On why BEC specs are utter bollocks
When dealing with servos consuming lots of current, the BEC built into the ESC struggles. In part it's because the BECs are rated optimistically by manufacturers (e.g. under ideal conditions for cooling seldom, if ever, seen in the real world). So when it's hotter than in the lab, especially without the 5mph cooling breeze with which they're rated (read the specs, they tell you), the current output goes down. Way down.
On current flow and how many amps the connector can actually handle
The other thing is, the connector on the BEC throttle lead is rated at 3.5A - so regardless of how much current the BEC can output (and some claim 10A, or more), in the real world, the limit is what that connector to the receiver permits, not the claim by the speed control manufacturer. Opinion? Nope, physics! So 3.5A and then it begins building up heat. Fortunately, there are ways around this problem. Want to learn more, review this article: How many amps can the servo-type connector handle?
How to deal with receivers incapable of handling HV servos at full rated voltage
So what do you do when when you're dealing with a receiver that won't handle high voltage? The solution is actually quite easy. Want to learn how to do it the right way? Just review this article titled:How to use a HV servo with a 6V-radio
BEC versus dedicated battery pack
Another method involves forking over for a pricey high power BEC equipped with two power leads (and we offer them if you're interested). These are the CC BEC 2.0 and the CC BEC 2.0 WP (water proof version). But in our opinion, the ideal solution involves just using an inexpensive 2S battery pack instead. Yup, treat your electric powered model as if it were powered by an engine.
Once you commit to powering the electronics with a 2S pack instead of a BEC you're basically treating treating the control electronics system like one used in a nitro/gasser powered model. This also totally isolates propulsion-electronics from control-electronics.
Your benefit in this is your delicate receiver and servos won't ever again see voltage spikes or back-EMF coming from the propulsion motor, which is better because they're not designed for that. Note, all ProModeler packs from 650mAh-6000mAh come with three leads, two of the ordinary DuPont type plus one XT30 (rated at 30A).
The reason for two JR-type leads (another word for DuPont connector) is since each is rated at 3.5A, then using a pair means getting 7A of power to the receiver - without heat. Other manufacturers offer packs built with two leads, also, so it won't hurt our feeling if you buy battery packs from someone else. Want to learn more? Review this article titled: Why's my pack got two JR-connectors?
Connecting two power-leads to the receiver
As for hooking the two lead pack up? It's easy! Just remove the (+) wire from the ESC's throttle lead (usually either red or orange) and that disables the power coming from the BEC circuit to the receiver. Next, connect the two battery leads to the receiver (each through a switch) and Bob's your uncle (means you're in business). The major safety benefit is now when you connect the propulsion batteries, there's no spark and without a signal from the receiver, the propulsion motor won't inadvertently come on. So now, when you're fully ready, just turn on the receiver switch and listen for the beeps from the ESC as it arms.
So how do you actually connect two leads to the receiver? That's easy too. Remember, the point of two leads is this allows the receiver to draw up to 7A (recall the limit is the DuPont connector itself, which is rated at 3.5A). By using two leads (e.g. two plus) the whole thing can draw 7A (3.5A+3.5A). Little known fact, packs with two leads were our very first product at ProModeler - this back in 1984 although at the time, the reason had nothing to do with exceeding 3.5A but for the redundancy of two switches (means odds of both failing at the same time are astronomical so crashing due to switch failure is near zero).
On using two power leads
Anyway, to make it easy to power up the system if you don't want to use a pair of on/off switches is to just add two short extensions to the receiver. Plug one into the BAT-port. Plug the other at any free channel on the receiver (channel 9 is a favorite as it's furthest from the BAT-port so if heat does build, it's not localized).
Note; if you don't have a spare channel, use a Y-harness, which we also have on the site. Connect it to, for example, channel 6 where a servo is using the channel Remove the servo and connect the Y-harness, then plug in the servo and a battery lead. Easy peasy!
Switches and the benefits of doing without
While I use switches with models where access isn't easy, if access to the battery extension leads is easy, then no switch is better than any switch ever made. Yup, you become the switch! So now when you connect the battery, you do it conveniently at the extensions instead of poking around at the receiver. Extensions ranging from 4-12" long work fine. How long? It depends!