ORIGINAL: rcmiket
Seems like the ESC/BEC are just not up to the task. I went with the CC BEC and it steps down the voltage from the 7.4 volt LiPo. My main concern is mechanical retracts may bind. Drawing power from the main pack causing major problems. This would have been a bad thing in the air. I would rather be safe than sorry. The Panther is running 7 servos which I felt was a bit much for the stock unit. My F-16 only uses 5 which I was comfortable with and have not issues so far. Its a judgement call by the owner. So far I've made the right calls and am flying and having a good time with no issues. Mike
Mike,
That's a great reason to use another BEC, especially on 4S with a questionable stock ESC/BEC. However, if you're still using the same BEC for both retracts AND RX/flight servos, I think a more reliable/ligther option exists. Did you consider powering the retracts only with the main pack using the stock ESC/BEC and using the CC BEC for the rest of the radio? That way you could use a much smaller battery for the radio (1900 mAH is HUGE !)
With my proposal, if you do jam the retracts, in the worse case you run up a high current which blows the stock BEC and possibly kills power to the fan. However, you still have all flight controls so you could make an emergency landing and probably save the plane. In your present condition, a jam in the retracts will still drain your RX battery, although it seems like you planned for that situation by making the pack extra large. There are many ways to skin this cat of course, but I'm personally inclined to go for less weight and always keep the flight system powered as the number one priority. If this were a much more complex and expensive jet, I'd even consider two BEC's or probably an A123 pack with no regulator directly to the RX. The other BEC may be used to power non vital functions.
The CC BEC would be wired to the RX just as you have it now. The stock BEC would have only the ground wire in common with your RX. The stock BEC power and ground get spliced into your retract servo(s) and the signal to those servos come from the RX as they do now. Of course, be sure the power from the stock BEC does NOT go to the RX via any path (that's the key to sharing two power sources only the grounds are common).
It takes a few minutes to pull some pins, and make a few custom solder connections, but once you get the idea, it's not so bad. One needs to be comfortable with soldering of course.
Anyway, I'm just thinking out loud. Happy new year to you in any case.
Joe