New Hurri pilot - Powering the RX

[Luciora]

Hey guys, got my 2nd hand Hurri this afternoon (upgrading from a Mini titan), now I've got a few questions about powering the RX.

Quite a few people are running their setups with a 2nd LiPo that runs the RX instead of running off of the usual main LiPo.

What is the advantage to this? How would you set this up?

I've got cyclic servos running on DS821's (think they are the ones you get with the DX7 package) and tail servo is a Futaba S9257.

I've installed a 60A Hobbywing ESC (built in BEC) however this is 6v and the tail servo is rater to 4.8v. The kit came with a 50A GAUI ESC and aftermarket BEC soldered on to it to reduce voltage to 5v.

What would be best setup to get it all running? Do I move the BEC to the 60A ESC and follow Finless's trick to get it all working on a 6channel RX? Or do I look into the 2nd battery to feed power to the RX?

[mysticmead]

you can do it either way. of course, running the servos off the main packs can reduce your flight time a little bit. plus having a separate pack would make it easier to power the servos and set your curves without having power to the motor..

[michael88997]

yea i run a separate pack just because you can get a little more time and i figured the big packs already have enough strain on them and a 1000mah pack is very light so weight isn't a issue...

[Luciora]

Found the manual on their website now.

Mentions in there that optimal is the 2nd pack to power the RX, it just connects via BEC to the Battery port on the RX. Is this correct?

How does it influence the ESC powering the system via the Throttle connector on the RX?

Do you just run a normal 5v BEC to the RX then?

BTW I'm running Spectrum 6200 RX.

[skigolfmike]

How you power the RX and servos depends a lot on which servos you are using. A BEC off a 2S RX lipo running at 5.1V is probably fine with the servos you are using. If you want the cyclic servos to be faster, use 6V to the receiver and put another step down between the gyro and the receiver.

The other reason for not running a BEC off the main batts that the rated output of the BEC drops the higher the input voltage. Most external BECs are switching power supplies, which are more efficient (make less heat) then a linear voltage regulator. There is a limit to what a switching power supply can handle though. For example, with a CCBec on 6S it's 3A and I believe the CCBec can handle 10A on 2S.

I setup an 8V system on my 550. I have a 1380mAh 2S running the receiver and the cyclic servos. I have a Spektrum stepdown to 5.2V for the gyro and TR servo. My receiver, servos and gyro electrics pull close to 3A at idle.

[Luciora]

Just one last question, when connecting the ESC to the RX, do I need to remove the red wire from the connector going to the Throttle on the RX to stop it from feeding power to the RX since this will be done via the Battery input?

Or is the RX smart enough to detect input on battery as well and not use the power coming from the ESC (built in BEC) ?

[phunk]

Disconnect the red wire from the esc if you're using a separate receiver battery.

[Luciora]

Many thanks all, got a little 2cell lipo running the RX and all seems to be happy. Slight wobble on spin up but that could be the shaft since it isn't new.

Now just to set the tail up and get used to this HUGE thing :p Oh and off to find throttle curves...

EDIT- Ok just took her out for a quick test flight. All seems quite happy except I get a "hiccup" every now and then where it is almost like the motor is losing power for a split second then goes back to being fine. No idea what that could be.