Throttle weirdness

[njswede]

I just can't seem to catch a break these days. Thought I should re-maiden my rebuilt 71" AJ Slick. It flew just as wonderful as I remembered, except...

Whenever I'm at or near full throttle and move any control surface quickly, the motor stutters. Aileron, rudder or elevator. Doesn't matter which one. But it ONLY happens if I move the stick very quickly.

Setup:
Motrolfly 4330
Castle Creations Phoenix Ice 100A
Castle Creations 20A BEC
4x Savox 1258TG
8s 4000mAh batteries in decent shape.
AR8000 with a single satellite.

Has anyone seen this before? I have another receiver I may try and I'm also thinking of powering the servos from a separate battery.

 

[mnfatboy]

Are you running 4s battery packs in series? If so, how is your BEC wired?

 

[njswede]

Yes, it's two 4s in series. The BEC sees the full voltage, i.e. wired to the same terminals as the ESC.

 

[Jetpainter]

The Talon 90 is only rated for 6S packs. That could be a problem.

They also seem to have more than there share of issues. There are all kinds of threads on the heli sites about them. I have a brand new one that came with a helicopter I bought that I'm kind of shy about using in a heli.

 

[mnfatboy]

Yes, it's two 4s in series. The BEC sees the full voltage, i.e. wired to the same terminals as the ESC.

I've seen problems with the BEC wired to both packs in series but I think Jetpainter might be on to something with the most obvious issue of 8s on a 6s max esc.

 

[njswede]

My bad, it's a Castle Creations Phoenix Ice 100A in that plane and it's rated for up to 8s.

 

[Jetpainter]

The Phoenix Ice has data logging. Do you have a way to check it?

 

[njswede]

Good idea! Although it would require me to find the programming card somewhere in my insane mess... I'll go check if I can find it...

 

[njswede]

Well, I'll be darned! Looks like the BEC is to blame. I plugged a 6.6V LiFe straight into the receiver and the problem went away. Plugged the BEC back in and it started acting up again. Oh well, looks like I'm running a receiver battery in this one. For now, at least!

 

[mnfatboy]

Well, I'll be darned! Looks like the BEC is to blame. I plugged a 6.6V LiFe straight into the receiver and the problem went away. Plugged the BEC back in and it started acting up again. Oh well, looks like I'm running a receiver battery in this one. For now, at least!

Glad you found the issue! I run an RX batt in all plane 70in larger. I've had 1 too many BEC failures and a plane that size can handle the extra weight.