I've been jumping through some hoops to get things powered on my multi-rotor rigs lately and it occurred to me that a slightly more advanced version of the 3DR Power Module could solve it really neatly.
My suggestions for 2.0 is in addition to the power going to the APM and the pass-through power for the motors, have additional 5V and 12V breakouts. It would also be good if it could handle more than 4S, for larger Octocopter rigs:
Input: 12-25v (3S-6S)
Outputs:
1) bypass (same as input)
2) 5v for APM
3) 5v for other (camera gimbal servos, video tx, etc)
4) 12v (some common FPV gear, etc)
And I think the APM's power connector should use a more secure connection to the Power Module, I've had it come loose (thankfully not in flight) because that cable gets yanked around a bit connecting and disconnecting packs. Perhaps a Molex style connector with a little latch.
All in favor say 'aye!'
Replies
Design modification suggestions are worthy of exploration so must be encouraged and discussed wisely. The following are my thoughts.
KIS is a good approach on multirotors that are already very complex and don't glide well. An electrical glitch in any one "not critical for flight" device could in theory take the entire multirotor down. A reliability analysis will show that powering non-critical for flight components with a separate power suppply will increase safety and reliability. The RTL feature is a great capability that eliminates the need for FPV cameras, gimbals and etc. all of which are not essential for flight. So put them on a separate power supply. Don't stack more complexity onto the 3DR power module to accomodate non essential for flight gear.
Also you will find that a LiPo with the correct number of cells will directly power non-essential devices without voltage regulators thus saving weight, increasing endurance all while eliminating another source for failure.
Regarding the connector, the XT60 is well designed, cheap, and available. I can highly recommend this connector without any latching mechanism. In fact I find it somewhat difficult to pull aprart.
The many ways us users can screw things up increases exponentially with only slight increases in complexity. KIS!!!!
Ok so far what we have is a board that will have following features:
- Current/Voltage measurement
- 5V/1Amp regulator for APM/FlightController use
- Adjustable 5-7V/3Amp regulator for driving servos
- Passthrough for raw battery voltage
- Filtered output for FPV gear
I am still thinking if I should have output signals go trough this board or not. Having them going trough this board would be easier for newbies to connect their servos as I am a bit afraid that if we bring 6-7V to APM output rail.. Some will blow their APM because forget that jumper on it.
High power regulator might be on separate PCB for future changes etc but let's see
Any comments?
I am in the middle of a custom APM2.5 build and have really wanted to use the PM module in my build. One thing has been holding me back.
I have read many things online that suggest against the use of the PM module with anything over 3s batteries. As I understand it the problem is that even though the PM module has a stated input voltage maximum of 18v, using a 4s battery at 16.8v can introduce ESD spikes that will go well beyond the 18v recommended maximum. It seems to me that the 18v recommended maximum should take into account the possibility of ESD spikes, and that the PM module 'should' have some sort of ESD suppression built into the circuitry. I have yet to read anything either on the datasheets for the components listed in the EagleCAD files, or in any forum discussion surrounding the PM module that states that an ESD suppression system was implemented in it's design.
For that reason alone I would spring for a 'beefier' version of the PM module in a heartbeat. I have been studying many datasheets and electrical engineering articles trying to figure out a way of modifying the current PM module so that I could use it safely with a 4s pack without having any worry that I could fry my APM with an ESD. As I am new to the electrical engineering field I have not had much success, but I am willing to put forth the money to have the pcb prototypes made and assembled if someone has a clear idea of how this could be achieved.
In this respect, I also would like to see a picture of your rig Thomas and I will be searching for eagle files on the AnyVolt regs you speak of to see if their circuitry could be adapted easily. If it comes to it I will purchase an AnyVolt regulator to do the comparison work myself. Do you, or anyone else, have a suggested vendor for them in the US?
-Bill
I bought one of those pdm's. I thought it was junk. So I made my own, like this.
You'll need:
Deans ultra wire
Batt connectors, motor connectors
Automotive ring clips
2) 1/4 by 3/8 or 1/2 Stainless steel bolts and nuts.
Neoprene foam
Cut the amount of wires you need to length and put the ring clips on one end.
I added two pair extra as power take offs. They connect to separate adjustable voltage regulators, one a Castle for the APM
and it's related outputs, and the other runs into a small bank of AnyVolt regs, which gives me 3 more sources of power for, lights, cameras, video transmitters.
Bolt it all up and put the foam around it with cable ties.
You'll have two "spider hubs" capable of very high voltage and current handling.
Tip: Keep all the motor wires exactly the same length for resistance matching and time alignment.
Works awesome for my heavy lift machines.
T
I vote aye!
As an added suggestion for the future, how about building the Power Module into the Power Distribution Board. I think that would be super slick, one less added on component. Has anyone considered that? I cut the connector off my PM and soldered it directly to the PDB to at least get rid of the extra connection.
maybe this , instead of PTH08080 on 3DR Power Module
4.5V to 28V Input, Dual 3A Outputs
I have been working awhile with similar idea so let's start to look this more. I was also looking to have one power unit that will have 2 inputs for redundant 5V supply.
Personally I was going to mod mine to be soldered using the pads on the back, and use servo connectors. Servo connectors seen more robust than the DF13 style cable for power applications. Though all connectors are potential problems.
-
1
-
2
of 2 Next