CC BEC Pro or 2S Lipo

[semperfib400]

I'm currently building my 700L and am considering using the castle creations BEC pro since you can regulate the voltage to exactly to 8.4 volts. My question is, is it safe/more reliable to run a 2S lipo however? Seems to me using the CC BEC would save a little space as well.

What are your thoughts?

[KSHeli]

With HV servos just go straight 2s lipo that way you have fewer points of failure. You'll get more power out of your servos with the continuous 8.4 V if you fly that hard, but not many of us need that.

[K2Freak]

2s lipo is not less points of failure, it's more. Lose a cell in the rx pack and watch the fun. I like a high quality bec much more than an Rx pack. Less moving parts and less charging / monitoring.

I may be biased, as I lost a scale plane to Rx pack one time, but bec still has 100% track record for me. I have recently added a few grams of scorpion backup to assuage the risk of possible trouble...

There are many drawn out discussions on this topic. Do a search and you will see that it's a little bit of a religious battle.

[KSHeli]

Originally Posted by K2Freak

2s lipo is not less points of failure, it's more. Lose a cell in the rx pack and watch the fun. I like a high quality bec much more than an Rx pack. Less moving parts and less charging / monitoring.

I may be biased, as I lost a scale plane to Rx pack one time, but bec still has 100% track record for me. I have recently added a few grams of scorpion backup to assuage the risk of possible trouble...

There are many drawn out discussions on this topic. Do a search and you will see that it's a little bit of a religious battle.

Scorpion is not rated for uses on an hv setup though, but he could use the Optipower backup device.
I've had to crashes due to bec failures, granted it's been awhile back.
Just saying nothing is 100%, it's electrical.

[K2Freak]

Yes, I like the looks of the Optipower too. I'd definitely buy that over the Scorpion today.

If money was no object (>$300 per heli) I'd buy the BEC, J log, power bus, and buffer pack from these guys:

http://www.r2prototyping.ch/?page_id=709

http://www.demonaero.com/product_p/r2-hv2-bec-al.htm

[reich2004]

I've had good luck with my BEC's. I run the CC pro on my 700L and 550L. No issues with either. The Align servo's are crazy efficient, so they don't draw much amperage to really push a BEC anyway. That being said many prefer WR BEC's. Personally, I like the programming of the CC BEC and generally like Castle all around. Just make sure you wire it for 6S if you go that route.

[Ah Clem]

I have to agree with K2Freak here:

"2s lipo is not less points of failure, it's more. Lose a cell in the rx pack and watch the fun. I like a high quality bec much more than an Rx pack. Less moving parts and less charging / monitoring."

I lost a cell in a 6S pack a couple of weeks ago. With five cells powering the BEC, I had no problems (other than sagging power to the motor).

If it had been a 2S pack, I would be rebuilding right now...

I have WR BEC's in all of my large machines (please note my signature, below).

[vtown nick]

Bec pro working great on my 700 and goblin 500 with bk servos. I just got the optipower backup for the 700 so it will be that much more reliable. It's nice to just plug a flight pack in and go, another key point no one has mentioned is that's just another lipo to maintain and charge in order to fly the machine if you go rx pack.

[K2Freak]

Wrong thread...

[atkin]

I run a Gryphon BEC on the HV servos on my 700. But I find this interesting:

http://www.vstabi.info/en/node/1327

[Russell Harding]

There is risk/benefit to each.

Personally I use a 2S lipo. It is 3000 mah and good for about 10 flights. I charge it every now and again. There are few parts to fail and the current output is unquestionable.

However, failing to charge it WILL result in a dangerous crash. I have voltage telemetry. I would not leave an unpowered Rx up to human error (charging the Rx lipo) to chance.

Personally I think 2S is the way to go, but only with telemetry alarms to prevent flying with a low battery.


Sent from my iPhone using Tapatalk

[rhodesengr]

I got used to using 2S LiFe on my gassers. If you think about RC history before electric power became popular, everyone used a RX battery for everything. I don't know about counting failure points though. It seems the same. Either the BEC or the RX battery could fail. However, you can also fail your main pack or run it down too far in which case the BEC also goes out while an RX pack maintains control power.

I think of it as a redundancy. With a BEC, everything runs off the main packs. With an RX pack, control power is separate from motor power.

It boils down to personal preference and then after that luck. BEC's have failed. Main packs have failed, RX packs have failed. I don't think anyone has enough data to say which setup has a lower failure rate.

[Ah Clem]

We used to use 4S Nicad (later, Nimh) packs for the receiver.

If you lost a cell, you were done.

When I started flying nitro again about 8 years ago, I used 2S, 2P packs. These packs would still work if you lost a cell.

If you run a BEC from one of the batteries powering the motor, you can lose a cell (or two, or three) and still have enough voltage to get the machine down (most BEC's will work with three cells).

Lose a cell on a 2S pack, and you are done.

With receiver packs, you should check the voltage under load, prior to every flight. You also have to charge, check and, maintain the packs. (When I fly nitro machines these days, I still do this).

With a BEC on an electric powered machine, you have a fully charged flight battery, ever time you take off.

[ah_liang]

I run a 3s pack to the cc bec pro and drop it to 8.4V. I feel more comfortable with this arrangement becos a 2s pack will have its voltage drop over usage and therefore not maintain 8.4V throughout. The only BEC I run 14s with is WR Super BEC.

[jhamel]

I use the CC BEC Pro exclusively on all my 550 to 700 size helicopters. On the 12S setups, I power the BEC Pro with the first 6S pack of the series. I have the BEC Pro's set to 7.5v on all HV setups. The folks I've talk to claim that running the BEC higher than 7.5v just makes the servos run hotter without any significant improvement in performance.

I used a WR Super BEC in the past. No performance issues. However, there were a few things I did not like. The WR Super BEC wires are much stiffer than those of the BEC Pro, so it may pose a challenge to run the wires neatly in some setups. Also, unlike the CC BEC that allow for very flexible output voltage programing, the WR Super BEC is limited to four voltage options. One of the four voltage options is 5.2v, which is virtually useless for our application. A third issue is that the WR Super BEC may interfere with the Spektrum telemetry signal. Not a big deal if you are not using Spektrum telemetry, but something to consider if you are.

[Dawiev]

No, you cannot set it to exactly 8.4v . The granularity of the voltage selection on the CC BEC Pro lessen the higher you go - 7.0, 7.5, 8.0, 8.5v.

I've not seen a single servo rated at 7.5v, or at 8.5v. It is either 7.4v, or 8.4v ? Easy to set at the value below for safety, but then you're sacrificing speed and torque.

Doesn't make any sense to have 0.1 increments for 5v setups - who uses a CC BEC Pro on setups requiring 5.7, or 5.9v ? Surely it should be simple to provide an HV firmware version that gives the granularity in the 7v and 8v range !

[jhamel]

Originally Posted by Dawiev

Easy to set at the value below for safety, but then you're sacrificing speed and torque.

I researched this topic recently. I corresponded with Clint Akins (Castle Creations), Thomas (MKS servos), and Lance (BK Designs LLC). I also corresponded via PM with more experienced pilots, and have reviewed other HF threads on this topic. I believe there was also a recent podcast (name of podcast cannot be mentioned in HeliFreak) that briefly discussed this point. The consensus seems to be that powering HV servos higher than 7.5v makes the servos run hotter without significant improvement in perceived performance.

[Dawiev]

If the servo is rated for 7.4v, do you run it at 7.0v or 7.5v ?


Ps. Not trying to be difficult. Trying to learn please.

[ranchhand]

I'm going to run an optigaurd, through a Y harness so I don't have to plug and unplug it to the data port on my HC3sX. It's an HV setup, 2s lipo, what gage wire should the Y harness be made of?

[jhamel]

Originally Posted by Dawiev

If the servo is rated for 7.4v, do you run it at 7.0v or 7.5v ?

If it is an HV servo, unless stated otherwise it should handle the 8.4v of a fully charged 2S LiPo battery. The servo specs may rate the speed and torque at 7.4V, but it does not necessarily mean that that is the maximum voltage it can safely handle.

Assuming that you are dealing with an HV servo that can safely handle the 8.4V of a fully charged 2S LiPo, I would set the BEC to 7.5V.