A warning to the wise

[st200ol]

I'm just thinking out loud here really, but I wonder; if the servos are provided with more power then they may be the next item to fail in the chain. If they are constantly running at or near their max current then that can't be good for them.

Maybe what is required is some firmware optimisation on the FBL controller, reducing current to the servos a bit, can this be done without affecting the flying characteristics too much though?

[pug907]

Have a read through this
Power supply | VStabi

I posted on vstabi forum, when my E5 pranged for the umpteenth time and one of the replies mentioned he was using a life pack and having the "low voltage" error with resulting carnage.
His fix was to "piggy back" a separate lead from the ESC to Vbar, as the small gauge wires are only capable of a 2A-5A carry. All double Dutch to me, I'm ashamed to say, but it cured his problems, so who am I to argue lol. All I can say is, after 8 minutes flight and over £350 damage, I really don't need it happening again . Why are the manufacturers not beefing output wires up, to avoid the issues? What use is a 150A(LV) ESC that can't run 3 standard servos? Lets face it FBL has been around for long enough to have highlighted issues, surely??

I just hope someone reads this entire thread , before putting their "ill equipped" pride and joy in the air, like I did (4 times, duuuhhhhh).
Cheers.

[swale]

This is all why I started useing hv2bec nice beefy wires (big as u can get in servo plug) 50amp continuous current no servo gonna stall my bec and fbl :-D

[Tim Procter]

This is all why I started useing hv2bec nice beefy wires (big as u can get in servo plug) 50amp continuous current no servo gonna stall my bec and fbl :-D

Seen that Reg that you have Swale and its certainly a great unit.

I was using a Western Robotics Super BEC with a 15A (Max) Peak and it was stalling the HV servo's when wrenching the sticks causing a brown out.

Have changed to a Gryphon Quasar 10A (Cont) and 20A (Max) Peak and it handles them with ease with no stalling the servos or brown outs.

The one thing on your helis you cannot skimp on is the power actual supplied to it.

[pgkevet]

At the overprice of good regs I'd be inclined to go LiFe direct with dual redundant switches on a nitro to save canopy removal or direct plug on a leccy where you have to take the darned thing off anyway. But that's all part of my 'pigged off with silly prices' policy....

[AliHumphrey]

I run a Gryphon Extreme-Heli Voltage Reg on my T-Rex 700E DFC and power my T-Rex 700N directly off a 2S 3650 mAh Opti pack. I have MKS HV brushless servos on both.

[KevDavies]

I'm just thinking out loud here really, but I wonder; if the servos are provided with more power then they may be the next item to fail in the chain. If they are constantly running at or near their max current then that can't be good for them.

Maybe what is required is some firmware optimisation on the FBL controller, reducing current to the servos a bit, can this be done without affecting the flying characteristics too much though?

Therye not getting 25 amps shoved up their arse tho!! It means thats what is available should they need it!! Years ago I did a test on a BLS451 and it was drawing 8 amps (peak) on its own in the steering on a 1/8th buggy. If the power is available to the servos they will not stall! If they cannot draw enough current to prevent a stall, they feedback into the loop and cause brown outs and all sorts of wierd shit!

[Rainman]

Don't forget that the standard JR/ Futaba connectors are also a current limiting factor !

Richard

[Rctintin]

Align HV servos have been tested to show a peak of 13A current draw each, but this is only for .03 second. So with top pilots like Swale banging the sticks around, 4 servos can pull around 50Amps!!

I have seen Jamie Cole spank the tar out of his 700e weekend after weekend with no issues at all because he uses a Scott Grey Reactor HVX reg. This reg is 25+Amps continuous output, and has been tested to 75Amps peak draw. The big advantage is the Rx lipo is a 3s, so even when it's getting low on power near the end of its charge, the reg will still supply upto 8.4v at full power.

I have one on my 700dfc pro, and it has been faultless powered from an Opti 1300mah 3s lipo.

[trillian]

The big advantage is the Rx lipo is a 3s, so even when it's getting low on power near the end of its charge, the reg will still supply upto 8.4v at full power.

I have one on my 700dfc pro, and it has been faultless powered from an Opti 1300mah 3s lipo.

I've been wondering for some time why all these higher end regs were not using 3s LiPos for that exact reason, that when you start with 12 volts you have a lot more room to play with and the reg can keep delivering its target voltage.

[KevDavies]

I have that same reg on my Goblin now, but on 2s. But as im running my tail servo at 5.2 and cyclics at 6.6v I cant see it being a problem. If I was to run above 6.6 tho id use a 3s

[600srad]

Ahh thanks for the heads up people, been waiting to co.vert my 600n to dfc, but after power probs on a 450 have been putiing this off.
Ian.

[cjcj1949]

Good to see some measuring going on. You can now get super capacitors in the Farad range that would be a way of handling peaks. Separate power supplies for each servo is the way that MKS recommend. That gives smaller linear BECs that protect the servos better and keep the voltage dips from high current away from the electronics that will reboot through low volts. Low volts on a servo due to a current peak will be noticeable in performance, but probably not fatal (Ithink).

[steve_b]

I've been using the Gryphon extreme regulator for the last couple of years on my helis without any issues. I did consider the BEC route but preferred this as you plug the battery and servos into the regulator, so you're not using the Rx to distribute the power and ultimately the small servo wires and connections, which will end up being the limiting factor.

[cjcj1949]

Hopefully it separates the supplies as well. The main thing is it works and shows some design sense.

http://www.align-trex.co.uk/gryphon-...gvr-7020s.html

That's a linear design that works off a maximum voltage of 10V. (2S Lipo or LiFe). Expensive for small helis, but for larger ones it only needs to prevent one crash.