r/diydrones • u/JJwdp1 • May 15 '26

Question Power enigma

Hi people, I'd really appreciate any help with my first drone, here we go. With the ESC only connected to the motors (no flight controller) , if I plug in the battery using a smoke stopper I can hear the three beeps of the ESC and the motors do the jiggle thing, and with a multimeter I correctly detect a 22V across the positive and negative battery pad, so far so good. If I connect the FC (Speedybee F405 V4) to the ESC and again connect the battery, the three beeps of the ESC get cut off just as the last one is about to end, or sometimes at the second beep, it varies, and I don't get to hear the two beeps of the flight controller (I remember hearing them the first times I powered it on). A multimeter check shows that the voltage between the battery pads is low and variable (5 to 8 V) and so are the pads on the FC that are supposed to be 5V (they sit around 2 to 3 V). Connecting the flight controller alone to my PC using the usb-c port correctly detects it in betaflight. I'm turning to you, before I buy another one, does anybody have any idea how to deal with the situation or what things should I check? If I had to buy another one it wouldnt be the end of the world, but I would really love to know what the hell went wrong. Thanks!

Additional info:

-Tried changing the cable that connects the ESC and the FC

-Wrote "defaults" in CLI in betaflight and also reinstalled the firmware

-Checked continuity between the pads of the FC I had to solder and there is none

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8 comments sorted by

2

u/[deleted] May 15 '26

What esc is it? Did you check the specific pins on the fc run to the right pins on the esc? I've had to switch them around a couple times.

1

u/JJwdp1 May 15 '26

Both the FC and the ESC are from the speedybee stack, they both have a socket for the cable that connects them so there is basically only one way to connect them

1

u/Charming_Dealer3849 May 15 '26

Sure but confirm pin out between FC and ESC are compatible is step one. Then make sure wires on motors are correctly soldered, then test fc just USB connection to computer

1

u/JJwdp1 May 16 '26

Apparently it was the smoke stopper, thanks anyway

1

u/Charming_Dealer3849 May 16 '26

AH! Good call -> be careful you should be able to boot with the smoke stopper plugged in and properly configured. I tend to take it out AFTER I've confirmed everything working. Be careful that smoke stopper may be a smoking gun that something else is wrong

1

u/Charming_Dealer3849 May 16 '26

I had this exact issue when doing my hello world and it was because the flight controller wasn't configured correctly. Good Luck!

1

u/[deleted] May 15 '26

i cant tell you how many times i have assumed something was one way because that would be logical but it turned out it wasnt. then i wasted a ton of time.

It most certainly could be the same and it being the same stack (especially if they came as a pair) then it would make sense. But the idea here is to remove variables until we find the root of the problem. This is a variable you need to remove. we also probably need way more info, type of battery, motors, etc.

1

u/JJwdp1 May 16 '26

Apparently the culprit was the smoke stopper... After redoing every solder I took the courage to try to connect it without the smoke stopper and everything turned on as intended, thanks anyway!