Hello everyone,
Apologies in advance—this is my first time building a drone, and it’s for a university project. I’m mainly a computer science student with only basic knowledge of electronics, so I’m not entirely confident my wiring diagram is correct. I’m also running into trouble connecting all my parts together.
I’m building an underwater drone for 3D modeling underwater structures, loosely based on the BlueROV design (sorry Blue Robotics, can’t afford one 
). I’m using some BlueROV parts, like their housing (15.6 aluminum locking tube) and cable glands. There is only one housing for everything, including the batteries. For power, I’m working with a Zeee 10,000 mAh 4S LiPo (not the exact one shown in the diagram).
I calculated the estimated power draw to be around 100 amps, and now I’m worried that the 8 AWG battery wire won’t handle it safely. Here’s my rough estimate:
- 13A per motor × 6 = 78A
- 5A per Raspberry Pi × 2 = 10A
- Unknown servo current
- Lights = maybe 3–4A, though I left headroom up to 10A
So potentially around 93–98 amps total. The motor ESCs are 50 amp if that helps as well. Can someone confirm if I’m on the right track here?
My assumption is that I’d need thicker wire, maybe 4 AWG or even 2 AWG, but I’m not sure. The wiring diagram I shared is more of a garage test setup so I had something to build off of. I’m now unsure what power module to use, especially since 100A seems to rule out most standard ones.
Also, I’m using a Pixhawk clone (couldn’t get the original), and I’m not sure if that affects which power module or power distribution board (PDB) I should go with.
If anyone has advice or suggestions, I’d really appreciate it. Sorry again if this all sounds very amateur and sloppy, I’m trying to figure this all out as I go without shocking myself or setting fire to my garage haha
Hi @Arcusmaster1
Welcome to the forums!
Your diagram looks sound, but all those fuses are likely unecessary and using up a lot of space and $$! You’ll notice that the BlueROV2 does not fuse the ESCs or power supplies… in general, surge currents can be quite high and make the fuses trip as a nuisance!
Many users have hoped to save money by building their own vehicle - generally you may find the economies of scale leveraged by BlueRobotics does make that the cheaper option, in the long run, but this will depend on your own fabrication costs.
As for your current estimates - you’re seemingly calculating a worst case load! A Raspberry Pi is not capable of drawing 5 amps - at most it draws 5-8 watts, when under load. The motors may be able to draw more than 13A, but when driving around at 50% gain, are unlikely to all be running at once. Forum posts in the past have discussed this… @EliotBR may be able to point you to these discussions as I couldn’t find them with a quick search.
As long as the pinout of your Pixhawk matches the pinout of the PDB, you should be able to connect and configure it to measure voltage and current appropriately! I hope you plan to run BlueOS on your pi with the connected autopilot…
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Hi Tony! Thank you for your insight! I’m still pretty new to electronics beyond gates and board-level components, so I figured adding fuses everywhere was a safe starting point. To be honest, I had to look up what gain was but I kinda get it now. Like you said, the fuse box definitely takes up way too much room lol. Wouldn’t a current surge damage small electronics and lights, though?
I am using BlueOS on the Raspberry Pi, and it’s talking to the Pixhawk fine. But I’m a little confused about power: should the 5V output from 2 BECs go to both the Pi and the Pixhawk, like it says on the ARDUsub wiring diagram, or just one for both? I noticed the Pi seems to power the Pixhawk via USB, which made me unsure about whether I need to power the Pixhawk separately.
I guess another example I have right now is I bought a servo for tilting one of the cameras. Do the positive and negative go in the Pixhawk or not? I have read online some instructions say to (but this was for drones/airplanes), and some people on forums say not to do that, and just attach the PWM signal line to it.
Also, do you think I should still look into a power distribution board? I was aiming for something that can handle 100A to be safe, but maybe that’s overkill if the actual sustained current is lower.
Lastly, I was a little concerned that the 8 AWG wire on my LiPo might not be enough for heavy load situations. But based on your estimates, do you think it’ll hold up without getting too warm?
Hi @Arcusmaster1 -
Your Raspberry Pi needs 5V, typically supplied via the header pins when using a Pixhawk. It also goes to the Pixhawk, even though the Pixhawk MCU is powered by USB, because it supplies the servo rail separately - this necessary if you want your tilt servo to have power !
The BlueROV2 uses screw terminals to link the ESC outputs to each of the motor wires. It then uses two large bus-bars, to gang positive and negative connections for all the ESCs and BEC together. You can purchase these from Blue Robotics!
Check the length of your 8 AWG wire with this calculator - I imagine it will be fine, unless you’re operating at full power all the time!
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@tony-white
Awesome, thank you for the tips! I actually just ordered the power supplies for the Pi and Pixhawk. it looks like the servo i wanted to use operates between 5 and 8.4 volts. I feel like this might be an issue, and it will need its own power if it has to go above 5V.
Hi @Arcusmaster1 -
If your servo works with 5V, the 5V BEC will power the Pixhawk rail and it will operate normally. If your servo requires higher voltage, you can supply it to the Pixhawk rail - as this voltage is only shared between output pins on the PWM output rail, and does not connect to the Pixhawk circuitry otherwise.
