I was curious about this because I want to run 3S thru the ae-2 .
That's how I got JUNKFOOT set up. 3S/1300m, 16/87, AE-2, 30t Intensity, CC BEC direct to servo. Runs fine.
I have my bec wired just the way the diagram shows.
Which diagram?
It comes off the esc plug into the receiver. But it does not regulate power going to ESC it regulates power going to the receiver,
Huh? If I'm understanding you, that's the same way I have my CUCV set up. That one's a Micro Sidewinder/Holmes 35t, 14/87, but still runs fine on 3S.
..... so how does this protect your ESC from 3S?
The AE-2 has a small BEC built into it, and will take voltage off the main battery pack and feed the receiver. The servo takes what it needs from the receiver. As you start putting servos in that draw more power, the receiver starts asking for more power, and the small built-in BEC in the ESC becomes overloaded. When it just can't put out enough power, the voltage going into the receiver drops, and when it gets low enough, the receiver stops working (aka 'browns out'). As you step up to 7+ cell NiXx packs, or 3S LiPo, the built-in BEC just gets absolutely obliterated much quicker. I, personally, don't like overheating built-ins as I think they can take out other control areas in the ESC just by being in proximity to an overheating component.
When you choose to power your receiver and servo with an external BEC, you would plug the BEC into an open slot on the receiver, AND you're supposed to remove the small red wire from the ESC/receiver connector. Once you remove that red wire, the internal BEC no longer has a complete circuit, and is electrically isolated, and cannot overheat. If you leave that red wire in the connector, then both the external and internal BECs are trying to feed in power. Yay! Extra power! Right? Uh, no. Once the internal BEC feeds power in, the external BEC senses power already on the circuit, switches off, and you're back to square one.
If you connect your external BEC to power only the servo, then the receiver would not have power, and you'd need to leave the small red wire in the ESC/receiver connector. From what I can find, receivers, by themselves, typically only draw 1/4 to 1/2 an amp. And with no moving parts in them, there's nothing to 'stall-out' and spike the amp draw. So even the sketchiest of internal BECs should be able to handle that. LEDs are also pretty constant, so those I'd likely trust to an internal BEC. People do run their winches off the internal, but if I had an external BEC for the steering anyway, I'd throw the winch on the external, too.
Or is there a way to wire it so that your controlling voltage directly to the ESC?
No, typically. Once the power comes out of the battery and enters the ESC, electrons flow through the internal BEC, and come out on the red wire to the receiver. At that point, the voltage is as 'regulated' as the internal BEC is going to get it. Can you connect your external BEC between the ESC and receiver? Yes, but that doesn't fix the fact that the internal BEC is still going to overload trying to deliver the amps a servo's going to need. The weak link is still in there. Only other way I'm aware of for reducing the voltage after the internal BEC is to reduce battery voltage back down to 2S. Which doesn't really fix the 'how to run on 3S' thing.
