Help - Combining multirotor, gimbal and FPV transmitter to use the same 4S battery

N

NYDave

Member
Greetings all,

I've added a new Tarrot T-2D brushless gimbal to my DJI F550. Until recently my previous servo gimbal was powered via a 5V BEC off the main distribution board. The heavier weight of the Tarrot over my light servo gimbal has lowered my flight time from 12 minutes to 8. Mainly due to the Tarrot itself and the addition of a 3S lipo to power it.

My F550 has stock motors, DJI WKM and is powered by a Hyperion 4S 14.8V 5400 mAh 35c Lipo.

I'd like to add my Gaui GV100TX FPV Transmitter to the F550. It also requires a separate 3S lipo to power it and will add further weight to the F550 lowering flight time further.

Tarrot recommend a 3S lipo with an output between 7.2v and 9v
Gaui recommend a 3S lipo with an output of 11.1v

The 3S Lipo that I have seems to be fine with both devices (3S 11.1v 1000mAh 11Wh 20c). Worse case scenario, I can fit a small distribution board and power both devices off the one 3S.

Here's my query:

Can I remove the need for the 3S add a separate distribution board off the main F550 distribution board and power everything off of the F550's 4S Lipo?
Is there any benefit to this or will the subsequent load on the 4S drastically reduce my flight time further? (I think I know the answer to this one but please humour me, I'm trying to swap the weight of the additional 3S for the weight of the FPV transmitter and retain a flight time of around 8 mins. More if possible).

In the pursuit of this idea I've looked at adding Castle Creations BEC to the supply from the 4S to the gimbal and dialing down the output to Tarrots recommendations:

http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=53_55_290&products_id=954

I've also looked at adding an inline filter to the supply to the Gaui FPV transmitter to clean up any DC dirt that might cause interference in the signal:

http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_15&products_id=138

Is there a danger I could blow the FPV transmitter without another BEC in place to lower 14.8 down to 11.1v ? If so any ideas where I could get one in the US? The BEC's I've seen only seem to put out a maximum of 9v.

Please let me know if this isn't the sort of query that belongs in this topic/thread. I've hunted the forum and can't find anything that matches specifically with what I'm looking to do.

Any advice or input appreciated.
 


S

Silverburn

Member
Just get a 12V BEC, and 3 small ferrites. 1 inbound on the cables to the BEC itself, 1 each on the outbounds. Solder 2 outputs from the BEC - one for the FPV tx, and one for the gimbal. A filter on the FPV tx would be good too, as you state.

Solder the BEC to the PDB of the F550.

I use the Gryphon Polaris: http://www.gryphon-mall.com/product.php?id_product=87. Expensive, but clean signal out the box. But you can never have too many ferrites.:nevreness:

PS - Tarrot say it needs a 3S, but then state 7.2-9V? That's not 3S...that's more like 2S. If Tarrot are using the Martinez controller board, then 3S/11.1V is best, which is why I recommend a single 12V BEC.
 
Last edited by a moderator:


S

Silverburn

Member
It's not the output voltage that changes - it's fixed at 12V. It's the output *amps* that change.

I run 6S into it, so the output *amps* is 2A - a 4S setup will output 3A. No, I never worked out why bigger volts = less amps, but i'm sure someone who didn't fall asleep in high school physics will be along in a minute to explain :)

I didn't go for these ferrites for 2 reasons: a) they're $5 and expensive for what they are. b) I already had a ton of rin ferrites lying around. But by all mean, knock yourself out!
 

CrashMaster

CrashMaster

Member
Silverburn said:
PS - Tarrot say it needs a 3S, but then state 7.2-9V? That's not 3S...that's more like 2S. If Tarrot are using the Martinez controller board, then 3S/11.1V is best, which is why I recommend a single 12V BEC.
Click to expand...
The Martinez board can be set up to run on any voltage you want my altering the settings. However, the reason for the voltage guidance by Tarrot may be more to do with the brushless motors. The higher the voltage the faster they will move and compensate so by limiting the voltage to a range of 7.2-9v means they have set the Martinez to deal with that voltage to the motors and compensate for balance at a pre-determined speed so not over compensating and building up oscillation or bouncing.

Read page 10 on the linked PDF:- http://bradatech.com/xPedRobo/shop/download/uploading_software_martinez_board.pdf

I have one Martinez board running on 7.4v and a second on 11.1v both are identical but have differing settings.

I also have a HoverFly servo gimbal board running on 7.4v but their official documentation states 5v or 6v - what they really mean is 5v or 6v to 12v because the board can handle upto 24v from it's components but affects servo speeds and can damage both your flight RX, if connected and the servos if too high. This has nothing to do with the board it has to do with the servo and receiver power output. Again deceptive advice in the documentation.
 

kloner

kloner

Aerial DP
We typically use a product called "buck regulator" on rc aircraft for there cleaner rf and being compatible to 35 volts and can be tuned to any voltage you want. i use em on gimbals to create a constant voltage to the bgc, we use them for all the fpv stuff. Need to get some 1" heat shrink and a few of these.

http://www.amazon.com/RioRand-LM2596-Converter-Module-1-23V-30V/dp/B008BHAOQO

word of warning, do not plug these in reverse polarity, that little metal capacitor blows up and shoots off like a bullet. They work super good though, bullet proof. All the fpv community uses them or tbs core.
 

PeteDee

PeteDee

Mr take no prisoners!
If you do a search on ebay for buck regulators there is a few sellers with packs of five or ten including postage that work out at under $2 each, at that price it is worth have a few spares or spares to give to someone that needs an odd voltage BEC.

Pete
 


N

NYDave

Member
Thanks all, some great advice here. I appreciate everyone taking the time to add their input.

With the buck regulator suggestion, is it best to run two of these? One for the FPV transmitter and one for the gimbal? How easy is it to alter the output voltage? Am I right in thinking I won't need an additional filter or ferrites inline to keep interference at bay to get as clean a signal as possible on the FPV receiver? (I'm sure there are mixed views on the ferrites but it would be nice to not to have to carry a filter if we can help it).
 

CrashMaster

CrashMaster

Member
NYDave said:
Thanks all, some great advice here. I appreciate everyone taking the time to add their input.

With the buck regulator suggestion, is it best to run two of these? One for the FPV transmitter and one for the gimbal? How easy is it to alter the output voltage? Am I right in thinking I won't need an additional filter or ferrites inline to keep interference at bay to get as clean a signal as possible on the FPV receiver? (I'm sure there are mixed views on the ferrites but it would be nice to not to have to carry a filter if we can help it).
Click to expand...
Having read up on the manuals for both the Tarrot and the GAUI the voltages are different.

Like me you will have to run 2 UBECs:-
1. Tarrot will need a 7.2v or 9v unit http://www.hobbyking.com/hobbyking/store/__18786__9V_4_5A_UBEC_2_5S_Lipoly_6_23v_.html or http://www.hobbyking.com/hobbyking/..._5A_UBEC_2_5S_Lipoly_6_23v_UK_warehouse_.html
2. GAUI will need an 12v unit - http://www.hobbyking.com/hobbyking/store/__18787__12V_2_5A_UBEC_2_5S_Lipoly_12_23v_.html

That way you will have no issues with incorrect power supply. These units are only a few grams and include ferrites already so should have no issue at all with interference. I have almost the same setup but have 5V for camera and 7.2v for gimbal and the 5.8mhz AV TX is powered from the DJI PMU which is a UBEC but gives out 12v which my TX requires.
 

N

NYDave

Member
Mission accomplished... I went with the Buck regulator suggestion and bought two of these: http://www.amazon.com/RioRand-LM2596-Converter-Module-1-23V-30V/dp/B008BHAOQO

I connected each one up to one of my 4S batteries, tuned the output voltage by turning the brass screw on the top of each regulator and setup one for the Gimbal and one for the FPV transmitter. I wrapped them up in some heat-shrink, found a suitable spot to mount them on the frame and soldered them to the distribution board. My FPV tran. and tarrot gimbal are now both supplied by the main 4S battery. Test flights over the weekend went without a hitch. Job done.

Thanks again for the help and input. Greatly appreciated.
 


hershey

hershey

Someday Finally Got Here
I use a 4 cell lipo for my F450 quad. I use a FPV and GoPro camera for filming and fpv. The fpv is powered by a 3 cell so I just made a connector that connects only three cells of the lipo for it off of the balance lead. Works perfectly.
 

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