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Power Distribution Boards
#1
Just thought I would write a little something about PDB's.

They come in all sizes and flavours, with each manufacturer claiming theirs is better than everyone else's.

So, do you actually need a PDB ?   Short answer is NO.

You do not NEED a PDB at all, you can simply use a wiring harness that connects all esc's to Lipo with perhaps 2 aux lines for extras. This method suits a lot of people .  Things to consider using this method.

1. If you run a 4S or higher system you need to be aware of your VTX and FPV cam input power requirements, not all support 16 volts directly.
2. If you are using OPTO esc's you will need to supply your own 5Volt bec
3. If using LED's you will also need a 12 volt bec or make sure your LED's can handle more than 12 volts
4. Add in a line filter for FPV gear  ***** Some people say they do not or never have required a LC filter*****, most of us actually do need one.


Should you consider using a PDB ?  Short answer is YES

Having a good PDB can make all the difference .

Think of it this way, You spend hours looking at different frames, reading reviews, user comments, spend hours researching the best bang for buck esc's and Motors, fpv cam and vtx's, but often overlook the humble PDB, either that or you accept the "free" pdb that comes with your frame.

Now, I am generalizing here, but a lot of the quad frames you buy that give you a free pdb are generally a bare bones basic PDB, sure it will do the job but will it actually meet your own personal build requirements ?

A bare bones PDB is just a board with - and + pads on it




These type of boards will do the job, with no fuss, but will still require you to purchase more parts.

Average cost for these, anywhere from $3 to $5 USD




The next type of PDB is the Basic with Pololu provision, these will set you back around $6 to $8 USD, but also factor in the price of a pololu of again around $6 to $8 USD,  Total cost around $16 to get a board with a 12 volt stepdown.




Again, this type will do the job fine, just remember to add in the cost of a 5 volt or 12 volt Stepdown





The next type is starting to get to where we want to be, approx cost $6 USD



This board has 12 volts for cam and VTX plus an extra Aux for led's, the aux port will supply power at the same voltage as the incoming supply.  Also, has no 5 volt for FC .





Now this is the type many of us want. Prices range for this type (not Brand) of pdb, prices from $35 USD to $50 USD




This type of PDB has dedicated power and line filtering for your VTX and FPV cam, filtered 12 volt and 5 volt rails.




Now, things to consider.

For all the PDBS that do NOT have 12 volt, 5 volt rails and filtered vtx and cam rails you have to factor in  Becs, Line filters, and then find space to fit the extras on your quad.


This is by no means a complete list of PDB types, I was just trying to simplify it down to 4 types from basic to full.


Personally I  think the PDB is one of the most important components on your quad, after all, it distributes the power to every part on your beloved quad, hex etc.

My advice is to research and be prepared to spend the cash on a good PDB.

A lot of faults can be traced back to a crappy PDB


Hope this has been a help to some.
#2
+1 Reputation! Very well written write up and descriptive. Thanks for taking the time to contribute!
I am a developing Racer - getting better.....
BNF Quads: <250 Eachine>; <250 Walkera Advanced CC3D>; <250 Vortex Pro>
Built: Dronz Fury 252 RX ; Speed Addict 210-R
Building: <Deciding on Third build - Suggestions?>
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#3
(03-17-2016, 05:50 AM)Hebrews12v2 Wrote: +1 Reputation! Very well written write up and descriptive. Thanks for taking the time to contribute!

Thanks Hebrews12v2, Just trying to share and help others.
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#4
Thank you for an excellent breakdown of power distribution! I have been worrying about an issue and bet you could help. So I'm building my first scratch build. Since I have a suitcase full of 3s batteries I want this one to be able to run 3s and 4s. Awhile ago I bought a Matek pdb, and that's when I learned about the issue with voltage sag causing vtx brown outs. Now I'm not sure the best way to wire this up.

My components will be:
12v camera
3s-6s vtx that outputs vcc and 5v
Opto esc's

Since I want to also use 3s lipos, should I stay away from any buck regulator? My best guess to prevent brown outs is to only use the 5v out of the pdb to power: fc->osd and rx. And run lipo voltage to vtx, then use the 5v out of vtx to a 12v boost pololu to power camera. Does that make sense?

Basically I'm wondering if its advisable to stay away from the 12v bec of pdb's if running a 3s/4s rig. I have a diatone v7 I can use. Perhaps the brown out issues are not common? What typically happens if you use the 12v bec on a 3s rig when voltage drops below 12v?

Thanks!
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#5
(03-18-2016, 01:51 AM)Bandook Wrote: Thank you for an excellent breakdown of power distribution! I have been worrying about an issue and bet you could help. So I'm building my first scratch build. Since I have a suitcase full of 3s batteries I want this one to be able to run 3s and 4s. Awhile ago I bought a Matek pdb, and that's when I learned about the issue with voltage sag causing vtx brown outs. Now I'm not sure the best way to wire this up.  

My components will be:
12v camera
3s-6s vtx that outputs vcc and 5v
Opto esc's

Since I want to also use 3s lipos, should I stay away from any buck regulator? My best guess to prevent brown outs is to only use the 5v out of the pdb to power: fc->osd and rx. And run lipo voltage to vtx, then use the 5v out of vtx to a 12v boost pololu to power camera. Does that make sense?

Basically I'm wondering if its advisable to stay away from the 12v bec of pdb's if running a 3s/4s rig. I have a diatone v7 I can use. Perhaps the brown out issues are not common? What typically happens if you use the 12v bec on a 3s rig when voltage drops below 12v?

Thanks!

Forget about the 3S vs 4S thing.

Build your Quad to 4S specs.

The correct type of PDB will solve all your problems.  Buy a full intergrated PDB that has filtered 12 volt and 5 volt rails, plus the LC filtered VTX and FPV cam pinouts (these can be set to either 5volts or 12 volts or Cam to 5 volts vtx to 12 volts or vice versa.)

So, if the quad is all setup for 4S then should you want to run a 3S lipo you do not have to do anything.

Hoping that makes sense.
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#6
Great article Smile thanks for sharing Steve!
Don't be a LOS'er, be a FPV'er :) -- My Fleet
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#7
(03-18-2016, 02:08 AM)BigglesFPV Wrote: Forget about the 3S vs 4S thing.

Build your Quad to 4S specs.

The correct type of PDB will solve all your problems.  Buy a full intergrated PDB that has filtered 12 volt and 5 volt rails, plus the LC filtered VTX and FPV cam pinouts (these can be set to either 5volts or 12 volts or Cam to 5 volts vtx to 12 volts or vice versa.)

So, if the quad is all setup for 4S then should you want to run a 3S lipo you do not have to do anything.

Hoping that makes sense.
OK, I figured I was over thinking things, thanks!  This is the Diatone board I have. Would this be OK? If not, can you recommend a solid board? I don't think the Diatone board has an LC filter, but I have made one in case I need it.
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#8
(03-18-2016, 03:03 AM)Bandook Wrote: OK, I figured I was over thinking things, thanks!  This is the Diatone board I have. Would this be OK? If not, can you recommend a solid board? I don't think the Diatone board has an LC filter, but I have made one in case I need it.

That Diatone board appears to have a LC filter, but the things I would look out for on PDBs as well is how many amps the board can take.

Just as a rough guide only (And someone with a electrical background may chime in here), if each Motor is capable of drawing lets say 15-20amps then the PDB needs to be able to handle that demand, otherwise bad things happen to the PDB.

Not saying that particular board will be bad, just be aware that cheap boards can also be cheap in quality and may be fine for 3S, put fail under 4S or higher.
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