus

The RX will still run the RX just fine on 3s. It just steps the voltage down, it is still in the usable range.

I have diagrams in the Futaba and Wraith threads. Just follow them. This is a simple setup.

That's the kind of answer I was looking for.

Thank you Harley.

I haven't had a chance to mess with the rigs since Sunday, otherwise I would have measured myself. I probably still will just to get some numbers and post back with them next chance I get.


Marcus

I'd like to see the voltage exactly.

With a fully charged 3S Lipo, the AE-2 BEC output is 5 volts exactly.

Now I don't know what kind of amperage it will put out as I don't have a setup to measure current, but I though this was interesting.

Marcus

Re: BEC with Futaba receiver and Hitec 7950
 

Hey guys,

I just ordered a Futaba 4PL with 2 2104 Receivers to run on my Night Crawler and my SC10. I also have Castle Creations BEC's on each vehicle wired as recommended by CC. Will I be able to run 3s Lipo's now on each vehicle assuming all other electronics are stock? Thanks for the help,

Chris

Re: BEC with Futaba receiver and Hitec 7950
 

yeah...u can run 3S lipo as long as u set CCBEC for 6v for steering servo, but it's depends on servo, some servo can handle up to 7.4v.
so make sure u set ur BEC to correct voltage "thumbsup"

Re: BEC with Futaba receiver and Hitec 7950
 

Perfect. I've already setup the CC BEC for 6V, which is what my servos are rated at. If I'm running 3S batteries rated at 11.1V, will the receiver automatically reduce it to a usable range, I suppose?

Chris