Safe to connect external BEC to receiver without breaking FC or receiver?

esc

#1

I want to connect some strobon v2 navigation strobes to my receiver at some point, but when in strobe mode they draw 1A each, and I plan on having 2 of them on strobe mode and 2 on heartbeat mode, which draws 120mA per light. That makes 2.24A max that I need to support. My ESCs output 0.5A each, but I turned them into OPTOs by pulling the red wire out of the servo connector. If I put that wire back in, it wouldn’t help because the APMs input and output sides are disconnected from each other, and I definitely won’t put JP1 in to connect them because I’m using a power module. Because of this, I decided I would just hook up those strobe lights to my receiver with their servo connectors and connect an external BEC (5v @ 3A) to the receiver. But I’m worried that that will break either my receiver or my flight controller by feeding more current into both while my pixhawk power module is trying to do the same, not to mention that I’ll have to use an extra channel spot to plug the external BEC in. Can I do this or is there another way to give enough power to strobes (and/or servos if I use those)?


#2

Hi Robbie
I’ve just adding STROBON’s to my 250 Quad, red/green at rear on heartbeat and blue strobe at front.
Because the current drain on these varies as the LEDs glow up/down and peaks at about 1A when they flash I was determined NOT to power them from anything connected to flight controls.

I am using a tiny sBEC ( https://www.unmannedtechshop.co.uk/mini-bec-v2-voltage-regulator-3-3v-5v-12v/ ) solely to power the STROBONS and it works a treat.

Also because the 0V on this is the same as battery 0v you can link a RC channel to the S pad on the STROBONS for control / synchronising and it will not affect the power usage.
Hope this helps
Steve :slight_smile:


#3

Thanks, could you show me how it’s wired up?


#4

Hi Robbie @RobbieGM

I have a drawing for you, See link below

Cheers
Steve :slight_smile:

Strobon wiring.pdf (28.2 KB)


#5

@RobbieGM
@unmannedtech1

Note to Alex, you need to get more stock in of the 5v version :smiley: :smiley:
Cheers
Steve


#6

Thanks, stevietee, that drawing helps. What special kinds of servo connectors will I need to do that? I’ll probably be using 4 strobons not 3.

Thanks,
RobbieGM


#7

Haha yeah, constant struggle to keep stock levels good for some reason but got some more stock that arrived today! But am working on some news systems to predict stock more accurately.

https://www.unmannedtechshop.co.uk/mini-bec-v2-voltage-regulator-3-3v-5v-12v/


#8

@RobbieGM

The servo connectors are the usual that you plug into the RC receiver and probably the flight controller (depending on model)
as in photo below, you will only need two wires though, miss out the centre

The fourth Strobon just wires in parallel with the 3 shown.
If you have 4, all sync’d together then the quick pulse flashes, 4 at the same time, may momentarily overload a 2A sBEC. just try it and see if it is OK, no harm will come of it…
If you did not sync them then the randomly timed flashes would not be a problem

Cheers
Steve :slight_smile:


#9

I was planning on two of them staying solid or using heartbeat, something without a blink. What happens if you overload a BEC?


#10

Not a lot, the voltage just drops.
If sustained it may get a bit hot
I will power four up tomorrow, synced on strobe (worst case) and report back
Cheers
Steve :grinning:


#11

Yes, it all works OK
I’ve done a quick video, I’ll try to do a quick edit and post it later tonight.
Cheers Steve :slight_smile:


#12

@robbiegm

Hi
Apologies in advance for this ‘amateur’ video attempt, it’s just a quick video to support this forum thread. More apologies for the messy workbench, it’s usually cleaner, honest :laughing:
Enjoy
Steve :slight_smile:


#13

Thanks for the video, stevietee. Could I also use my (4) ESC BECs in parallel instead? They are connected to my APM 2.6 without JP1. I’m wondering if I could put a servo wire below the ESCs (as if plugging in a new ESC) and get power from there. Each ESC puts out 0.5a and I have four of them, so I should get 2 amps from that wire. Would that work instead of an external BEC, or would the four ESCs interfere with each other, or would it just not work at all?


#14

Are you able to check if your ESC have a linear or switching BEC. But in general it’s always best to only use one ESC to provide power as using multiple can cause issues, especially if they use switched BEC. However I would suggest you just use an external BEC/voltage regulator as then there is less chance for something to go wrong as you don’t exactly want an esc to fail mid flight because too much current is drawn from the bec on it.


#15

@RobbieGM
I agree with @unmannedtech1 and I recall I said the same in an earlier post, it is just not advisable to run these type of accessories of the infrastructure that keeps your craft up in the air
Is it really not worth a few quid to be safe?
Cheers Steve :grinning:


#16

My ESCs are Afro 30A ESCs with 0.5A linear BEC output. I found some 2A/3A 5V SBECs from HK that are really cheap and don’t require soldering. Should I use those (or any other external BEC really) or does it being a linear BEC make it ok to use four in parallel?


#17

I would buy the external BEC as it’s much safer and then cut rlthr red wire form all your esc so only the bec is powering everything.


#18

Ok, I’ll do that. I already have slid out the red wire from each ESC’s BEC connector, so now my APM 2.6 is getting power only from my pixhawk power module. The power module and the external BEC won’t interfere, right? I’ll probably plug the external BEC into the receiver like I would a servo, unless (is it?) that’s the wrong way to do it.


#19

@RobbieGM
The new sBEC input needs to come straight off the LiPo battery, before the Pixhawk power module.
This way it will not interfere with anything else on the craft and will not influence the current reading the power module gives to the APM FC.
I strongly suggest you follow the circuit in post 4/18
Cheers
Steve :slight_smile: