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Power choices! Which way to go?

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Dogman:
I am a newbie(just one year in helicopters and r/c equipment), and power options seems to be a hot always talked about subject. I have not seen a definitive route that people go by, I think causing HUGE confusion, and I believe crashes are happening due to this topic. I would like to see some professional answers with hard documented statistics.
I am confused by the setups people are using with flight packs, separate power for electronics, and back up guards. On my 550x it is a 6s system where I am running a 6s 5200mah flight battery, with a cc BEC pro hooked up to a 2s 1350mah to power the Rx and servos. The servos I run on the 550 are savox cyclic and tail. They are not HV servos so I have the BEC regulating @6.0V. That is way below the nominal output of the 2s lipo @7.4V, so the step down gives me at least 2 to 3 flights before I need to charge the Rx pack. In that setup I know I always have steady power to the servos. Both birds are using a AR7210 BeastX.
Now into my new Synergy E7SE. Its a 12s system. It uses 2 flight batteries 2x(6s 5200mah), and has all true HV cyclics and tail rated at 8.2V for tail and 8.4V for cyclics. Now if I run the same mannor where the Rx is direct to the 2s battery, it is physically impossible to utilize the true potential of torque and speed with that setup due to the nominal discharge of a 2s lipo. With the 550 not an issue from the BEC step down, but with this E7, I want to use the servos or why even waste the money on HV's? If I have to charge the Rx pack EVERY flight just to have HV for 1 minute or less, sorry but I see that as a complete waste of money. People will say if you run the servos at their HV potential, they won't last long? That seems again not smart. Why would a servo company make a product that you can't use to full potential? It makes good sense to me(but I was shot down with this idea) on a heli that has HV servos to run a 3s 11.1V battery to power electronics through a BEC to step it down to maintain 8.2V so I always have constant even power to servos, and can utilize their full potential. I think that people are crashing helis from direct hooking to a 2s lipo, then getting brown out due to inadequate voltages where then one or more servos brown out causing a crash, and how are you going to tell what caused it when you have a pile of carbon fiber in front of you? I don't like the idea of hooking BEC up to one of the flight packs due to....what happens if you burn up the esc, which shorts out flight batteries? I thought that's why we put in separate power for electronics, to eliminate the possibility of not being able to auto in with no flight power. I understand also about the scorpion back up, and I have one and plan to install for the third method of a backup power supply in case the Rx power craps out. I am not a sponsored pilot, so I can't afford to be digging holes with my E7. Maybe if Synergy would sponsor me, this would not be a subject for discussion...lol. Please will someone chime in and help get to the bottom of this always forgotten and never resolved power issue. We are so focused on servo stats, that we overlook the servos are not running at HV numbers where unless you have telemetry, you would never know what voltages your RX and servos are running on, and flying 3D, I don't have time to take my eyes off the bird to check voltage numbers.

cml001:
Hi Dog, welcome to Synergy! Are you having issues? While I'm not the guy for tossing numbers & statistics.. I'll tell ya what I think.
First off the BEC. When I started in the hobby there seemed to be constant discussions/post bout BEC failures from just about all the manufacturers. Now at that time my experience stopped at 450 class.. in which I used an internal BEC in the ESC.. so upon building my 1st big bird I opted for an RX pack. Somewhat the same situation as u discribe, it wasn't a HV set up so a regulator was needed. Worked fine. Almost all setups since have been HV using a 3600mah RX pack.. no BEC & no back ups. This allows for at least 5-6 flights and I've never noticed a change in performance.. keeping the 20% rule of course. I personally have never had brown outs in the manner u describe from n RX pack. Having said all that, most of the guys I fly with do use a BEC and I have put one on my last build.. almost a year into this one and no issues with the BEC PRO only.
Product quality also plays a huge roll. While every manufacture may have a hiccup or a poor product on occation.. do they stand by it & improve upon it or just keep pumping them out? Customer service/support are huge to me personally. But if the product is feared of failing such that u have to get a backup.. I don't want it.. never a fan of backup guards. if I don't trust the BEC, use the RX. I think more equipment means more potential for failure. 
As I said.. I'm not a numbers guy..  preflight check, plugged in, lets fly! Lol. There are a bunch of guys here who love the numbers and I'm sure they will chim in. Pick a good quality product, I like Castle.. install properly.. have fun with it. There are now some great products for the bigger birds with internal BECs as well.. the Castle Talon 120 is a popular choice for the E7, may wanna have a look at that.

Dogman:
Thanks for the help, I believe in short you kinda agree with me that it is a good idea to run a BEC, set to whatever you feel comfortable pumping through the servos(larger birds need the high torque and high speeds to really fly nice) , and then just have some fun. So for my E7, what is the best power for the Rx being a Ar7210, being able to handle 8.5V, and running a CC BEC pro, with HV servos all able to handle 8.2, with a Phoenix Ice 2 HV160? I was thinking to get a 3s to be able to maintain in that 8.2 range for a few flights? In my head the 2s would not be able to maintain the 8.2 even for the first flight or even 8.0V for the first flight. Shoot, I'd bet by the time you hook up all the batteries, get the canopy on, do a quick pre flight check on linkage movement, if you had a 2s you would already be below or right at the 8.0V mark where then its just down to 7.4V real fast, and now way less torque. Just trying to clear whats clogging up my brain, lol.

cml001:
On my E7SE...HV set up.. using only a 2s 3600mah RX pack.. no BEC needed. U are not going to see a decline in performance as long as u obey the 20% rule. I personally would choose either the BEC PRO or the 2s pack, not both. I would definitely not recommend using a BEC & a 3s pack.. using the 5200mah 12s is already making u heavy.. I'd try to keep it light as possible.

Dogman:
On hand I have a Pulse 2s 2550mah receiver pack. Is that safe for 2 flights with the 700? Hooked up directly, no BEC. The weather is going to be warm enough to test out the E7 at the end of week here. I would like to see this awesome machine fly. If there wasn't 6" of snow on the ground and 20 degrees, I'd be flying.

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