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HelicopterMain Discussion › fbl and current draw
12-27-2016 06:15 PM  10 months agoPost 1
wc_wickedclown (RIP)

rrProfessor

long beach calif

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fbl gyro draws more current than a FB helicopter

recommendations please and thank you

castle pro good bec to use? or us robotics.

on my 700 running HV servos so ran separate power wires to the lipo to supply extra power.

running us robotics bec on my 600 works great

seems like not too many pilots are up on this issue.

Insha Allah made in america

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12-27-2016 10:47 PM  10 months agoPost 2
Andy from Sandy

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Bedfordshire, UK

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I have a T-Rex 600N running Futaba BLS272 cyclics and BLS276 tail with S3072HV on the throttle. I am using a V-Bar NEO controller.

I power this with LiFe pack and charge after each flight. I don't know what the peak current is but I put back around 150mA after a 7 minute flight plus all of the starting up and walking to and from the flight line.

Futaba are known for not having huge peak current draw like some others plus don't produce massive back emf surges that upsets a lot of electronics.

I used to have a set of BLS451s and a MKS BLS980 and that set of servos drew slightly less current for a flight.

http://lygte-info.dk/review/batteri...llow)%20UK.html

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12-27-2016 11:01 PM  10 months agoPost 3
JuanRodriguez

rrProfessor

The Villages,​Florida

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Whatever link you posted does not work, at least for me....

Been there, done that and old enough to know better.....

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12-28-2016 03:47 AM  10 months agoPost 4
wc_wickedclown (RIP)

rrProfessor

long beach calif

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+1 for Futaba and I should have said E models tho yours sounds like a nice setup

Insha Allah made in america

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12-28-2016 06:03 AM  10 months agoPost 5
jhartsock3

rrApprentice

Greenwood, IN

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I run a wide range of servos high voltage and low volrage. All my birds are fbl. On hv I use straight 2s lipo. With on exception my 766 uses castle pro bec. All my lv setups use a 2s or flight pack to. supply castle pro bec. Never had a brown out do to power problem. But I have had one break the negative wire behind my ec3. It was my fault wicked up to much solder in wire. .

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12-28-2016 08:40 AM  10 months agoPost 6
Andy from Sandy

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Bedfordshire, UK

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The url closing tag ended up in the wrong place. I have fixed it now. It is a link to a test carried out on the A123 cells I use.

http://lygte-info.dk/review/batteri...llow)%20UK.html

I would expect an E machine would probably use the same current during a flight (for me at least).

Yes, thanks, the nitro is a nice helicopter although I have just had to change near enough every single bearing as they seemed quite worn.

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12-28-2016 12:15 PM  10 months agoPost 7
Andy from Sandy

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Bedfordshire, UK

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What I think has happened is some fbl programmers used the specs of the servos for the refresh rate out to them. This led to high current draw over a flight and hot servos.

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12-28-2016 02:22 PM  10 months agoPost 8
ICUR1-2

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Ottawa, Ontario

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FBL units

It all depends on what is causing the draw.
A vibration in the air frame can cause the fbl unit to work the servos more. Depending on the servo's some draw more current than others.
The fbl unit IMO doesn't draw that much current by itself.

My solution was: get good servos with low amp draw or higher torque servos
use a BEC pro or better regulator or use a separate RX pack

Anything bigger than a 450... IMO needs an external power source for the RX

Nimhs might be out of style but they still work well if all you need is 6V

spending time, paying attention

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12-28-2016 03:55 PM  10 months agoPost 9
wc_wickedclown (RIP)

rrProfessor

long beach calif

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FBL units
It all depends on what is causing the draw.
A vibration in the air frame can cause the fbl unit to work the servos more. Depending on the servo's some draw more current than others.
The fbl unit IMO doesn't draw that much current by itself.
My solution was: get good servos with low amp draw or higher torque servos
use a BEC pro or better regulator or use a separate RX pack
Anything bigger than a 450... IMO needs an external power source for the RX
Nimhs might be out of style but they still work well if all you need is 6V
high 5 brother you're still the man.

thank you

Insha Allah made in america

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12-29-2016 07:26 PM  10 months agoPost 10
coolice

rrKey Veteran

Northamptonshire,​England

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Hey buddy.

You'll find its not the servos particularly pulling current (although some do more than others), but it's the FBL controller moving the servos more than required thus increasing current demands.
The Vbar units I've proven to be very frugal on their current use in flight, this was found when proving to another flier the Align Gpro was a high current usage unit by comparison. Identical airframes and setup, except one was flying a Vbar and the other a Gpro and the peak draw was 4.xx amps for the Vbar and 14.5 amps on the Gpro.

Vibration is a cause, but it's more the FBL's internal programming not filtering out the unwanted inputs it is feeling over the ones it does need to act on. Hence the increased draw as it commands the servos more than required, thus this also generates more heat in the servo as well. It's a problem that effects multiple areas.

The BEC PRO is a good unit, but many like the simplicity of a LiFe (straight 6.6 volts nominal on 6 volt capable servos), or straight LiPo on 8 volt capable ones. Make it just a simple plug and play power setup. Ideally just add two or three servo style connectors from power source to Rx/FBL to assure current capability.

Not sure on NiMh cells with FBL, it'll work ok but this cell type can't really maintain a constant voltage as well as a LiFe or LiPo, so high stress flying will cause voltage dips. Something you don't really want when you're asking the servos to not only fly the machine but provide its stability to. That's forgetting the receiver/sat brown out voltage threshold as well at the high demand points.

Ian Contessa

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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12-29-2016 08:52 PM  10 months agoPost 11
oldfart

rrProfessor

Vancouver, Canada

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An FBL head, even when flown without FBL electronics, draws substantially more servo power then an FB system, simply because the fly bar acts like a "power assist" system. Without it, the servos are left to do all the work.

Phil

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12-29-2016 09:41 PM  10 months agoPost 12
coolice

rrKey Veteran

Northamptonshire,​England

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Hey buddy.

It's not the flybar that helps specifically, it's the various control arms and bellcranks that connect the servos to the blade grips which provide a mechanical advantage to the servos. It's a more complex setup thqt requires additional parts that help.
In reality the flybar is just there to ride the external influences on the model and give corrective inputs to the blade grips. As well as stability as a result.

The old flybar setup gives the system a mechanical advantage with the relationship between pivot point and input/output points on these arms, fulcrum comes to mind..... been years since I've used that word.

Ian

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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12-31-2016 06:40 PM  10 months agoPost 13
oldfart

rrProfessor

Vancouver, Canada

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Yes Ian, that is why for sure. I just wanted to be brief.

Phil

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HelicopterMain Discussion › fbl and current draw
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