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HelicopterScale Model RC Helicopters › Using a BEC for receiver in scale?
12-17-2015 12:55 AM  20 months agoPost 1
1drummer

Senior Heliman

Brookhaven, MS USA

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I have been in and around scale for a while now and I am trying to catch up on the current technology and philosophy's of my all of my mentors out there. I have always flown my electric helicopters with my lipo's and a dedicated receiver battery.
My question is, there are some folks that fly their helis with BEC's, supplying power to the receiver and servo's, but it doesn't seem like a common thing with the folks I have been around and many are here. Therefore, I'm sure there is a good reason why that practice is not the norm. What would be the reason that this would not be a good idea or would that be acceptable, but with certain things in mind??

Thanks

Richard

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12-17-2015 01:01 AM  20 months agoPost 2
Copter Doctor

rrProfessor

Enterprise/ft.rucker ,al- home of army aviation

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Not me, I use a separate receiver battery. I am old school and with nitro power I have always used a separate battery for the rx. with electrics, its still the same for me. I have seen battery packs go south that caused loss of power to the motor but thanks to the separate battery for the receiver, control was not lost.
I have also seen the same happen with the one battery that powers everything and the results were not good for the model, the folks who had to run for dear life, nor the car it slammed into.
I say use that separate pack for the rx.

drive a rotary, fly a rotorcraft

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12-17-2015 01:44 AM  20 months agoPost 3
ssmith512

Key Veteran

Indianapolis, IN USA

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I too have always used a separate battery. I like being able to power up the control electronics and testing them and allowing the FBL system to initialize prior to plugging the main motor battery packs.

Steve

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12-17-2015 01:48 AM  20 months agoPost 4
doorman

rrProfessor

Sherwood, Arkansas

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Separte Battery

I also always use a separate battery for my rx and sx.. I still use a BEC with it though... I usually use a 2 or 3 cell lipo for the airborne electronics...motor batteries are separate..
On my latest heli (H-34) I do not use a BEC... I am running all HV equipment so that I can just use a 2 cell lipo direct to the rx and sx.. I am liking the HV set up...

Welcome to the scale side of this great hobby...

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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12-17-2015 01:54 AM  20 months agoPost 5
flyawayed

Veteran

orlando , fl .USA

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I 3rd that having a reciever battery with ur power batteries is the safest way to fly. Anything bigger then a 450i always use a separate power source to keep from losing ur aircraft incase the ESC were to ever give problems ie( burn up) and fell.

edward lopez sanchez

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12-17-2015 02:10 AM  20 months agoPost 6
coptercptn

Elite Veteran

Mesa AZ. USA

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Same here, I power all electronics w/2 cell life batts and on the bigger ones use a redundant 2x2 battery set-up...all @ 6.6v

Home of the "Sea Cobra".....

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12-17-2015 03:15 AM  20 months agoPost 7
Keygrigger

Veteran

Mississauga, Ont. Canada

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My scale helicopters have always used a separate receiver/electronics battery and BEC. Even when I ran pod and boom with large helicopters, I had a separate battery and BEC. For smaller helicopters, I run a BEC off the main battery pack for 6s and smaller systems.

Don

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12-17-2015 12:30 PM  20 months agoPost 8
Thumper217

Senior Heliman

Slidell, LA - USA

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OK I'll buck the trend here but just a little bit...on my first two scale helis both 600 size I used a Castle BEC and powered everything off the flight batteries. I built them both about four years ago and I still enjoy flying them both today.

That being said I now use a separate battery for my electronics for the same reasons everyone else has stated. But I just wanted to say that I have had success using a BEC off the flight batteries to power everything but I also don't use my older batteries on them.

AM

Thumper

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12-17-2015 02:28 PM  20 months agoPost 9
BarracudaHockey

rrMaster

Jacksonville FL

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I lost my beloved 2 meter Red Bull Porter PC-6 to not having a separate receiver battery when the flight battery failed.

Everything gets either a separate receiver battery or an Optipower backup guard now.

Andy
AMA 77227
http://www.jaxrc.com

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12-17-2015 03:46 PM  20 months agoPost 10
DFC

Heliman

Colchester UK

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My experience is mixed. My first scale model was an align Hughes 500 (MD500) using TREX 500 mechanics and an Align four bladed rotor head. Initially I powered the RX and servos from the BEC built into the Castle 70 ESC. Everything worked very well and I did a lot of experiments using the Castle data logger. However, when I tidied the wiring up the model suddenly became unstable immediately it left the ground and turned on its side and crashed (several times). In the process of doing repairs I tried changing the RX, the 3-axis SAS, the servos etc, all to no avail and in the end put in a separate 3 cell battery with a BEC and all has been well since but still using that same ESC.

My second scale model was another Align Hughes 500 with a five bladed head and converted to NOTAR for experiments. (See my posting under MD500 NOTAR). Here I've been using another Castle 70 ESC using its built in BEC to power the RX etc. I tried converting to a separate battery pack and BEC for the RX but the extra weight put my NOTAR system at its limit and I've converted back to the built in Castle BEC with no problems. Weight seems to be critical with NOTAR if you want to retain tail rotor effectiveness!

One last point. I took the cover off the first Castle ESC and thought I could see some tracking between two of the connections to the RX lead. Didn't take it up with Castle - they're too far away! But to repeat my second ESC with its BEC has been fine.

Don

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12-17-2015 06:46 PM  20 months agoPost 11
1drummer

Senior Heliman

Brookhaven, MS USA

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Thanks guys for all of the feedback AND it makes PERFECT sense.
I will continue to follow all of your leads, I just had to ask the question. I will continue to use separate batteries...
So the use of a voltage regulator to reduce a battery voltage down to 5 volts is a good practice? I have always used 4.8/5000mah packs to this point to drive my receivers over the years....

Thanks

Richard

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12-17-2015 06:50 PM  20 months agoPost 12
1drummer

Senior Heliman

Brookhaven, MS USA

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What setup should I use to regulate my battery to receiver / servos?

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12-17-2015 07:57 PM  20 months agoPost 13
ssmith512

Key Veteran

Indianapolis, IN USA

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Several options available all depending on your servo capabilities.

I prefer a "high voltage" setup. There are a plethora of servo choices available now that can handle 8.4 volts. This is considered a "high voltage" setup. A high voltage setup is simply a 2S (2 cell) LiPo battery plugged directly into the RX.

Or, a lot of folks like using a 2S LiFe (also known as A123 batteries) battery plugged directly into the RX. This gives you roughly +6.6V. LiFe batteries are more tolerant than LiPo's at being left charged. However the voltage drop off of LiFe batteries is VERY quick.

Others will run a 2S or 3S LiPo or Life into a voltage regulator (or BEC) to drop the voltage feeding the RX to whatever you want - i.e. 5V or 6V or 7.4V, etc. The thing to pay attention to with using a voltage regulator (or BEC) is the amp output rating. Servos nowadays are pretty power hungry so a powerful and robust volt reg or BEC is an absolute must - Western Robotics, Castle, and Perfect Regulators are few that I am familiar with that could be recommended.

My 700 size electric Cobra uses a single 3600mAh 2S Lipo plugged directly into the RX pack. My 1/5th scale turbine powered Airwolf uses 2ea 3600mAh 2S Lipo's running into a PowerBox regulator supplying the RX with 7.4V. the 2 batteries are for redundancy of course. My 700 size electric MB-105 will use a single 2500mAh 2S Lipo plugged directly into the RX.

Hope this helps!

Steve

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12-17-2015 08:17 PM  20 months agoPost 14
doorman

rrProfessor

Sherwood, Arkansas

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2.4 and 4.8 Volts

Hi Richard,

Just so you know, the new 2.4 systems and digital servos is NOT a good mix for 4.8 volt batteries any longer.. under load, that 4.8 can drop off to less then what the rx needs to operate, and create what is called a brown out... which means your system shuts down.. NOT GOOD...
I think Steve has covered just about all the info that you would need to use a regulator ore BEC, or HV.. I am currently moving all of my machines to HV, just to simplify the wiring....

Good Luck, Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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12-17-2015 08:40 PM  20 months agoPost 15
1drummer

Senior Heliman

Brookhaven, MS USA

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Thanks Steve, Stan,

Yea that's why I am throwing the questions out, to keep me from that possible situation and I appreciate the feedback for sure.
I am just trying to upgrade the battery power system for now, then work on HV as I move forward. Right now, all of my ships are the 4.8 type of receivers and servos.
I like the LIFE battery idea, but I will have to reduce voltage with ??

Thanks

Richard

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12-17-2015 08:45 PM  20 months agoPost 16
ssmith512

Key Veteran

Indianapolis, IN USA

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What size heli? What servos will you be using for collective/cyclic?

Steve

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12-17-2015 09:09 PM  20 months agoPost 17
doorman

rrProfessor

Sherwood, Arkansas

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LiFe's

If you choose the LiFe type batteries, I would suggest that you step the 6.6 down to 5.8 max.. Most servos can handle this voltage unless they specify 4.8 ONLY...your rx will handle it with no problems..
If by chance your are running a gyro and tail servo, I would step that down to 4.8v. (called Old School!!!)

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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12-17-2015 10:17 PM  20 months agoPost 18
1drummer

Senior Heliman

Brookhaven, MS USA

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I fly Vario with futaba 9206 servos, 401 gyro.
Thanks Stan

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12-18-2015 08:40 AM  20 months agoPost 19
Andy01

Senior Heliman

Brisbane, Australia

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I run a pair of 2s A123 (same tech as LiFe) batteries into my JR PowerSafe (dual power input) Rxs with no regulators or BECs. It works just fine for any (decent?) servo rated for 6V.

I use Futaba BLS252 for all 3 heli's cyclic, and 451 for the tail on two - all direct off the 2s A123. I have a BLS254 on my Long Ranger which has a simple Align step down before it.

The 2s A123/LiFe generally runs around 6.3-6.4V most of the time, which seems to be well within the range for many (most ?) 6V servos.

I do use the CC Ice 75 BEC on my little 500 sized UH-1N, and it has been fine, but I would not use a BEC for a 600 or larger.

You do have to be careful with A123/LiFe because the voltage falls over the edge VERY quickly. The voltage drops very slowly, and when they are flat - they are FLAT. Using the voltage or even mAh is not a great indicator of state of charge on these batteries, so best to fully charge them before every outing. I use one in my 11X as well, and have changed the Tx alarm from 9.0V to 9.5V.

Colin

Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )

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