Motor overvoltage and PSU sizing

Hi, I’m new to brushless motors and the ODrive system. I need to use several ODrive D5065 Motors in my new project and I want to use an AC/DC PSU. I need their full torque, so after doing some quick calculations, it seems like I need to cope with quite a substantial load of power. I saw a recommendation to those Astec server power supplies ( in a different post. But judging from the label, it can only output at 42 volts. So here is my probably quite stupid question: Can I drive the 32-volt motors with this PSU, by liming current and speed with the ODrive? Or is there a different solution with, for instance, DC-DC converters?

Thanks in advance :slight_smile:

Yes, you can limit the top speed and use a larger voltage without issue.

Thank you very much, for your quick answer! I now decided to go with two 12V Power Supplies in series though.
I received my Odrive and I chose the one with the pre-soldered connectors. Compared to the wire gauges I need, to support the current, they seem pretty small. Are they capable of supporting a constant 100 amps over a long period? Or is there another recommended connector, that fits those bigger holes?

Thanks in advance and kind regards :slight_smile:

No, but neither is the ODrive unless you cool it a lot. If you plan on running the ODrive really hard, I would suggest you solder some thick wires directly to the bigger holes. You can use the bottom side of the board, and then you don’t need to desolder the screw terminals.
You can use a short wire with a large bullet connector so you can easily unplug things still.

Thanks a lot, for your quick support! I am actually planning on running two motors at 50 amps each. So the only connector, that is exposed to 100 amps is the power input one. I just read the post, showing max currents for the corresponding cooling methods and according to that, a simple fan would be enough to keep the ODrive cool.

Just for clearence, I would like to quickly introduce you to my project: I am a young student from Switzerland and I am working on my high school graduation project. My plan is to build a 6DoF robot arm. For axis 2, 3, 4 and 5 I want to use BLDCs with attached planetary gearboxes. Axis 2 and 3 are ODrive D5065 motors and axis 4 and 5 would be 4250-350kv motors. These are attached to Nema 23 and Nema 17 planetary gearboxes. There is actually a YouTube channel, that shows some amazing designs for BLDC and planetary gearbox robot actuators. (It’s called: “Skyentific”)
Once I finished building some working test joints, I’ll definitely post some pictures, etc. in a project topic.

Awesome yeah please post pictures and even work in progress if you want to!

Sure, I’ll see what my time schedule allows. :slight_smile:

You have to remember that you only get 16A from single phase. So 2600W. That Aztec gives you 2900 so you won’t need a 100 Amp connector unless you plan to run 3 phase power supplies.

It’s not because you send 100A total to the motors that the power input will be 100A


Carelsbergh Stijn

I switched to HP 1200W PSUs. Two in series for 24V and one for 12V. Every one of those will get it’s own 16 Amp 220V phase.

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Yes, it’s 50 Amps per motor, so the only connector exposed to 100 Amps is the input one. But I’ll solder the wire directly to the PCB anyways.


Amps don’t work like this with bldc motors but ok, if you solder it, it will be okay.



I plan on doing the same.
Did you have any issues?
Did you isolate PE or DC ground?
Do you control them with simple en signal or PMbus?
Do you read the current over an analog pin?

If that confused you here, I can help with a link


no, I didn’t run into any issues so far. It works really well.
I had to isolate the DC ground, by replacing the case screws with nylon screws and adding some nylon washers as well.
I also designed a custom PCB, to connect the two PSUs together. It adds the components, to automatically start the PSUs and it has nice big holes to solder the wires to. I found the correct card edge connectors on DigiKey, so you can remove or replace the PSUs more easily. I can send you the gerber files if you like.
I am actually a little bit confused with your last two points, so it would be great if you could help me with a link. :slight_smile:


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There’s a guy on the internet that reverse engineered them and posted it on his blog
They have a present signal, a enable, probably PMbus (Power management similar to I2C), and an analog pin with a voltage proportional to the current.

Do not disconnect PE. Isolate the DC ground from the shell of the psu. Place diodes across the psu output terminals.

And you’ll get 3680 watts from single 16A phase so a single phase is enough for you. With those 3 psu’s.

For connectors you should use something rated around 70A for the motors and about 100A for the input. Spec for more than you need.

I don’t use any monitoring for the output current. Here is a link, to my PCB project, there you can see, how I manage to start the PSU.

For motor connectors btw. I use bullet connectors and xt90 for the input.
These supplies also have sec.12V for eg. an arduino

I did not disconnect PE, I disconnected the DC ground, by isolating it from the PE connected case. I read about the diodes, I will add them in the next version of my PCB.

I also need to run two more stepper motors, a Jetson Nano running ROS and a seperate PC for programming. That won’t work with the remaining 80 watts. Therefore I deciced to run a 3 phase power cord, just to be on the safe side.

I will probably solder the wires directly to the ODrive. But for convenience I use 8mm bullet connectors, to be able to unplug it.

Thanks though!

Be careful, XT90s are only rated for 90 Amps. If you’re planing on using the whole 100 Amps, from the PSU, you’ll need to use bullet connectors as well. I recommend 8mm ones.

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