Howdy all! PDBs?

[ShpHawK]

Glad to be here. Not sure if I'm supposed to post my question here, I'm new. Love the YouTube Channel. I have learned a lot. Clearly I still need to learn more. I have now fried my second Matek pdb-xt60. Not sure what I'm doing wrong. I checked them both prior to doing anything with a 4s battery and my volt meter. I soldered the xt60 connector and 5v pigtails on, and checked to see if all was well, and it was. I soldered the esc pigtail on, checked function and all was well. I plugged in the esc (Hobby Wing Sky Walker 60A Ubec), barely got the battery connected, and there was arcing and smoke. My ESC survived. The PDB, not so much. I cooked the insulation right off the wires in a split second. Is the ESC too much for the PDB? Can't imagine it draws a ton of current without the motor turning. Thanks for the help.

ShpHawK


P.s. Does anyone know of a good solution for connecting the power to my servos together to hook to the pdb? splicing them all together seems wrong. Also looking for the same for JST connectors.

Update: I got curious and took the volt meter to the pdb and everything actually checks out. Looks like I just smoked the wires. The question is still why. There doesn't appear to be any shorts.

 

[ElectriSean]

Can you post some pictures? You are correct that an unloaded ESC should pull very little current.

 

[dayve]

I don't have experience with that exact PDB. It looks fairly straightforward from the pics below. Are you sure the wires between the PDB and ESC aren't shorted? That's the most likely thing I can think of that would do what you described. Possibly there's a solder bridge between the + and - pads at either end of the wires between the PDB and ESC? Can you check that with a multimeter? I agree with ElectriSean. I'd like to see some pictures of your setup.

You've got me a bit confused when you say you want to connect several servos directly to the PDB. Typically the GND and 5V lines from the PDB would go to the receiver. The servos will plug in there. If you need 2 servos on one channel (often ailerons), a Y cable will do the trick.

I actually have joined multiple JST connectors together so I can charge 4 packs in parallel. Just twist them together, solder, and shrink wrap.

 

[ShpHawK]

Thanks for your help. Sorry it took so long. Had to take pics with my phone, email them to myself, and upload from my laptop. Thankfully the forums here aren't too picky about file or image size. I had already unsoldered the pigtail from the pcb, so I am holding it in place exactly as they were. I really thought so too about the short, but I can't identify where. The sparks and smoke appeared to come from the negative pad on the pdb. You can't really see the insulation in the photos, but it split all down the sides and full of carbon. In about half a second that wire got hot enough to BBQ dinner. I recently heard Bixler saying something about bad solder joints in a video, could that be it? I'm not detecting any shorts now. I've decided I don't trust it anymore, even though it checks out. I'm replacing it with a FCHUB-W. It has more BEC options. I just wish I knew what I did wrong. Why do they put the pads so close together?

As far as powering servos from the pdb, it was suggested that I do so as to not overwhelm the ESC's BEC. Might have been a flight controller video.

 

[ElectriSean]

In the third picture, it appears that the XT-60 is wired backwards.

 

[dayve]

I think ElectriSean probably nailed it.

Your ESC has a 3A BEC. Your PDB only has a 2A BEC. They're both switching BECs, so there isn't an efficiency to be gained by using one over the other. Personally, I'd wire it up like picture 4. The BEC in the ESC will power your receiver and any reasonable number of servos just fine. This makes your wiring much simpler since you won't have to mess with the power leads to your servos.

If you feel that you'll need more power for a VTX, lights, or other accessories, consider powering those from a separate BEC. You could use a PDB, but just connect the accessories to the PDB BEC. I'm using a HobbyWing UBEC in several planes, and have been very happy with it. It (or something similar) should be available for a few bucks wherever you shop. I buy them for $3 at Banggood.

 

[ShpHawK]

Yup. I did that. It was right in front of me. Thank you very much. To think I'm going to fly the thing once I finish building it.

Good point about running accessories from other BEC. Thanks again.

 

[cranialrectosis]

When you solder complicated stuff use a smokestopper.

 

[ShpHawK]

Awesome. I already have everything I need to build a smoke stopper. TY.